THE PRODUCTION, DISPOSAL, AND BENEFICIAL USE OF COAL
COMBUSTION PRODUCTS IN FLORIDA
By
CALLIE JANE WHITFIELD
A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF ENGINEERING
UNIVERSITY OF FLORIDA
2003
ACKNOWLEDGMENTS
I would like to first acknowledge and thank the Florida Department of
Environmental Protection for the grant funding that made this project possible. I am also
grateful to the Florida Electric Utility Coordinating Group and the member utilities that
participated in this research and provided data and technical assistance.
I acknowledge and thank Dr. Angela S. Lindner, my supervisory committee
chairperson, for her time, hard work, leadership, and guidance during this project. I
thank my committee members Drs. Joseph Delfino and Chang-Yu Wu for their direction,
time, and support. I am also very grateful to my research group for feedback and support
throughout this project. I acknowledge and thank Greg Babbitt and my family for
editorial and moral support.
I also acknowledge and thank the American Coal Ash Association, the Electric
Power Research Institute, and the coal combustion product marketers participating in this
research, who all provided valuable technical resources for this project. I also recognize
the Florida Center for Solid and Hazardous Waste for coordinating the grant
administration.
ii
TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS .................................................................................................. ii
LIST OF TABLES............................................................................................................. vi
LIST OF FIGURES ......................................................................................................... viii
ABSTRACT.........................................................................................................................x
CHAPTER
1
INTRODUCTION ........................................................................................................1
A Case for the Beneficial Use of Coal Combustion Products ......................................2
Research Scope.............................................................................................................3
2
REVIEW OF LITERATURE .......................................................................................5
Status of Electricity Generation and Consumption ......................................................5
Electricity Generation and Coal Combustion Product Origin ......................................6
Coal Combustion Product Generation ..........................................................................9
Fly Ash Production..............................................................................................12
Bottom Ash and Boiler Slag Production .............................................................14
Flue Gas Desulfurization Material Production....................................................14
Characterization of Coal Combustion Products .........................................................17
Fly Ash ................................................................................................................17
Bottom Ash and Boiler Slag................................................................................19
Flue Gas Desulfurization Material ......................................................................20
Coal Combustion Product Generation Trends and Forecasts .....................................22
Coal Combustion Product Disposal............................................................................25
Coal Combustion Product Beneficial Use Opportunities ...........................................28
Concrete Products................................................................................................29
Aggregates...........................................................................................................32
Autoclaved Cellular Concrete .............................................................................33
Road Base and Subbase.......................................................................................33
Concrete and Asphaltic Concrete Pavements......................................................34
Structural Fill and Embankments ........................................................................35
Flowable Fill........................................................................................................36
Manufactured Products........................................................................................37
Roofing granules and blasting grit ...............................................................37
iii
Wallboard .....................................................................................................38
Cenospheres and filler in paint, plastics, and other products .......................39
Agricultural and Environmental Applications.....................................................40
Soil amendment............................................................................................40
Acid mine drainage and surface mine reclamation ......................................41
Daily landfill cover.......................................................................................42
Waste stabilization .......................................................................................42
Metals recovery ............................................................................................43
Legislative History of Coal Combustion Products .....................................................44
Federal Regulatory History of Coal Combustion Products.................................45
Future Regulatory Issues .....................................................................................50
State Regulations on Fossil Fuel Combustion Products......................................51
CCP Regulatory Issues in the State of Florida ....................................................53
3
LIFE CYCLE ASSESSMENT OF COAL COMBUSTION PRODUCTS ................55
Introduction.................................................................................................................55
Method........................................................................................................................57
Scope and Goal Definition ..................................................................................58
Functional unit..............................................................................................59
System description and boundaries ..............................................................60
Inventory Analysis...............................................................................................66
Data collection..............................................................................................66
Data quality ..................................................................................................67
Data limitations ............................................................................................68
Allocation .....................................................................................................68
Impact Assessment ..............................................................................................69
Results and Discussion ...............................................................................................72
LCA Scope ..........................................................................................................72
Inventory Results.................................................................................................72
Impact Assessment Results .................................................................................76
Impact characterization ................................................................................77
Normalization and damage assessment........................................................80
Interpretation .......................................................................................................83
Sensitivity analysis.......................................................................................83
Comparison of CCP management scenarios ................................................90
Conclusions.................................................................................................................94
4
RECOMMENDED BEST MANAGEMENT PRACTICES FOR COAL
COMBUSTION PRODUCTS AT FLORIDA UTILITIES .......................................96
Introduction.................................................................................................................96
Methods ......................................................................................................................97
Data Collection....................................................................................................97
Characterization of CCP Generation, Beneficial Use, and Disposal in Florida ..98
Creation of BMPs ................................................................................................98
Results and Discussion ...............................................................................................99
iv
Characterization of CCP Generation, Beneficial Use, and Disposal in Florida ..99
CCP Beneficial Use BMPs................................................................................101
Storage and handling..................................................................................101
Beneficiation ..............................................................................................103
Transportation to beneficial use market .....................................................107
Beneficial use .............................................................................................110
CCP Disposal BMPs..........................................................................................122
Storage and handling..................................................................................123
Treatment and fixation ...............................................................................123
Disposal by landfill and long-term storage ................................................124
Disposal or storage by surface impoundment ............................................125
General CCP Management Best Practices ........................................................126
Annual CCP generation reports..................................................................126
CCP beneficial use environmental guidelines............................................127
Conclusions...............................................................................................................127
5
SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS............................129
Summary...................................................................................................................129
Conclusions...............................................................................................................129
Recommendations.....................................................................................................131
APPENDIX
A
REGULATORY STATUS OF CCPS IN EACH STATE .......................................132
B
DATA COLLECTION SURVEYS AND QUESTIONNAIRES ............................136
Site Visit Questionnaire............................................................................................137
Utility Follow-up Survey..........................................................................................141
CCP Marketers Survey .............................................................................................145
C
COLLECTED DATA ..............................................................................................148
D
LIFE CYCLE ASSESMENT INVENTORY RESULTS ........................................161
LIST OF REFERENCES.................................................................................................167
BIOGRAPHICAL SKETCH ...........................................................................................176
v
LIST OF TABLES
Table
page
2-1: Classification of coals by rank and group ....................................................................7
2-2: Chemical and physical properties of large-volume CCPs..........................................22
2-3: Beneficial use markets for CCPs in general and specific to Florida ..........................44
3-1: Average ultimate analysis of coal on an as-received basis at Florida utilities ...........63
3-2: Beneficial uses considered for each large-volume CCP.............................................65
3-3: Process block data obtained from SimaPro databases................................................67
3-4: Impact categories and units for each impact assessment method used ......................70
3-5: Summary of four Florida utilities used for LCA system modeling............................72
3-6: Inventory of raw material inputs for each life cycle stage .........................................73
3-7: Inventory of emissions to air from each life cycle stage ............................................74
3-8: Inventory of emissions to water from each life cycle stage .......................................75
3-9: Inventory of emissions to soil from each life cycle stage ..........................................76
3-10: Input variations used to perform sensitivity analysis ...............................................84
3-11: Sensitivity analysis results for coal mining and preparation ....................................85
3-12: Sensitivity analysis results for coal combustion.......................................................86
3-13: Sensitivity analysis results for CCP beneficial use ..................................................87
3-14: Sensitivity analysis results for CCP disposal ...........................................................88
4-1: Characterization of CCPs generation, use, and disposal in Florida. ..........................99
4-2: Scenarios for comparing transportation requirements and beneficial use................107
A-1: Matrix of state regulations on CCP disposal and beneficial use .............................132
vi
B-1: Utility follow-up survey table of CCP markets .......................................................144
B-2: Utility follow-up survey table of factors affecting CCP beneficial use...................145
B-3: CCP marketer survey table of amounts and market prices for CCPs ......................145
B-4: CCP marketer survey table on CCP beneficial uses ................................................146
C-1: Data collected on coal mining and preparation .......................................................148
C-2: Data collected on coal combustion ..........................................................................150
C-3: Data collected on CCP Beneficial Use ....................................................................152
C-4: Data collected on CCP Disposal..............................................................................154
C-5: Toxic Release Inventory (TRI) data collected for each utility ................................156
C-6: TRI emissions from disposal facilities at each utility..............................................160
D-1: Inventory results for raw materials used..................................................................161
D-2: Inventory results for emissions to air ......................................................................162
D-3: Inventory results for emissions to water..................................................................164
D-4: Inventory results for emissions to soil....................................................................166
vii
LIST OF FIGURES
Figure
page
2-1: Typical pulverized coal combustion system.................................................................9
2-2: Pulverized coal utility boiler schematic .....................................................................11
2-3: Fly ash production and beneficial use trends .............................................................23
2-4: Bottom ash production and beneficial use trends.......................................................23
2-5: Boiler slag production and beneficial use trends........................................................24
2-6: FGD Material production and beneficial use trends...................................................24
2-7: Trends in percentage of CCP used, by type of product..............................................25
3-1: Level 1 and 2 diagram for an LCA of CCPs ..............................................................60
3-2: Level 3 diagram for an LCA of CCPs ........................................................................61
3-3: Eco-indicator 99 impact characterization...................................................................77
3-4: CML impact characterization .....................................................................................78
3-5: EDIP impact characterization.....................................................................................79
3-6: Normalized human health impacts from each life cycle stage ...................................81
3-7: Normalized ecosystem quality impacts from each life cycle stage............................82
3-8: Normalized resource depletion impacts from each life cycle stage ...........................82
3-9: Relative change to damage categories due to sensitivity analyses.............................89
3-10: Comparison of CCP disposal and beneficial use......................................................91
3-11: Comparison of CCP disposal options.......................................................................92
3-12: Comparison CCP transportation scenarios...............................................................93
4-1: Comparison of dry and wet storage systems. ...........................................................102
viii
4-2: Comparison of FGD disposal and FGD gypsum use with beneficiation. ................104
4-3: Schematic of a triboelectric fly ash beneficiation system ........................................105
4-4: Comparison of fly ash disposal and fly ash use with beneficiation. ........................106
4-5: Environmental and economic comparison of beneficial use and transportation
scenarios. ..................................................................................................................109
4-6: Comparison of fly ash and Portland cement for concrete production. .....................111
4-7: Comparison of CCPs and sand and gravel for structural fill....................................113
4-8: Comparison of flowable fill made from fly ash and cement mixtures. ....................114
4-9: Comparison of soil amendment with CCPs and traditional materials......................116
4-10: Comparison of road construction with and without CCPs. ....................................118
4-11: Comparison of roofing granule and blasting grit production with and without boiler
slag. ........................................................................................................................119
4-12: Comparison of FGD and natural gypsum in wallboard..........................................120
4-13: Comparison of landfills with and without a liner...................................................124
4-14: Comparison of surface impoundments with and without a liner............................125
ix
Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Engineering
THE PRODUCTION, DISPOSAL, AND BENEFICIAL USE OF COAL
COMBUSTION PRODUCTS IN FLORIDA
By
Callie Jane Whitfield
August, 2003
Chair: Angela S. Lindner
Major Department: Environmental Engineering Sciences
Coal-fired electric utilities in the U.S. annually generate over 100 million tons of
large-volume coal combustion products (CCPs), including fly ash, bottom ash, boiler
slag, and flue gas desulfurization (FGD) material. Management of these products has
created a challenge for utilities and regulators. CCPs have chemical and physical
properties that make them suitable for beneficial use in engineering and construction
applications. However, these products also have chemical constituents, mainly trace
metals, that cause concern about their widespread beneficial use and their disposal at the
utility. With these issues in mind, the goal of this investigation was to characterize CCP
generation, beneficial use, and disposal at Florida utilities and to examine and compare
environmental impacts created during the life cycle of CCPs.
Characterization results indicated that CCP generation, beneficial use, and disposal
practices vary between utilities and are most strongly influenced by combustion operating
parameters and fuel source. In Florida, CCP generation varies between 160,000 and
x
1,185,000 tons per year, and beneficial use rates can range between 0 and 99 percent.
The most common CCP uses are cement and concrete production with fly and bottom
ash, FGD gypsum wallboard manufacture, and blasting grit and roofing granules made
from boiler slag. CCPs not beneficially used are disposed at the utility in landfills,
surface impoundments, or both.
A life cycle assessment (LCA) was then performed using SimaPro software by PRé
Consultants. The LCA determined comparative environmental impacts at each stage of
the CCP life cycle: coal mining and preparation, coal combustion, CCP beneficial use,
and CCP disposal. Based on the LCA results, CCP disposal presented the highest levels
of impacts to human health and ecosystem quality, while coal mining and preparation
represented the highest impact to resource use. CCP beneficial use was shown to have a
negligible contribution to the total life cycle impacts.
These results were used to compare different beneficial use and disposal scenarios
and create a set of recommended best management practices for CCPs at Florida utilities.
One hundred percent beneficial use of CCPs was shown to have over 100 percent less
human health and ecosystem quality impacts and 15 percent less resource impacts, as
compared to CCP disposal. Beneficial uses that showed the lowest environmental
impacts were cement and concrete production, gypsum wallboard, roofing granules,
blasting grit, structural and flowable fill, waste management, and materials recovery.
Considering CCP disposal on a life cycle basis, a landfill had almost 20 percent less
impact to human health but 5 percent higher impact to ecosystem quality and 95 percent
higher impact to resource use, as compared to a surface impoundment. In either case, use
of a liner was shown to decrease the total environmental impact by up to 50 percent.
xi
CHAPTER 1
INTRODUCTION
Almost 108 million metric tons of high-volume coal combustion products (CCPs),
including fly ash, bottom ash, boiler slag, and flue gas desulfurization material, are
generated on an annual basis within the United States (American Coal Ash Association
[ACAA], 2003). Additional waste generated in much lower volumes includes coal pile
runoff, coal mill rejects and pyrites, boiler blowdown, cooling tower blowdown and
sludge, water treatment sludge, regeneration waste streams, air heater washwater, boiler
chemical cleaning wastes, floor and yard drains and sumps, laboratory wastes, and
wastewater treatment sludge (United States Environmental Protection Agency [U.S.
EPA], 1999). The treatment, storage, disposal, and reuse of both types of waste, high and
low volume, present a management challenge for utilities nationwide.
Current estimates indicate that only about 34 million tons of high-volume
combustion products produced in the United States are reused in a beneficial application,
including cement and concrete production, road pavement, soil amendments, material
recovery, and waste stabilization, while the remaining 72% of these materials are
disposed of, generally in landfills or surface impoundments (ACAA, 2003). This fraction
of reuse is quite small compared to other regions. In Europe, 54% of all CCPs are
directly used in beneficial applications, while another 33% are diverted from disposal for
use in restoring mines and quarries (Gainer, 1996). Even more impressively, in Japan,
almost 75% of all CCPs are reused in advantageous applications, and, in Shanghai,
1
2
China, almost 100% of CCPs are recycled for beneficial use (Gainer, 1996; Swanekamp,
2002).
A Case for the Beneficial Use of Coal Combustion Products
The large quantity of CCPs disposed of in landfills and surface impoundments
annually in the U.S. creates additional strain on waste management options that are
already approaching their capacity for safe and sanitary operation. Although landfills are
designed and constructed to minimize human and environmental health impacts, there is
still a great deal of uncertainty surrounding CCP behavior in a landfill, including heavy
metal speciation and leachate impacts over extended periods of time. Additionally, as
landfills are increasingly used and their maximum capacity is approached, the economic
cost of combustion product disposal rises. Based on the potential human health risks,
environmental impacts, and economic costs associated with CCP disposal, the beneficial
use of these products becomes an increasingly attractive alternative. CCP beneficial use
minimizes or eliminates the cost and problems of disposal; requires less area for disposal,
enabling other land uses and decreasing permit requirements; achieves financial returns
from product sales; replaces some scarce or expensive natural resources; and conserves
energy required for processing or transporting the products for disposal (Joshi and Lohtia,
1997).
Based on these potential benefits, using CCPs in economically and environmentally
sound applications has become an increasingly and mutually attractive option for utilities
and CCP beneficial use industries alike. However, great uncertainty also surrounds the
long-term performance and environmental impacts of many CCP beneficial uses. Some
of these uncertainties include efficiency and durability of CCP products compared to
traditional materials, the potential for future regulation of CCPs as hazardous or special
3
wastes, the fate of trace metals and other compounds contained within the CCP, and the
potential for impact on human and environmental health over extended periods (Joshi and
Lohtia, 1997). An additional concern is the short- and long-term consistency of the
combustion products designated for specific beneficial uses. As there are numerous
power plants operating under varied conditions and using different types of coal and
other fuel sources, it is reasonable that the resulting combustion products have different
physical and chemical characteristics. Additionally, future regulatory or technology
changes can have significant impact on CCP quality and consistency. For example, air
emissions regulations could require reductions in NOx by technology (such as low-NOx
burners) that could potentially decrease the conversion of carbon in the coal. A high
level of unburned carbon in fly ash decreases its marketability as a cement replacement
for concrete production. Another example is in the future regulation of Hg emissions
from power plants, where a promising control strategy is injection of activated carbon or
other sorbents into the fly ash laden flue gas (Sjostrom et al., 2002). However, the
presence of carbon sorbents in fly ash is a detriment to its use in concrete production and
other beneficial uses.
Therefore, it is necessary to be able to characterize the physical and chemical
properties of these products, identify the fossil fuel conversion life-cycle parameters that
directly affect current and future CCP quality and use potential, and evaluate the
comparable environmental and human health impacts, if any, associated with beneficial
use or traditional waste management and disposal options.
Research Scope
The scope of this research includes the investigation of CCP generation, disposal,
and beneficial use specific to the State of Florida, as well as the formation of a
4
comparative baseline for national CCP disposal and beneficial use activity. The scope of
research is two-fold, first including a literature review to provide current knowledge in
coal combustion product characteristics, disposal and beneficial use trends, regulation of
CCPs, and potential environmental and human health exposure pathways and risks.
Secondly, the research includes data collected on CCP generator identification and
location, electricity generation operating parameters, CCP characteristics, and disposal
and beneficial use methods specific to the state of Florida. A life-cycle assessment
(LCA) is used to evaluate environmental impacts at each stage of CCP generation, link
the effects of coal characteristics and operating conditions on the beneficial use potential
of CCPs generated, and relate disposal and beneficial use methods to potential human and
environmental health impacts.
Completion of this work will allow a better understanding of the fate of coal
combustion wastes in Florida and will provide a useful means of guiding generators and
regulators towards more economical and environmentally friendly disposal and beneficial
use practices. Additionally, this research will add to the continuously growing body of
knowledge on pollution prevention and waste management and reuse.
CHAPTER 2
REVIEW OF LITERATURE
Status of Electricity Generation and Consumption
Over 3,700 billion kilowatt-hours of electricity are consumed in residential,
commercial, industrial, and transportation sectors of the United States annually, making
the generation, transmission, and distribution of electricity one of the largest industries in
the country (Energy Information Agency [EIA], 2002). The average national electricity
demand has increased by approximately 1.3% each year, although this average annual
growth in energy demand is projected to increase to 1.8% over the next 20 years, because
of population growth (EIA, 2002).
Electricity generation facilities operate primarily by the combustion of fossil fuel to
generate electric energy. On a national basis, coal-fired processes make up 60% of the
total net electric generation by utilities, with the remaining percentage comprised of 20%
nuclear power, 10% natural gas, 7% hydroelectricity, 3% oil, and 0.1% other energy
sources, including biomass and wind power (EIA, 2002). In Florida, 55 utilities operate,
with an average fuel mix of 39% coal, 22% oil, 21% natural gas, 16% nuclear, and 2%
renewables, although these percentages vary greatly on a site-by-site basis (Emissions
and Generation Resource Integrated Database [EGRID], 2001). Although coal-fired
plants have traditionally been the workhorses of the electricity generation industry
nationally and in Florida, they have lately become less attractive because of higher capital
costs, longer times required for construction, and lower overall efficiency, as compared to
other fuel-powered plants. Conventional coal-fired boilers operate with efficiency of 305
6
40 percent, while natural gas systems and combined cycle gas turbines operate with
efficiency up to 50-60 percent (Beér, 2000; Sondreal et al., 2001). In recent years,
natural gas combustion facilities have been gaining larger market shares, and it is
projected that a majority of newly constructed power plants will rely on natural gas as a
primary fuel source (EIA, 2002). However, given the low raw material cost and broad
availability of coal, this fuel source can be expected to remain an essential supply for
electricity production throughout the 21st century (Beér, 2000).
Electricity Generation and Coal Combustion Product Origin
Despite projected shifts to cleaner fuel sources, in the near future, electric utilities
will continue to rely heavily on fossil fuels, particularly coal, as primary energy sources.
From an environmental perspective, coal utilization presents a number of problems for
utilities, as coal combustion processes generate significant amounts of by-products at
each stage during electricity generation. For clarity and future reference, an overview of
stages in the combustion process for electricity production is detailed here. A schematic
representing the typical operation of a pulverized coal combustion systems is shown in
Figure 2-1.
Coal is extracted by underground and surface mining from coal seams located in
the Northern Rocky Mountains and Great Plains, Colorado Plateau, Western Interior,
Illinois Basin, Gulf Coast, and Appalachian Basin areas of the United States (United
States Geological Survey [USGS], 2001). Coal is classified in one of four ranks that
reflect the degree of metamorphism of the coal and typically correspond to the geologic
age of the coal deposit and to the heating value of the coal (U.S. EPA, 1999). These four
ranks of coal are anthracite, bituminous, subbituminous, and lignite. The most common
ranking system is ASTM D 388. In this system, coals that contain fixed carbon in
7
percentages greater than 69 percent by weight are classified by their fixed carbon alone,
irregardless of their colorific value (Babcock and Wilcox, 1978). Coals below this cutoff
percentage are classified by their calorific value. A summary of the classification of the
four coal ranks according to ASTM D 388 is presented in Table 2-1. Of these coals,
bituminous and subbituminous are most commonly used for electricity generation, while
anthracite is not generally used as a fuel source in utilities (Joshi and Lohtia, 1997).
Table 2-1: Classification of coals by rank and group
Fixed Carbon
Limits, (%)
(Dry, mineralmatter-free basis)
Class
I. Anthracite
II. Bituminous
III. Subbituminous
Group
Greater or
equal to
Less
than
Volatile Matter
Calorific Value
Limits, (%)
Limits (BTU/lb)
(Dry, mineral(Moist, mineralmatter-free basis) matter-free basis)
Greater
Less Greater or Less
or equal
than
equal to
than
to
1. Meta-anthracite
98
---
---
2
---
---
2. Anthracite
92
98
2
8
---
---
3. Semianthracite
86
92
8
14
---
---
1. Low volatile bituminous coal
78
86
14
22
---
---
2. Medium volatile bituminous coal
69
78
22
31
---
---
3. High volatile A bituminous coal
---
69
31
---
14,000
---
4. High volatile B bituminous coal
---
---
---
---
13,000
14,000
5. High volatile C bituminous coal
---
---
---
---
11,500
13,000
1. Subbituminous A coal
---
---
---
---
10,500
11,500
2. Subbituminous B coal
---
---
---
---
9,500
10,500
3. Subbituminous C coal
---
---
---
---
8,300
9,500
1. Lignite A
---
---
---
---
6,300
8,300
2. Lignite B
Adapted from ASTM D 388 by Babcock and Wilcox, 1978.
---
---
---
---
---
6,300
IV. Lignite
After it is extracted, coal is usually cleaned at or near the coal mine in order to
remove impurities, namely sulfur and ash, and to normalize the size distribution by
eliminating fines and very large pieces. Cleaning processes include washing, gravity
separation, sizing by crushing and screening, and drying (Babcock and Wilcox, 1978).
The clean, dry coal is transported from the mine or cleaning process to the utility using
freight train, barge, and truck, or a combination of some or all of these methods. Overall,
the U.S. average for these three modes of transportation breaks down to 73 percent by
8
freight train, 15 percent by barge, and 12 percent by truck (Chicorp, 1999). During its
transportation, the coal must usually be treated with water or an oil-based compound to
minimize fugitive dust emissions and coal loss in transit (Babcock and Wilcox, 1978).
Before combustion in a typical modern coal-burning power plant, coal is dried and
ground to a fine powder in a pulverizer, as shown in Figure 2-1, to narrow the size
distribution, so that 70% of the coal is less than 75µm in diameter (Dienhart et al., 1998).
Pulverization increases the surface area available for combustion and thus improves
combustion efficiency. The fineness to which the coal is pulverized depends on the coal
rank and the corresponding reactivity of the coal (Beér, 2000). The pulverized coal is
pneumatically transported and injected into the combustion chamber, where it is mixed
with preheated excess air and ignited at temperatures reaching 1400oC (Babcock and
Wilcox, 1978). Coal particles burn in a mode in which both external diffusion of oxygen
to the particle surface and chemisorption of the oxygen at the particle surface and in the
pores of the solid char determine combustion progress. Diffusion controls the burning
rate of large particles at high temperatures, and chemical kinetics controls the burning
rate of small particles as the char burns out in the tail end of the flame (Beér, 2000).
During the combustion process, the hot combustion exhaust gases, combustion
products, and radiant heat produce steam from water in heat exchangers (boiler tubes)
surrounding the boiler. The superheated steam passes rapidly through a turbine and
expands with a decreasing temperature gradient. The expanding steam causes the turbine
blades to rotate the turbine shaft and attached generator at extremely high velocities. The
wire coils in the generator produce electric energy as they are rotated in a strong
magnetic field. During this cycle, the steam is continuously condensed and returned to
9
the boiler for reuse. At this point, the flue gases are still at elevated temperatures,
between 700-1000oF, and would drastically decrease boiler efficiency if exhausted to the
atmosphere at these temperatures (Babcock and Wilcox, 1978). Therefore, the heat
content of these gases is recovered in one or both of two types of heat exchangers. One
such heat exchanger is the air heater, in which some or all of the low-grade heat in the
flue gas is used to preheat the air supplied for combustion. Another type of device,
known as an economizer, is used to raise the incoming temperature of the feed water used
for steam production in the boiler. Not only does this preheating improve efficiency with
which steam is generated, it also serves the purpose of cooling the combustion products
and exhaust gas to safer, easier to handle temperatures.
Wet
From CARRC, 2002.
Figure 2-1: Typical pulverized coal combustion system
Coal Combustion Product Generation
Although the combustion process is continually being optimized to increase the
efficiency by which fuel is combusted for electricity production, there are still large
amounts of process wastes and byproducts generated by electric utilities. These wastes
10
and byproducts are generally categorized as being large-volume or low-volume products,
based on their annual generation rates. This research focuses primarily on the four largevolume coal combustion products (CCPs), fly ash, bottom ash, boiler slag, and flue gas
desulfurization (FGD) material, although low-volume wastes are also examined on a
limited basis. The demarcation between quantities required for a waste to be classified as
large- or low- volume has not been completely established, except to indicate that fly ash,
bottom ash, boiler slag, and FGD material would be classified as large-volume products
due to their consistently high production rates, whereas all other products would be
termed low-volume wastes (U.S. EPA, 1999).
These large-volume CCPs originate primarily from the chemical compounds in a
coal source that cannot be combusted during electricity production, but that are carried
through the process by nature of the equipment and technology used. Coal is a complex
mixture of organic and inorganic phases, combined with large quantities of physically
and/or chemically bound water. The inorganic phase, which may amount to 15-20% of
the total coal weight, is a complex mixture of quartz, pyrite, calcite, and silicates
(Ledesma and Isaacs, 1990). Various metals are also present in trace amounts. During
combustion, the inorganic fraction of the coal is converted to ash, steam, and other noncombustible materials. Specifically, ash and slag are derived from the ash content of the
source coal, and FGD material is generated upon removal of the sulfur present in the
source coal.
The types of CCPs produced and their physical and chemical properties are
determined primarily by the design and operation of the utility boiler furnace and the type
of coal that is combusted (Joshi and Lohtia, 1997). There are four general types of coal-
11
fired boilers used in power plants: dry-bottom boilers, wet-bottom boilers, cyclone
furnaces, and stokers. Dry-bottom boilers are the most commonly used, as they are able
to burn coal with a wide range of ash fusion temperatures (Gainer, 1996). Wet-bottom
boilers, on the other hand, are more appropriate for burning coal that has lower ash fusion
temperatures. Cyclone furnaces and stokers are more infrequently used, and, in the case
of stokers, limited to older power plants and smaller generation loads. A schematic for a
typical dry-bottom pulverized coal utility boiler is shown in Figure 2-2.
From Beér, 2000)
Figure 2-2: Pulverized coal utility boiler schematic
12
Fly Ash Production
Upon combustion of pulverized coal in a dry-bottom boiler, 80-90% of the ash
leaves the boiler as fly ash in the flue gas. This high percentage is a result of the
extremely fine consistency of coal after being pulverized, as well as the low specific
gravity of ash in the dry-bottom boilers (Gainer, 1996). In wet-bottom boilers and
stokers, only 50% of the ash leaves as fly ash, with the remaining 50% retained in the
boiler. The lowest percent of exiting fly ash, 20-30%, is produced from a cyclone
furnace, as the cyclone boiler burns larger coal particles that do not undergo precombustion pulverization (Babcock and Wilcox, 1978).
Regardless of the type of boiler used, the fly ash, a fine-grained particulate, is
carried out of the boiler in the flue gas and is separated from the air stream by air
emission control (AEC) devices to minimize its release to the surrounding atmosphere.
The ash-laden flue gas can first pass through a mechanical AEC device, such as a
cyclone, that exerts centrifugal force on the ash particles in the gas stream, causing large
particles to leave the bulk air stream and collide with the collection device wall, where
they are removed. Ash particles can also be removed by electrostatic precipitators
(ESPs), an emissions control device used in over 1,300 installations to service 95% of
U.S. coal-fired electric utilities (Shnelle and Brown, 2002). This type of emissions
control device creates a charge on ash particles, applies an electric field to draw the
particles out of the bulk stream onto grounded plates, and then removes the dust that has
accumulated. The efficiency with which the particles are removed is proportional to the
magnitude of the applied electric field force and the charge on the particles. ESP
efficiency is very high, on the order of 99% capture of large particles (greater than 10
13
microns in diameter) and 90% removal of smaller particles (between 0.1 and 1 micron in
diameter) (Shnelle and Brown, 2002).
While not as widespread as ESPs, some utilities use baghouses to control
particulate and ash emissions from the flue gas stream. Baghouse is the common term for
a device containing fabric bags, used to filter particles from the gas stream, and a dust
collection and removal system. The fabric filters effectively capture particles 50-75
microns in diameter and greater through impaction and interception mechanisms and
particles with diameter of 1 micron and less through a diffusion mechanism (Shnelle and
Brown, 2002). Although this versatility generally results in baghouses that are 95-99%
efficient at controlling coal-fired power plant emissions, this control device is used only
in about 120 applications nation-wide (Merritt and Vann Bush, 1997). Wider application
of baghouse technology is limited by costs, including those of purchasing expensive
fabric for high temperature application, replacing used bags, operating over high pressure
drops, and maintaining dust removal over a variety of particulate conditions. However, it
is possible that baghouse use will rise with potential future legislation and increasingly
stringent regulations on emissions of air toxics and particulate matter (Merritt and Vann
Bush, 1997, Easom et al., 1999).
After treatment with various particulate control devices, the flue gas exits the
system into the atmosphere with reduced particulate matter. The exiting exhaust stream
still contains aerosols, organic and inorganic chemicals in the gas phase, and particulates
with very small aerodynamic diameter (less than 1 micron). The primary particles
escaping AEC devices are solid glass spheres and fine particles, which are created at high
combustion temperatures by condensation of volatile metallic and nonmetallic oxides and
14
the bursting of interstitial water and carbon dioxide bubbles through suspended mineral
grains (Ondov and Biermann, 1980).
Bottom Ash and Boiler Slag Production
While fly ash is being removed in the flue gas from the boiler, the remainder of the
ash content is collected from the boiler as either bottom ash or boiler slag. Bottom ash is
created in dry-bottom boilers and stokers, when remaining ash settles to the bottom of the
boiler, where it is collected for storage. Alternatively, in wet-bottom boilers, the
combustion temperature is higher than the ash fusion temperature, and therefore the ash
material exists in a molten state (Babcock and Wilcox, 1978). This molten material is
removed from the boiler into water-filled quench tanks or hoppers, at which point the
molten slag deposits undergo rapid cooling and subsequently fracture, crystallize, and
form coarse, black, angular, glassy pellets known as “boiler slag.” Boiler slag is also
produced by cyclone boilers, which use large pieces of source coal and operate at high
combustion temperatures.
Flue Gas Desulfurization Material Production
FGD material is produced by air emissions control devices designed to remove SO2
from the flue gas. These devices are needed because sulfur in the source coal is oxidized
during combustion to form SO2, a small fraction of which, about 1-2%, is further
oxidized to SO3 (Beér, 2000). SO2 is a federally and state-regulated criteria pollutant that
must be removed before flue gases can be released into the atmosphere. FGD units have
been used to remove SO2 chemically since the early-to-mid 1980s at coal-fired power
plants subject to the Federal New Source Performance Standards (NSPS) (Rubin et al.,
1986). NSPS are technology-based standards applicable to new and modified sources of
regulated air emissions. Installation of FGD scrubbers at electric utilities has been the
15
predominant means to ensure compliance with emission limitations on SO2. All FGD
scrubber systems operate based on a chemical reaction with a sorbent to remove SO2
from the exhaust air stream. Scrubber systems are usually classified as “wet” or “dry”
systems, and the type of system operation dictates the properties and quantities of the
final FGD material generated. FGD systems can also be classified as regenerable or nonregenerable systems, based on the ability to treat, retain, and reuse the sorbent after
desulfurization (Electric Power Research Institute [EPRI], 1999). In non-regenerable
systems, which are the most common type, SO2 is permanently combined with the
sorbent and must be treated as a waste or sold as a commercial product (Institute of Clean
Air Companies [ICAC], 1995). Regenerable systems have the capacity to release SO2 in
a regenerative process following sorption and to recycle sorbent back to the scrubber.
SO2 recovered from this type of scrubber system can be used to obtain sulfuric acid,
elemental sulfur, or liquid sulfur dioxide (Srivastava et al., 2001).
Wet, non-regenerable FGD scrubbers are the most common of SO2 emissions
control devices, as they are extremely effective (achieving over 95% reduction of SO2)
and thus desirable for units burning high sulfur coal (ICAC, 1995). These systems
remove SO2 by contacting a liquid sorbent, containing lime and limestone reagents, with
the exhaust gas and trapping SO2 in slurry form, also known as scrubber sludge. Natural
oxidation of the scrubber sludge with available air in the flue gas produces calcium
sulfite, while forced oxidation by excess air generates calcium sulfate dihydrate, or
gypsum, a saleable byproduct commonly used in wallboard manufacture (EPRI, 1999).
However, because of their use of water, wet FGD systems also produce larger volumes of
wastewater and sludge than dry systems (Rubin et al., 1986).
16
Dry FGD systems, on the other hand, are used primarily by electricity-generating
units that burn coal with lower sulfur content but that are still above regulated SO2
emission levels (Gainer, 1996). There are three main categories of dry scrubber systems:
spray dryers, circulating spray dryers, and dry injection systems. In spray dryers, the hot
flue gas is intimately contacted with an atomized slurry of alkaline reagents that
simultaneously absorb and dry SO2 in the flue gas from contact with the hot gases (EPRI,
1999). The dry product is then removed with the fly ash in an ESP or baghouse.
Circulating spray dryers use similar chemical principles as the spray dryer alkaline
sorbent combination described above by using hot flue gases to absorb SO2 from the gas
stream (ICAC, 1995). However, this method also uses an entrained fluidized bed reactor
for enhanced gas-solid mixing. The FGD product in this system is also removed with fly
ash in subsequent AEC devices downstream of the scrubber. Finally, dry injection
systems operate by inserting a dry sorbent, usually lime or limestone, into the flue gas
exiting the furnace boiler (Rubin et al., 1986). Again, the dry products are removed with
fly ash and other particulate matter in the subsequent AEC devices. Because the sorbent
enters the process inline with the boiler, an additional FGD reaction vessel is not required
for this process, thus decreasing the system’s capital costs (Srivastava et al., 2001).
However, dry injection has lower reagent utilization than the two former systems, and as
a result, higher raw material and operating costs offset capital savings (ICAC, 1995).
Based on these economic factors, dry injection systems are more commonly used at
smaller electric utility facilities or at facilities with lower SO2 removal required (ICAC,
1995).
17
Characterization of Coal Combustion Products
Fly Ash
Fly ash is the term generally used to describe the ash and non-combustible minerals
that are released from coal during combustion and that “fly” up and out of the boiler with
the flue gases (Halverson et al., 2001). The main constituents in fly ash are oxides,
sulfates, phosphates, partially converted dehydrated silicates, and other inorganic
particulate matter residual from coal combustion (Ledesma, 1990). Physically, fly ash is
made up of fine, powdery particles, which are predominantly spherical, solid or hollow,
and generally in an amorphous state, although uncombusted carbon in fly ash is usually
in the form of angular solid particles (Turner Fairbanks Highway Research Center
[TFHRC], 2002). Fly ash has a specific gravity between 2.1 to 3.0 and a specific surface
area ranging from 170 to 1000 m2/kg, as determined by the Blaine air permeability
method, which measures fineness of a material based on its permeability to air under
specified conditions (ASTM C204, 1994).
Chemical properties of fly ash are much less consistent than physical properties, as
fly ash is an inherently variable material. Fly ash variability is due to widespread
differences in inorganic chemical constituents of the source coal, methods of coal
preparation, combustion conditions, furnace type, and the ash collection, handling, and
storage conditions at each utility site (McCarthy, 1990). Because no utilities may have
all these factors in common, fly ash from different facilities is likely to vary significantly.
Even within one power plant, however, fly ash characteristics can change greatly over
time based on load and operating conditions over a 24-hour period (Joshi and Lohtia,
1997). Therefore, lack of fly ash consistency is a serious disadvantage for extensive and
economic ash utilization in beneficial uses.
18
Despite the uncertainty and variability of fly ash properties, some ash
characteristics can be correlated to the physical and chemical characteristics of the fuel
source, particularly coal. For example, bituminous coal fly ash is predominantly
composed of silica, alumina, iron oxide, and calcium, as well as a variable amount of
unburned carbon. On the other hand, subbituminous and lignite coal fly ashes exhibit
higher concentrations of calcium and magnesium oxide and lower amounts of silica and
iron oxide. These coals also usually produce fly ash with lower carbon content than that
of anthracite (TFHRC, 2002).
Fly ash color generally varies from tan to gray to black, as a direct function of the
carbon content remaining in the ash (Singh and Kolay, 2002). Ash from lignite or
subbituminous coal is generally tan to beige in color, indicating a low carbon content and
the presence of lime or calcium. Bituminous coal fly ash contains higher unburned
carbon and is therefore a shade of gray. Lighter tints of gray can indicate higher quality
ash (TFHRC, 2002). Indicated by the fly ash color, the quantity of unburned carbon
carried over from combustion into the fly ash is measured by the loss on ignition (LOI).
High LOI values are undesirable, as they indicate that the combustion of the source coal
is incomplete and raw material is being carried through to a waste stream rather than
being utilized for energy production. LOI is also a significant chemical property of fly
ash and serves as a primary indicator if an ash will make a suitable replacement for
cement in concrete production. Fly ash used as a cement replacement is required by
ASTM C618 to have below 6% carbon content, but it is preferred by members of the
cement and concrete industry to have at or below 3% carbon (Swanekamp, 2002).
19
Fly ash is also a pozzolan: a silica-, alumina-, and calcium-based material that has
potential to chemically combine with free lime (CaO) and water to produce a highly
cementitious, water-insoluble material (Western Region Ash Group [WRAG], 1998).
Pozzolanic behavior, as measured by the Pozzolanic Activity Index, is also influenced by
the fine particle size and amorphous nature of the fly ash (TFHRC, 2002). In some cases,
the calcium content of a given fly ash is high enough for the ash to be considered selfcementitious, or self-hardening, when mixed with water alone (ACAA, 1999). These
properties make fly ash a desirable substitute for Portland cement in concrete production
and other construction uses, as pozzolanic reactivity is necessary in such applications
(Dienhart et al., 1998; Gadalla et al., 1990; Joshi and Lohtia, 1997).
ASTM C618 groups pozzolanic material into three classes: N, F, and C. Class N
refers to natural pozzolans, but Classes F and C differentiate between fly ashes of
different chemical and physical properties. Class F is composed of ash produced from
burning lignite or bituminous coal (Boral Material Technologies, 2000). This class
exhibits pozzolanic reactivity but seldom shows any self-cementitious behavior. Class F
fly ash is also termed “low calcium ash,” as it contains less than 6% calcium oxide (CaO)
by weight (Phoenix Cement Company, 2003). On the other hand, Class C fly ash is
generated from burning lignite or sub-bituminous coal and typically has higher
concentrations of CaO, generally above 15% by weight (Joshi and Lohtia, 1997). Class
C fly ash also exhibits both pozzolanic and self-cementitious behavior.
Bottom Ash and Boiler Slag
Bottom ash and boiler slag are the heavy, coarse, granular, incombustible particles
remaining in the bottom of coal-fired boilers (Stewart, 1997). Bottom ash is ash residue
from combustion in a dry-bottom furnace, consisting of fused ash particles with a size
20
distribution typically between 75 µm and 2 mm and a composition that depends heavily
on the coal source (Joshi and Lohtia, 1997). Bottom ash particles have very porous
surface textures that create potential for deterioration during collection, storage, handling,
and use (TFHRC, 1997). Compared to bottom ash, boiler slag has smaller and more
consistent particle sizes. Boiler slag containing trapped furnace gas is somewhat porous,
although slags typically have a smooth surface.
Bottom ash and boiler slag are similar in terms of chemical composition. Both
products are composed primarily of silica, alumina, and iron, as well as low amounts of
calcium, magnesium sulfates, and other inorganic materials (TFHRC, 1997). These
chemical characteristics are derived from coal source and not operating parameters.
Based on their chemical composition and wide range of sizes, bottom ash and boiler slag
are not pozzolanic like fly ash, and therefore, have more limited applications in the
cement and concrete industry (Joshi and Lohtia, 1997). Additionally, their corrosivity,
conferred by their high salt content and potentially low pH, limits the use of these
products in embankments, road base or subbase, or backfill, where potential to contact
metal structures exists (TFHRC, 2002).
Flue Gas Desulfurization Material
As discussed previously, the physical and chemical properties of FGD material
vary significantly with different methods of SO2 removal. In the case of FGD scrubbers
that are used before other air emissions control (AEC) devices, the scrubber residue
consists primarily of fly ash and spent sorbent (ICAC, 1995). On the other hand, for
systems that remove particulate matter and ash before FGD treatment, the quantity of fly
ash in the FGD material is significantly decreased. In addition to solids in FGD material
21
(usually present in the range of 5 to 10 percent) and excess or spent sorbent, calcium
sulfate and calcium sulfite are also present (EPRI, 1999).
Of the available sulfur from a wet scrubbing product, 20-90% can be calcium
sulfite product, with the remainder as calcium sulfate (TFHRC, 2002). The relative
contributions of the sulfate and sulfite products determine the type and quality of the
FGD material. Calcium sulfate, when present at a high purity, is also known as gypsum,
a material that also occurs naturally and that has widespread application in sheet rock
production, agricultural fertilizer, soil amendments, and Portland cement production.
However, the calcium sulfite product, Gypsite, has more limited market potential and is
usually disposed in landfills or surface impoundments (WRAG, 1998). Limitations of
FGD material with high concentrations of calcium sulfite result from the thixotropic
behavior of the material. A thixotropic material is one that appears to be solid, but
liquefies when agitated. This property of high sulfite FGD sludges leads to poor settling
and filtering and makes the material less desirable for land application or other beneficial
use (TFHRC, 2002). The conversion from calcium sulfite to the more manageable
calcium sulfate usually takes place as an optional forced oxidation step after flue gas
scrubbing. The state of the FGD material, in terms of relative contributions to total
available sulfur, also determines the physical and chemical properties of the material.
Oxidized FGD material is coarser and has a lower specific gravity than unoxidized
calcium sulfite material (Smith, 1992).
In addition to differences based on the oxidation state of the final product, the FGD
material can also vary due to a variety of handling systems. FGD material is generally
either stabilized by combining the scrubber sludge with a non-reactive material and/or
22
fixated by mixing the sludge with a reactive species to produce a more stable final
product (ICAC, 1995). For ease of handling, stabilized FGD material is then dried or
dewatered, while fixated FGD products is chemically reacted with lime to create a
cementitious material (TFHRC, 1997). For example, FGD material can be combined
with fly ash, bottom ash, and free lime to create a pozzolanic material known as Pozz-otec. This material exhibits cementitious behavior, with low permeability and leachability,
and increasing strength over time (Doerr, 2002).
The physical and chemical characteristics of the large-volume CCPs vary with
different production, storage, and handling processes at different utilities. However, a
generalized of the physical and chemical properties of fly ash, bottom ash, boiler slag,
and FGD material is presented in Table 2-2.
Table 2-2: Chemical and physical properties of large-volume CCPs
wt %
SiO2
Fly Ash
20-60
Al2O3
Bottom Ash
45-70
Boiler Slag
40-54
FGD Material
15-30
14-23
---
2-3
Fe2O3
CaO
CaCO3
1-30
---
2-14
0.4-15
---
10-14
1-22
---
--0-20
0-40
CaSO3
---
---
---
0-95
CaSO4
MgO
SO3
--0-6
0-4
--2-5
---
--5-6
---
-----
0.6-1
1-2
---
Na2O
0-4
K2O
0-4
Appearance
Fine powder
Color
Light tan to dark gray
Shape
Mostly spherical
Size
< 0.0625 mm
Specific gravity
2.1 to 3.0
0.3-0.1
0.1-1
--Coarse granules Smooth, glassy pellets
Clay-like powder
Dull gray to black
Shiny black
White to gray
Angular
Angular Powder or crystalline
0.075 to 2.0 mm
0.5 to 5.0 mm
0.04-0.05 mm
2.1 to 2.7
2.3 to 2.9
2.2 to 2.6
From EPRI, 1999; Joshi and Lohtia, 1997; Taha et al., 1995; TFHRC, 2002; WRAG, 2002.
Coal Combustion Product Generation Trends and Forecasts
As electricity demand and regulations on air emissions have concurrently grown,
combustion products from electric utilities have also increased. Technologies and
23
markets for CCP use in beneficial applications have also grown due to economic and
environmental stimuli. An overview of national trends in generation, disposal, and
beneficial use is shown for CCPs in Figures 2-3 through 2-6 (from Kelly et al., 2002).
70,000,000
60,000,000
Tons
50,000,000
40,000,000
30,000,000
20,000,000
10,000,000
19
6
19 6
6
19 8
7
19 0
7
19 2
74
19
7
19 6
7
19 8
8
19 0
8
19 2
8
19 4
8
19 6
8
19 8
9
19 0
9
19 2
9
19 4
9
19 6
9
20 8
00
0
Year
Fly ash produced
Fly ash used
18,000,000
16,000,000
14,000,000
12,000,000
10,000,000
8,000,000
6,000,000
4,000,000
2,000,000
0
19
66
19
68
19
70
19
72
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
Tons
Figure 2-3: Fly ash production and beneficial use trends
Year
Bottom ash produced
Bottom ash used
Figure 2-4: Bottom ash production and beneficial use trends
24
6,000,000
5,000,000
Tons
4,000,000
3,000,000
2,000,000
1,000,000
No
Data
19
66
19
68
19
70
19
72
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
0
Year
Boiler slag produced
Boiler slag used
Figure 2-5: Boiler slag production and beneficial use trends
30,000,000
25,000,000
Tons
20,000,000
15,000,000
10,000,000
5,000,000
No Data
19
66
19
68
19
70
19
72
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
0
Year
FGD material produced
FGD material used
Figure 2-6: FGD Material production and beneficial use trends
As shown in the previous figures, the relative percent of each product that is used
beneficially varies significantly among the products. Although fly ash is produced in the
greatest amounts, a relatively small fraction is then used in beneficial applications. On
the other hand, boiler slag, produced in lower volume and with lower quality, is used in
large quantities. Greater use of boiler slag can be attributed to its functionality for highvolume, low-value applications that have minimal regulatory restrictions, such as in
25
blasting grit, (Gainer, 1996). Inversely, fly ash and bottom ash are used most frequently
in the construction industry where their use is subject to more stringent industry standards
and building and construction codes. Trends in the percentage of each type of CCP used
in beneficial applications are shown in Figure 2-7 (from Kelly et al., 2002).
Percentage of CCP Utilized
100%
90%
Boiler
Slag
80%
70%
60%
50%
40%
30%
20%
10%
Bottom
Ash
Fly Ash
FGD
19
66
19
68
19
70
19
72
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
0%
Year
Figure 2-7: Trends in percentage of CCP used, by type of product
Coal Combustion Product Disposal
While a significant fraction of the total CCPs generated is being beneficially used,
the majority of these products are still being disposed of in landfills and surface
impoundments. Based on increasingly stringent environmental requirements, all modern
RCRA Subtitle D landfills are required to have a liner, leachate collection system, gas
control system, and daily and post-closure permanent covers. However, as CCPs often
fall into special or industrial waste categories, electric utilities are usually granted
exemption from managing the CCPs as solid waste and are allowed to dispose of them in
26
on-site facilities. These onsite landfills are designed to minimize impacts on the
surrounding environment by a siting process that includes topographic mapping, site
reconnaissance, environmental inventory, and surface water and groundwater studies
(EPRI, 1999). These facilities and their governing regulations vary considerably from
state to state, but are often regulated with less stringency than typical solid waste disposal
facilities. For example, many states only recommend (but do not mandate) the use of a
composite or double liner with specific permeability standards (Woodward-Clyde, 1994).
CCP disposal also depends on the type of product generated at each utility as well
as the means of handling, transportation, and storage. Depending on the design of the ash
handling system, the fly ash may be combined with bottom ash. Bottom ash is quenched
upon removal from the boiler, and the resulting mixture of the two ashes contains water.
The solids content of the mixture should be maintained at optimal levels (75-85% of the
mixture weight) to ensure optimal transportability, afforded by the prevention of fugitive
dusting, elimination of thixotropic behavior, and avoidance of premature pozzolanic
reaction (Goodwin, 1993). Outside of this optimal range, mixtures with 50-65% solids
exhibit viscous behavior, mixtures with 65-75% solids are thixotropic, and mixtures with
greater than 85% solids cause dusting (Goodwin, 1993).
Fly ash that is handled independently of bottom ash is usually stored dry in silos
initially, with further storage or disposal in dry or wet form. Fly ash can be combined
with water for ease in stockpiling, landfilling, or sluicing into surface impoundments.
Another advantage of handling fly ash in a wet form is the reduction of blowing or
dusting during transportation and storage, although the resulting product has higher mass
and volume. Surface impoundments, the receptacles of the slurried ash, are also known
27
as settling basins or ponds and usually store a mixture of utility process wastewater and
CCP sludge. At some utilities, surface impoundments are temporary holding areas for
ash and slag products that are designated for harvesting later for beneficial use
applications or final disposal in a landfill (Stafford, 2003). However, it has been shown
that interactions between ash and water in a surface impoundment can produce
transformation of the physical, chemical, mineralogical, and geotechnical ash
characteristics, such that it may not be suitable for some beneficial uses (Singh and
Kolay, 2002).
Disposal of CCPs in landfills and surface impoundments presents a great deal of
uncertainty as to long-term human and environmental health effects, if any. One issue in
particular is that of trace element migration from the CCPs as leachate or runoff into
surrounding ecosystems. Coal is known to contain almost all of the naturally occurring
elements and, therefore, it follows that the coal ash and other combustion products would
be enriched in major and minor elements, the highest concentrations being those for Si,
Al, Fe, Ca, C, Mg, K, Na, S, Ti, P, and Mn, in decreasing order (El-Mogazi et al., 1988).
The presence of these high abundance metals indicates the likelihood that trace elements
will also be present from isomorphous substitution or random inclusions within the
crystal lattice of major elements (Krauskopf and Bird, 1994). As a matter of fact, thirteen
elements observed in coal (As, Be, Cd, Cl, Co, Cr, Hg, Mn, Ni, P, Pb, Sb, Se) are listed
as hazardous air pollutants (HAPs) as defined by Clean Air Act Amendments of 1990
(CAAA) (CAAA, 1990; Demir et al., 2002).
Extensive study has focused on the possibilities and potential impacts of xenobiotic
(specifically trace metal) transport from CCPs, particularly from fly ash and bottom ash
28
disposal. Generally, trace element concentrations in CCPs increase with a decrease in
ash particle size and subsequent increase in particle specific surface area, with
concentration of more volatile trace elements on the ash particle surface (Adriano et al.,
1980). The primary concern with these compounds, 90% existing in their inorganic form,
is their potential to leach into surface water or groundwater and subsequently accumulate
in and affect the biota surrounding disposal sites (Khandekar et al., 1999, Mukherjee and
Kikuchi, 1999). For example, it has been observed that Al, As, B, Ba, Cs, Rb, S, Se, Sr,
W, and V concentrations increase in plants and vegetation with increasing ash application
(Adriano et al., 1980). However, results from the inquiry into trace element
concentration and mobility vary significantly between different locations and different
types of CCP. The U.S. EPA has determined that leaching from CCP disposal does not
present significant risk to human or environmental health and that utilities are trending
towards disposal facilities with adequate provisions for controlling CCP leaching or
groundwater impact (U.S. EPA, 2000). However, this assessment is largely based on
disposal in landfills, whereas nationally and in Florida, utilities are also likely to use
surface impoundments for disposal and temporary storage, as the impoundments often
require less construction time and expense, are not regulated as strictly as landfills, and
have fewer site-specific constraints (Woodward-Clyde, 1994).
Coal Combustion Product Beneficial Use Opportunities
As indicated previously, there is a substantial environmental and economic case to
be made for beneficial use of CCPs rather than traditional disposal options. However, as
shown by the historical trends of CCP generation, use, and disposal, there is still a great
deal of room for improvement in the percent of each CCP used in beneficial applications.
In addition, there are numerous barriers to increased use of combustion products,
29
including the lack of standards or guidelines for specific applications, transportation costs
of shipping CCPs to markets, and potentially increasingly restrictive regulatory controls
of CCPs and potential uses (Kalyoncu and Olson, 2001). Nevertheless, a large body of
knowledge has been created in academia, industry, and government regarding the
beneficial use of CCPs in numerous applications. Several of the most common current
uses and the most promising future applications will be discussed here.
Concrete Products
The cement and concrete industry represents the largest share of total CCP use,
particularly for fly ash, as it accounts for 35% of all CCPs and 53% of fly ash beneficially
used (ACAA, 2000). When fly ash from coal combustion is combined with moisture
(water) and a free lime source such as calcium hydroxide, a pozzolanic reaction occurs to
form the same calcium-silicate-hydrate that is found in commercially available cement
(Halverson et al., 2001). Therefore, fly ash is used as a substitute for about 20-30% of
the Portland cement traditionally used to make concrete. The development of strength in
concrete made from a fly ash blend is a function of the particle size distribution and glass
content of the fly ash, the mix design, and the relative humidity and temperature during
curing (Gadalla et al., 1990; Pratt, 1990). Long-term concrete performance has been
shown to be affected by both physical and chemical properties of the fly ash used. The
most influential properties include ash particle size, loss on ignition, specific gravity,
moisture content, free lime, silicates, aluminates, iron oxide, carbon, ash mineralogy, and
morphology (Joshi and Lohtia, 1997).
The long-term effectiveness of fly ash in cement and concrete applications has also
been verified. In one experimental trial, two sections of a reinforced concrete bridge, one
composed solely of Portland cement and the other of a 25% fly ash/75% Portland cement
30
blend, were compared for strength over a ten-year period. The fly ash concrete had
continued to gain in strength throughout the ten years, demonstrating the beneficial
effects of fly ash. Additionally the fly ash concrete had significantly lower oxygen and
water permeability than the Portland cement concrete (Pratt, 1990).
Fly ash is an economically desirable option for this application, at costs on the
order of $20 per ton, as opposed to Portland cement costs of $50-90 per ton, excluding
transportation costs (Gainer, 1996). In addition to economic incentives, the use of fly ash
has also been touted as a way to reduce energy required in cement and concrete
production. Recently, it has been determined that fly ash addition to or partial
substitution of Portland cement may result in technical benefits like improved resistance
to Alkali-aggregate reaction; conversion of Ca(OH)2 (the most soluble product of
Portland cement hydration) to more stable calcium silicate hydrate; improved water and
gas tightness; lower creep and shrinkage; favorable pore size distribution; and improved
workability for decreased water demand (Mills, 1990). Additional benefits of fly ash
addition to concrete included improved strength, durability and placement properties,
greater long-term strength gain, improved sulfate resistance, lower heat of hydration,
lower permeability, lower water demand, increased resistance to alkali reactivity, and
enhanced workability (Dienhart et al., 1998).
Beneficial use of fly ash in concrete and cement does have added challenges,
however. These challenges include the need to acquire, store, and handle an extra
material; increased dosage of additives, such as air entraining agents; increased setting
time and slow hardening, particularly at lower temperatures; and the need for additional
curing (Mills, 1990). An additional impediment to fly ash substitution for Portland
31
cement is the limit on unburned carbon present in the ash, as measured by loss on ignition
(LOI). LOI is considered one of the most important quality indicators of fly ash being
used for concrete production. High LOI (>6%) is typically associated with creation of an
unstable level of air entrainment in concrete, potentially decreasing concrete durability
and/or strength (Hill et al., 2001).
As discussed previously, ASTM standards dictate unburned carbon content as
measured by LOI to be less than 6% of the fly ash by weight (ASTM C618, 1994).
Unburned carbon has the potential to create aesthetic discoloration in the finished cement
product, poor air entrainment in mixing, and segregation of mixing components (Gainer,
1996). Of these issues, air entrainment is the most significant, as it controls workability
and cohesion of concrete mixes as well as the water content and resistance to the freezethaw cycle of the concrete product (Joshia and Lohtia, 1997). Ironically, however,
increasingly stringent air emissions regulations may indirectly result in an increase of the
LOI content in most fly ash produced from coal-fired utilities. The Clean Air Act
Amendments of 1990 require drastic reductions in NOx emissions from utilities.
Reductions of thermal NOx require decreasing the combustion temperature with
combustion control technologies, such as low NOx burners, staged combustion, or
reduced excess air (Shnelle and Brown, 2002). However, many of these technologies
also have the downside of decreasing the conversion of carbon in the coal, which
subsequently decreases energy production and creates higher carbon-content ash
products. Thus, the challenges of high-carbon ash must be approached from both the
electricity generation and the ash utilization perspectives for future studies. Nevertheless,
it is predicted that use of all CCPs in concrete and cement will continue to increase by an
32
average 8% per year as acceptance and marketability of these products continue to grow
(Gainer, 1996).
In addition to fly ash substitution for Portland cement in concrete production, there
are many other beneficial uses of CCPs in the cement and concrete industry. One such
use is the creation of bricks, block, and tile from fly ash. Brick and block materials made
from fly ash have demonstrated higher strength, lower thermal conductivity, and lower
density than traditional clay bricks (Gainer, 1996). These advantages translate into
economic benefits as well: reduced transportation and installation costs, decreased energy
requirements, and reduced cost of raw materials.
Aggregates
Ash has also been successfully used as an insulating building material and as a
replacement for conventional stone and sand in lightweight aggregate production.
Generally, bottom ash is used as a lightweight aggregate in the production of precast
concrete products, such as concrete blocks or masonry units (Dienhart et al., 1998). Fly
ash can also be used or blended with bottom ash in a chemical or heat-treatment bonding
process, such as production of AardeliteTM pelletized aggregate (Craig, 2003). These
CCPs are used as lightweight aggregate when low weight of the final product is an
important factor in structural design and performance as lightweight aggregate has a
density averaging 50 to 70 lbs/cu.ft (Dienhart et al., 1998). Ash-based aggregate is up to
50% lighter than conventional aggregate and significantly reduces building loads when
used in structural concrete, masonry, and decorative applications (Gainer, 1996).
However, ash-based aggregate is limited by the relatively inexpensive nature of
competing conventional materials, such as sand and gravel.
33
Autoclaved Cellular Concrete
A promising application of ash in the concrete and cement industry is the
production of autoclaved cellular concrete (ACC) blocks. These blocks are manufactured
by mixing Portland cement, lime, aluminum powder, and water with a silica-rich
material, such as fly ash (Dienhart et al., 1998). Increased use of ACC blocks has the
potential to reduce heating bills in residential and commercial buildings, as research has
shown that fly-ash-based ACC possesses superior insulating capabilities compared to
conventional concrete (Valenti, 1995). ACC blocks can contain up to 70% ash, and the
resulting products are extremely light and easy to work with (EPRI, 1999). In addition,
these blocks are 75% lighter than conventional concrete blocks and can be drilled, sawed,
chiseled, and nailed with woodworking tools, thus reducing construction time and labor
(Gainer, 1996).
Road Base and Subbase
Fly ash, bottom ash, and mixtures of these two CCPs and other materials have been
successfully used as raw materials in the construction of roads, among other paved
structures. Lime-fly ash mixtures and cement-treated bottom ash can be substituted for
traditional materials like crushed stone or gravel as base courses beneath pavements or on
secondary roads (Dienhart et al., 1998). These base and subbase layers improve the
stability, compressibility, durability, and permeability of the soil on which the paved
surface is being constructed (Ferguson and Levorson, 1999). Field tests of lime-fly ash
as a replacement for a soil base course in flexible pavement systems have demonstrated
that the fly ash mixture is less prone to shrink, crack, or develop aesthetic problems, but
has lower initial strength, as compared to a traditional base material (Shirazi, 1999). Fly
ash has also been shown to be a suitable stabilizing agent in a road base course
34
constructed from industrial byproduct gypsum (Gadalla et al., 1990). Almost one million
tons of fly ash and 600,000 tons of bottom ash were used as road base and subbase
materials in 2001 (ACAA, 2003). However, state and national transportation and
environmental agencies are still apprehensive of widespread CCP use in road
construction because of the lack of data on environmental performance and health
impacts from such applications (Rehage and Schrab, 1995).
Use of fly ash mixtures for base and subbase is desirable over traditional materials
when improved strength and durability are required in pavement construction, while
bottom ash is favored based on its relative inexpensiveness and abundance, as compared
to conventional materials (Dienhart et al., 1998). Additionally, FGD scrubber sludge has
been used successfully in this application by fixation with lime and ash to create a
pozzolanic base course under traditional asphaltic paving (Rehage and Schrab, 1995).
Traditionally, use of CCPs for road base and subbase has been limited to secondary roads
in rural locations due to the uncertainties associated with environmental and human
health impacts derived from applying these products directly to land by mixture with
soils (Atalay and Laguros, 1990). The State of Texas is one area in which inquiry into
this beneficial use application is particularly strong and growing (Texas Transportation
Institute [TTI], 2000)
Concrete and Asphaltic Concrete Pavements
In addition to road base and subbase, fly ash can also be used in the concrete and
asphaltic concrete pavements that make up the surface of the roads, bridges, parking lots,
and other paved surfaces. In the case of concrete pavement, fly ash is a desirable
pozzolanic component as its use improves workability and packing, decreases water
demand during production, reduces the permeability of the concrete to chlorides, and
35
increases resistivity to corrosion, as compared to concrete produced without fly ash (Obla
and Halverson, 2002). On the other hand, fly ash in asphaltic concrete pavements is not
used as much for its pozzolanic properties, but instead as mineral filler because of its
primarily alumino-silicate composition, low plasticity, and fine grain size (Dienhart et al.,
1998). Bottom ash can be used in asphaltic concrete flexible pavements as a partial
replacement for other types of aggregates. In this application, performance of the
pavement is in compliance with strength and durability requirements, but somewhat
lower than that of concrete made with traditional aggregates, indicating that the use of
bottom ash is suitable for parking lots, driveways, and secondary roads with low traffic
rather than high traffic highways (Churchill and Amirkhanian, 1999; Dienhart et al.,
1998).
Structural Fill and Embankments
Fly ash and bottom ash have found considerable industry acceptance and use in
applications for structural fills. This application is unique in that all four of the largevolume CCPs can be used in significant quantities as structural fills (Gainer, 1996).
Structural fills are required in construction or engineering applications to provide a level,
strong, and highly compacted base on which an engineered structure will be built.
Examples of these uses include construction of highway embankments, pipe bedding, and
backfilling of abutments, retaining walls, or trenches (TFHRC, 2002). In these
applications, CCPs replace soil or gravel that would otherwise have to be excavated and
transported from potentially large distances. Fly ash and bottom ash used in
embankments have been shown to have equal or better performance over other materials
(such as soils) used for this application, with the added benefit that their light weight
limits embankment settlement on soft subgrades (Martin et al., 1990). Additional
36
benefits of CCP use include that they are available in bulk quantity, have higher slope
stability factors of safety, have high shear strength to unit weight ratio, result in more
ideal placement under a structural foundation, and produce a free draining fill (Butalia
and Wolfe, 2000). Based on these factors, structural fills currently account for over 14%
of the total CCPs beneficially used (ACAA, 2000). This percentage is the second highest
for beneficial use after concrete and cement products.
Flowable Fill
Flowable fill, on the other hand, only accounts for a little over 2% of total CCP
beneficial use, according to the most recent American Coal Ash Association industry
survey (ACAA, 2003). However, it is predicted that current interest from industry and
favorable research findings will result in a 25% increase each year in the use of CCPs in
flowable fill (Gainer, 1996). Flowable fill is a low strength material that usually contains
a mixture of fly ash, Portland cement, sand, and water and is used in construction and
engineering applications, where it is designed to flow quickly into place and set fast, but
still maintain controllable strength in case of possible future excavations (Butalia et al.,
2001). Flowable fill is also known as controlled density fill, controlled low strength
material, unshrinkable fill, flowable mortar, and plastic-soil cement. Applications of
flowable fill include backfilling (e.g., sewer trenches, utility cuts, bridge abutments,
conduit trenches, pile excavations, and retaining walls), stabilizing foundation subbase,
road base, and embankment slopes, filling abandoned storage tanks, and grouting wells
(Naik et al., 1990).
There are numerous advantages for using CCPs in flowable fill applications.
Primarily, the quality of ash used in flowable fills does not require the strict control on
LOI and quality necessary in other cementitious applications. In addition, dry and
37
reclaimed fly ash and bottom ash can be used with no added processing or moisture
control required (TFHRC, 2002). Field tests of a flowable fly ash slurry fill demonstrated
excellent flowability, high compressive strength, and light final weight that minimized
settlement (Naik et al., 1990). Other work involving lime- and/or cement-stabilized fly
ash also has shown that these mixtures increased strength and durability and decreased
permeability and leachability in flowable fill, as compared to using compacted soil (a
traditional fill material) in the same application (Gabr and Bowders, 2000). Although ash
is the predominant CCP used in flowable fill, research has shown that FGD material is
also suited to this beneficial use. FGD fill has been observed to be comparable to
traditional flowable fill with the added benefits of low unit weight, good shear strength,
and lower raw material costs (Butalia et al., 2001).
Manufactured Products
In addition to the large and diverse market for CCPs in cement and concrete
production and engineered structures construction, these products have also made a
considerable market presence in specialty applications, particularly as substitutes for raw
material in manufactured products (Gainer, 1996). Some of the highest volume existing
and emerging markets for CCPs in manufactured products are discussed below.
Roofing granules and blasting grit
Roofing granules are the hard, fine aggregates used in shingles and other roofing
products. In this application, boiler slag is a preferred material, based on its glass-like
composition, naturally dark color, hardness, and resistance to ultraviolet radiation (Demir
et al., 2001; Dienhart et al., 1998). Furthermore, use of boiler slag has been shown to
prevent color fading and minimize aggregate pitting, as compared to conventional
aggregate materials (Bretz, 1991).
38
Processing boiler slag to produce roofing granules also generates the blasting grit
that can be used in sand blasting (Deinhart et al., 1998). The combined use of boiler slag
for blasting grit and roofing granules was just over 1.4 million tons in 2001 (ACAA,
2003). Bottom ash can also be used in this application. Both materials have hard,
abrasive surfaces that make them a durable, economical source for obtaining blasting grit
(Bretz, 1991). No literature has been found to show that there are any environmental or
health impacts associated with this beneficial use.
Wallboard
Wallboard is a common construction material used for interior walls, ceilings, and
other building applications. It is made by creating a plaster out of natural or manmade
gypsum and spreading it between two layers of heavy paper (National Gypsum
Company, 2003). Manmade gypsum, or phosphogypsum, is obtained as a byproduct of
wet phosphoric acid production and has been shown to contain elevated levels of
naturally occurring radiation (Taha et al., 1995). When gypsum formed by wet FGD
processes at utilities is oxidized at or above 99%, it is of the quality required to substitute
for phosphogypsum in wallboard production (Srivastava, 2001). Use of FGD gypsum in
wallboard is constrained by the requirements that the soluble salt and fly ash
concentrations be limited, to minimize delamination of the paper layer from the gypsum
core and to prevent discoloration and excess crystallization, respectively (Dienhart et al.,
1998). The environmental concern over use of FGD gypsum is focused on the possibility
that high sulfate concentrations, originating from gypsum storage and processing areas,
could enter surface waters. However, one of the major environmental benefits of FGD
gypsum use is the elimination of potential radiation risk associated with use of
phosphogypsum (Taha et al., 1995).
39
Cenospheres and filler in paint, plastics, and other products
Cenospheres are hollow, lightweight, inert, ceramic fly ash microspheres that form
one of the minor constituents of fly ash (Kolay and Singh, 2001). Cenospheres and fly
ash as a whole have both been used successfully as extenders in plastic compounds and
mineral fillers in paints, coatings, joint compound, roofing material, glass, carpet
backing, flooring, and nylon/polyester materials (Gainer, 1996). In addition to being
more economically viable than traditional raw materials, such as clay and calcium
carbonate, fly ash and cenospheres have the advantage of increased flowability and
resistance to high-temperature processing (Dienhart et al., 1998).
Fly ash use in paints has been shown to last longer, maintain higher levels of
aesthetic performance, and eliminate the thickening effect observed with other materials,
such as talc and titanium dioxide (Bretz, 1991). Fly ash has also begun to gain
acceptance as mineral filler in the manufacturing of plastics and production of material
out of post consumer recycled plastic (Leone and Makansi, 1995; Li et al., 1998). In
these applications, the hardness, chemical composition, and spherical shape of fly ash
reduces thermal decomposition of plastic polymer chains, expedites the melting and
extrusion processes, reduces material shrinkage, and improves the strength and durability
of the final product (Bretz, 1991; Li et al., 1998). Innovative research on fly ash use has
proposed that coated cenospheres can be used to decrease radar echoes in the “stealth
aircraft,” making them less detectable (Dienhart et al., 1998). Fly ash has also been
examined as a possible raw material for producing glass and glass-ceramics. Recent
work has shown that fly ash can be vitrified to form a glass material that minimizes
leaching of any trace metals present; however, this product does not yet meet strength or
aesthetic requirements necessary to be manufactured as a commercially viable product
40
without additional research and development (Sheng et al., 2003). Yet, fly ash has been
successfully used as raw material in experimental manufacturing of glass-ceramics, such
as street plates, floor tiles, or decorative tiles (Barbieri et al., 1999; Cimdins et al., 2000).
Such an application also has the benefit of immobilizing trace metals and other impurities
by vitrification.
Agricultural and Environmental Applications
An increasing amount of CCPs has been used in agricultural and environmental
applications. Each year, almost 1.5 million tons of CCPs have been used for waste
stabilization and treatment, and about 150,000 tons of this material has been used as an
agriculture and soil amendment (ACAA, 2003). These applications take advantage of the
physical and chemical properties of CCPs to enhance crop production and improve waste
management methods.
Soil amendment
CCPs, especially ash and FGD material, have been used in limited quantities as
agricultural fertilizers and soil amendments. Although this use accounts for less than 1%
of all CCP beneficial use, it has been documented as a viable way to improve soil
properties and increase crop production (ACAA, 2003; Rechcigl, 1998). The continual
use of inorganic nitrogen fertilizers on agricultural land can reduce soil pH, which
decreases some plant growth but can potentially be remedied by the use of alkaline CCPs
as liming agents (Canty and Everett, 2001). Additionally, ash and FGD gypsum have
been found to provide certain nutrients otherwise unavailable naturally to crops and to
increase soils’ water holding capacity and the subsequent amount of water available to
plants (Iyer and Scott, 2001).
41
Despite potential for more widespread use, agricultural applications for CCPs have
been limited by high transportation and application costs as well as the concern that the
products may contribute heavy metals and trace elements to the crops and surrounding
ecosystems (Gainer, 1996). A potential solution to this problem is combination of ash
products with FGD material. FGD sludge provides additional benefit to agricultural
lands by mitigating low pH problems, increasing nutrients available to plants, improving
water infiltration and soil aggregation, and ameliorating sodic soil problems (Clark et al.,
2001). Successful use of CCPs in land applications has also stemmed into horticultural
applications. Research completed by the Electric Power Research Institute (EPRI)
indicates that mixtures of fly ash, bottom ash, and biosolids have proven to be ideal
growth media for horticultural ornamentals and turfgrass sod, as the mixtures have low
density, a wide particle size distribution, resistance to decomposition, and high
availability in urban areas (EPRI, 2002).
Acid mine drainage and surface mine reclamation
Use of CCPs in treatment of acid mine drainage and in mine reclamation has been
the subject of great debate between the mining and the regulatory communities. CCPs,
particularly FGD material and fly and bottom ash, are often alkaline, such that they could
be used as neutralizing agents to treat acid mine drainage and prevent erosion and
subsidence caused by acidic conditions (Dienhart et al., 1998). One such technique,
alkaline injection technology (AIT), has been used to suggest that injection of alkaline
CCPs into inactive mines will neutralize the acid and raise the system pH, thus causing
metals present to precipitate out as carbonate and hydroxide complexes, lowering the
total metal load in the mine effluent (Canty and Everett, 2001). Approximately one
million tons of fly ash, bottom ash, and FGD material, combined, were used in mining
42
applications in 2001 (ACAA, 2003). However, because of existing questions concerning
the environmental impacts of use in this application, it has not yet found approval, much
less favor, by the U.S. EPA and most state environmental regulatory agencies. Therefore,
it will not be discussed in great detail here except to note that there is a body of research
dedicated to this topic (e.g., Canty and Everett, 2001; Carlson and Adriano, 1993; Demir
et al., 2001; Iyer and Scott, 2001; Sevim and Unal, 1998; U.S. EPA, 1999).
Daily landfill cover
Another prospect for CCP use in waste management is in the creation of landfill
liners or covers with ash and FGD material. Disposal sites regulated to have daily cover
use ponded ash as a means of preventing landfill gas emissions and dust problems
(Gainer, 1996). Conversely, protective landfill liners can also be created from FGD
scrubber sludge, fly ash, and lime. This type of liner costs significantly less than its clay
or geomembrane equivalents, as 95% of the raw material is derived from utility
byproducts (Rittenhouse, 1995). The economic value of CCPs for landfill cover is
governed by their fine grain size, making them a practical cover material in locations
where appropriate soils or other raw materials are scarce (Dienhart et al., 1998).
Waste stabilization
Chemical properties of some CCPs make them desirable for use in wastewater and
solid waste stabilization, neutralization, and management. This is particularly true of fly
ash, as waste stabilization is the third greatest use of fly ash and also represents 6% of the
beneficial use of all CCPs (ACAA, 2003). Important properties of CCPs for use in waste
treatment include the absorptive nature, the fine particulates and high surface area, and
the alkaline characteristics (Joshi and Lohtia, 1997). Based on these properties, ash can
43
be utilized through three mechanisms of waste treatment: 1) as a flocculant or an
absorbent to remove pollutants, 2) as a neutralizer to stabilize acid-base conditions, or 3)
as a pozzolan to solidify waste products and minimize pollutant transport (Dienhart et al.,
1998). Fly ash has been successfully shown to remove arsenic, cadmium, chromium,
mercury, cesium, and strontium from waste water by means of an absorption mechanism
(Iyer and Scott, 2001). The alkaline nature of fly ash and its ability to neutralize acid
wastes has shown positive results in removing heavy metals, such as nickel, cadmium,
chromium, lead, copper, mercury, and zinc from wastewater as well (Fly Ash Resource
Center [FRC], 2002). Experimental results have also shown that bottom ash could be
used as an adsorbent to remove hydrogen sulfide from landfill gas and to remove
phosphorous, iron (3+), manganese (2+), zinc (2+), chemical oxygen demand, and total
Kjeldhal nitrogen from landfill leachate streams (Lin et al., 2001).
One advantage of using fly ash as a waste treatment additive is its relatively low
cost, compared to traditional treatment materials, including activated carbon, metal
oxides, and ion exchange resins (Joshi and Lohtia, 1997). However, one disadvantage to
consider is that compared with neutralization using pure compounds, the use of CCPs
results in much higher quantities of solid by-product (Canty and Everett, 2001).
Therefore, when accounting for transportation and solid by-product disposal costs, the
use of CCPs for acid waste neutralization becomes somewhat less competitive with other
treatments.
Metals recovery
In many cases, fly ash and other CCPs can be used to extract metals and materials
that would else have to be obtained from mining and other extractive processes. The
process of combustion concentrates in the fly ash any trace elements originally present in
44
the source coal. Recovery of these metals not only represents a source by which they can
be obtained outside of raw material extraction, but it also removes them from the fly ash,
thus eliminating their potential for leaching and environmental contamination.
Experimental work has shown that fly ash can be treated chemically or thermally or by
particle size separation to extract high levels of iron, ferrosilicon alloys, gallium,
vanadium, nickel, magnesium, germanium, arsenic, cadmium, and zinc (Demir et al.,
2001; Gutiérrez et al., 1997; Iyer and Scott, 2001). This is another beneficial use market
that has potential for future growth, but that has not yet experienced the high levels of
success that has been shown in cement and concrete applications (Gainer, 1996).
A summary of the potential beneficial uses for each type of CCP is presented in
Table 2-3. This table also includes a designation if the CCP is commonly used in Florida.
Table 2-3: Beneficial use markets for CCPs in general and specific to Florida
Beneficial Use
Fly Ash
Bottom Ash
Cement/concrete/grout
3
3
Structural fill
3
3
Flowable fill
3
3
Waste stabilization/solidification
3
Agriculture
Boiler Slag FGD Material Use in Florida
3
3
3
3
3
3
3
3
3
3
Soil Amendment
3
3
Road Base/Subbase
3
3
Blasting grit/roofing granules
Mineral filler
3
Snow and ice control
3
3
3
3
3
3
3
3
Wallboard
3
3
3
Material Extraction
3
3
Mine filling/reclamation
3
3
3
3
3
Legislative History of Coal Combustion Products
Despite continued interest from industry and utilities, no CCP beneficial use
applications have reached their full potential, in part due to ongoing limitation by
45
regulatory constraints. From a Federal perspective, disposal of CCPs has a long and
complex regulatory history. However, a cohesive approach to regulating CCP beneficial
uses has not been developed on the Federal level, and has only recently been promulgated
by some states. A discussion of issues and history of CCP disposal and beneficial use
follows.
Federal Regulatory History of Coal Combustion Products
Solid wastes, including CCPs, are regulated at the Federal level under the Resource
Conservation and Recovery Act of 1976 (RCRA) and can fall under Subtitle C or D,
depending on whether they classify as hazardous or not. For over 20 years, there has
been great debate as to whether CCPs should be included in or exempted from regulation
under RCRA Subtitle C, which controls the identification, generation, handling, storage,
treatment, and disposal of wastes that either show hazardous characteristics or are listed
as being hazardous. There are over 200 hazardous materials listed in 40 CFR 261.10 and
261.11 as having one or more of the following characteristics: ignitability, corrosivity,
reactivity, and toxicity. However, CCPs are one of 18 materials that have been classified
as solid wastes that are exempt from regulation as a hazardous waste, according to 40
CFR 261.4. Should CCPs be included under RCRA Subtitle C, more stringent
requirements and limitations on their generation, use, and disposal would be imposed
than would be necessary under Subtitle D, which regulates nonhazardous solid wastes
that are then subject to individual state laws. The debate over regulating CCPs under
RCRA Subtitle C has been chronologically detailed below.
In 1976, the Resource Conservation and Recovery Act (RCRA) was passed.
Subtitle C of RCRA and its implementing regulations imposed specific Federal
requirements on hazardous materials. Subtitle D of RCRA delegated regulation of
46
nonhazardous solid wastes to the individual States. In its original form, RCRA did not
specify whether CCPs fell under Subtitle C or D.
In 1977, the Surface Mining Reclamation and Control Act (SMCRA) was passed.
Neither SMCRA nor its implementing regulations specifically addressed the use or
disposal of by-products of electric power generation at surface coal mines. The
regulatory authority, however, was involved to the extent that SMCRA requires the mine
operator to ensure that
1.
all toxic materials are treated, buried, and compacted, or otherwise disposed of, in a
manner designed to prevent contamination of ground water or surface water,
2.
the proposed land use does not present any actual or probable threat to water
pollution, and
3.
the permit application contains a detailed description of the measures to be taken
during mining and reclamation to assure the protection of the quality and quantity
of surface and ground water systems, both on- and off-site, from adverse effects of
the mining and reclamation process, also to assure the rights of present users of
such water are protected.
In December of 1978, the U.S. EPA proposed the rule to implement RCRA Subtitle
C and a limited set of regulations for management of certain large-volume fossil fuel
wastes. In October 1980, Congress passed the Solid Waste Disposal Act Amendments,
which temporarily exempted certain large-volume fossil fuel wastes (fly ash, bottom ash,
boiler slag, and flue gas desulfurization sludge) from regulation under RCRA Subtitle C.
This exception, in Section 3001(b)(3)(A)(i) of RCRA, which became know as the Bevill
Amendment, included a stipulation that U.S. EPA must conduct a comprehensive study
of fossil fuel wastes, based on the following eight study factors, required by RCRA
Section 8002(n), for fossil fuel combustion wastes (U.S. EPA, 1999):
1.
The source and volumes of such materials generated per year
47
2.
Present disposal practices
3.
Potential danger, if any, to human health and the environment from disposal of
such materials
4.
Documented cases in which danger to human health or the environment has been
proved
5.
Alternatives to current disposal methods
6.
The costs of such alternatives
7.
The impact of those alternatives on the use of natural resources
8.
The current and potential utilization of such materials
Congress also directed that within six months of completing this report, the U.S. EPA
must conclude whether CCP regulation under Subtitle C is necessary. Until that time,
CCPs were subject to regulation under State laws on solid waste.
In 1984, the RCRA Hazardous and Solid Waste Amendment (HSWA) was passed,
giving the U.S. EPA flexibility to pass regulations under Subtitle C and to modify the
Solid Waste requirements based on the unique characteristics of CCPs, as long as health
and the environment were protected.
In February 1988, the EPA completed the report to Congress on exemption of
CCPs. However, because of other priorities, the Agency failed to publish the required
regulatory determination.
In 1991, a suit was filed against U.S. EPA by Bull Run Coalition (an Oregon
citizens’ group) and the Edison Electric Institute for its failure to complete the required
regulatory determination of CCPs (Gearhart v. Reilly Civil No. 91-2345 D.D.C).
48
In June 1992, the U.S. EPA entered a consent decree that established a schedule to
complete the regulatory determination in two categories: 1) the four large-volume wastes,
completed by August 2, 1993 and 2) all remaining wastes, by April 1, 1998.
In August 1993, the U.S. EPA made a regulatory determination that the four largevolume CCPs did not warrant regulation under RCRA Subtitle C. Additionally, the U.S.
EPA extended their schedule to allow for additional study and committed to completing
the report to Congress on mixed fuels and remaining wastes by March 31, 1999, with a
regulatory determination by October 1, 1999.
In March 1999, EPA submits their report to Congress, concluding that regulation of
mixed fuels or any remaining wastes will not be warranted under Subtitle C. However,
the Agency asserted that there was insufficient information on managing CCP disposal or
beneficial use in surface and underground mines to assess potential for risks associated
with this practice.
In March 2000, EPA drafted a report of findings that would no longer exempt
CCPs from Subtitle C for disposal or mine filling. It was approved that the deadline for
the U.S. EPA determination would be extended to April 10, 2000. In April 2000, EPA
drafted a proposal that opposed its findings in the March 1999 Report to Congress. The
new draft did not exempt mine filling as a beneficial use and required that for land
disposal or mine filling, even large-volume wastes could be subject to Subtitle C unless
managed properly.
By May 2000, the U.S. EPA made another reversal and presented the final
regulatory determination on CCPs, detailed below, which extended the Bevill
Amendment and fulfilled the requirements of RCRA Section 3001(b)(3)(A)(i). In the
49
final determination, the U.S. EPA upheld the 1993 exemption of large-volume coal, fuel,
and natural gas combustion products from utilities and non-utilities from regulation under
RCRA subtitle C. EPA did conclude, however, that wastes disposed of in landfills and
surface impoundments will be subject to future regulations under RCRA Subtitle D and
possibly subject to changes in the Surface Mining Control and Reclamation Act
(SMCRA), which regulates, on a site-specific basis, the filling of surface or underground
mines.
Reasons for this ruling included the trends of improving disposal practices (landfill
liners, gas collection systems, and groundwater monitoring), lack of evidence that fossil
fuel combustion wastes pose significant risks to human or environmental health, and the
desire to minimize any stigma or discouragement of beneficial use of CCPs (U.S. EPA,
2000). This ruling is subject to future changes in the event that waste management
practices do not continue to improve or maintain acceptable protection or that significant
threat to human or environmental health is exhibited.
The May 2000 ruling also differentiated between “uniquely associated” waste,
defined as that which contact a fossil fuel or CCP and take on at least some of the
characteristics of the fuel or the product, and other low-volume fossil fuel combustion
wastes. This ruling stated that uniquely associated wastes co-managed with large-volume
wastes fall under the Bevill exemption, but that uniquely associated wastes managed
separately are not exempt and can fall under RCRA subtitle D or C, if applicable (U.S.
EPA, 2000). Wastes that are not uniquely associated do not fall under this exemption.
Additionally, co-management of a hazardous waste with a Bevill waste will result in loss
of the Bevill exemption (U.S. EPA, 2000). Exempted wastes that are mixed with
50
hazardous wastes will not be exempt and will be subject to the RCRA Subtitle C mixture
rule. The mixture rule requires that a mixture of a listed hazardous waste and a
nonhazardous waste is always considered hazardous, unless the listed hazardous waste
was only listed because of a characteristic and the final mixture does not exhibit the
characteristic, in which case the mixture would not be hazardous, according to 40 CFR
261.
Future Regulatory Issues
Despite the extended period of study on CCPs employed for determining the final
regulation of May 2000, there is still much that is unknown about potential risks to
human or environmental health, if any, associated with using combustion waste in surface
impoundments or for mine filling. Because of these uncertainties and a continued public
interest in the issues surrounding CCPs, the U.S. EPA has continued to investigate
possible regulations of CCP disposal and use in mine filling and surface impoundments.
In August 2000, a coalition of environmental and health groups asked a Federal
court to review the U.S. EPA decision not to classify waste from fossil fuel combustion
as hazardous [Citizens Coal Council v. EPA, D.C. Cir. No. 00-1379]. The Clean Air
Task Force filed a petition with the U.S. Court of Appeals for the District of Columbia,
saying waste from utility and manufacturing companies contaminates water supplies and
kills fish. The coalition said the industries produce 115 million tons of waste each year,
70 percent of which goes into landfills, waste lagoons and coal mines.
By January 2001, upon consideration of motions to dismiss the August 2000
petition (separately filed by the U.S. EPA and the intervenors) the response of the
petitioners, and the replies by the U.S. EPA and the intervenors, the court ordered that the
motions to dismiss be granted. At the time, the Agency continued reviewing national-
51
and State-level guidance for the management and use of CCPs. The American Coal Ash
Association and other groups filed motions to intervene in the lawsuit; they were granted
intervenor status by the court.
At present, the regulatory focus has been centered on a series of meetings hosted by
the InterState Mining Compact Commission (IMCC) and U.S. EPA for State and Federal
government agencies interested in the upcoming U.S EPA rulemaking on placement of
coal combustion by-products at mine sites. These meetings have included a discussion of
U.S. EPA plans for rulemaking, OSM initiatives, research findings, and SMCRA
requirements, and a summary of State mining and solid waste regulatory program
requirements from about half of the States. Additionally, the U.S. EPA has entered into
the Coal Combustion Products Partnership (C2P2) with industry and CCP generators to
promote the beneficial use of CCPs and the potential environmental benefits from
beneficial use.
State Regulations on Fossil Fuel Combustion Products
On an individual basis, most states have adopted by reference or specific language
the federal determination of May 2000 that exempts CCPs from hazardous waste
regulations. Of the states that have not specifically adopted this convention, most
conditionally exempt these products from hazardous waste regulation, subject to testing
for hazardous characteristics or the pathway by which the material is disposed or
beneficially used. California is the only state in which CCPs are assumed hazardous
unless they satisfy testing requirements and do not exhibit hazardous waste characteristic.
In all of these cases, CCPs that are not classified as hazardous are regulated as solid
wastes. Similarly, states that exempt CCPs from hazardous waste regulation generally do
regulate these products as solid, industrial, industrial solid, or special wastes with
52
requirements for testing, treating, handling, storage, and disposal, and reuse of the
products, respective to their classification.
With some exception, most states do not have regulations that specifically
authorize the general use of CCPs in beneficial applications. However, the majority of
the states do have mechanisms in place, by which combustion product use is approved for
specifically defined applications, authorized on a case-by-case basis, or allowed under
umbrella recycling or generic waste reuse regulations. In some circumstances, these
general reuse regulations exempt CCPs from classification as solid wastes when they can
be reused or recycled as raw materials in an industrial process, as substitutes for
commercial products, or by being returned to their original generation process as a raw
material substitute. In some cases, the generic waste reuse regulations include other
industrial solid wastes, such as paper mill sludge and foundry sand.
Outside of formal regulations authorizing CCP reuse, the types of approved reuse
applications and the degree to which these applications are endorsed vary widely between
each state. Some states encourage broad use of fly ash, bottom ash, boiler slag, and FGD
sludge in numerous applications, while others limit these products’ reuse to specific,
controlled practices, like cement or concrete production. A review of each state’s
regulatory classification of CCPs and authorized beneficial uses is provided in Appendix
A. Based on this review, CCPs are most commonly used in the production of cement and
concrete, as structural fill, in construction or engineered structure projects, and in
highway construction and road paving. Beneficial uses that are allowed but present great
uncertainty and limited favor by state regulators include soil amendment, agricultural
applications, mine filling, and other types of land application.
53
CCP Regulatory Issues in the State of Florida
Mirroring the Federal history of CCP regulations, complete waste management
efforts began in Florida in 1976 with the Florida Resource Recovery and Management
Act, which established a Resource Recovery Council and subsequent policies that rapidly
developing counties must develop similar management plans. Chapter 62-701 (formerly
Chapter 17-701) of the Florida Administrative Code (FAC) deals primarily with waste
management and disposal issues, especially compliance to federal standards for landfill
requirements such as liners, covers, closure, and monitoring.
The comprehensive guidelines set forth in Chapter 62-701 FAC also recognized
that many industries would be affected by this rule and therefore set the following
allowance. These industries either had the option of abiding by the specific provisions of
the rule, with respect to landfills and waste management practices, or they may propose
other functionally equivalent practices, with complete documentation of the need and
equivalence. This exception applies to CCPs, as the electric utility industry has
traditionally requested alternate criteria for waste disposal facilities, with the stipulation
that such alternate criteria must provide information about and consideration of
•
chemical, biological, and physical waste characteristics,
•
predicted chemical speciation and movement in groundwater,
•
likelihood of exceeding groundwater standards in chemical discharge zones,
•
likelihood of release of methane or other gas,
•
waste management practices at the facility or industry as a whole,
•
leachate characterization,
•
discussion of cover requirements to limit odor, fire, dust, etc., and
•
discussion of closure requirements in the context of leachate generation.
54
Although the waste management and disposal regulations concerning CCPs have
been fully developed in Chapter 62-701 FAC, there is no comparable regulation in
Florida Statute that concerns the beneficial use of these products. Although some states
do authorize and expressly discuss CCP reuse in beneficial applications, there is great
discrepancy in both solid waste and beneficial use requirements on a state-by-state basis.
The similarities and differences between CCP regulatory status in each state is shown in
Appendix A.
CHAPTER 3
LIFE CYCLE ASSESSMENT OF COAL COMBUSTION PRODUCTS
Introduction
Due to its low cost and high availability in the United States, coal is expected to be
an essential fuel source for electricity production at fossil fuel powered electric utilities
for present and future generations (Beér, 2000). Coal is combusted at over 1,000
electricity generating units and accounts for almost 60% of the total fuel source used by
electric utilities (EIA, 2003). From an environmental perspective, coal utilization
presents a management challenge for utilities, as coal combustion processes generate
significant amounts of by-products at each stage during electricity generation. Of these
byproducts, this work is specifically focused on the generation, use, and disposal of high
volume solid wastes and byproducts, also termed coal combustion products (CCPs).
Almost 108 million metric tons of CCPs, specifically fly ash, bottom ash, boiler
slag, and flue gas desulfurization (FGD) material, are generated on an annual basis within
the United States (ACAA, 2003). Fly ash is the term generally used to describe the ash
and non-combustible minerals that are released from coal during combustion and that
“fly” up and out of the boiler with the flue gases (Halverson et al., 2001). Bottom ash
and boiler slag are the heavy, coarse, granular, incombustible particles remaining in the
bottom of coal-fired boilers (Stewart, 1997). FGD material is produced as the residue of
air emissions control devices designed to remove SO2 from the flue gas. These CCPs are
primarily composed of oxides of silicon, aluminum, iron, and calcium, in addition to
small amounts of magnesium, titanium, potassium, phosphorus, sulfur, and trace metals,
55
56
which were present in the source coal or added during processing stages (Gainer, 1996;
Iyer and Scott, 2001).
The physical and chemical characteristics of CCPs enable their use in almost every
engineering and manufacturing market in which other minerals have been traditionally
used. In fact, CCPs have become the third most abundant mineral resource in the U.S.
(Dienhart et al., 1998). It is estimated that approximately 34 million tons, or 28 percent,
of these high-volume CCPs generated in the United States are reused in a beneficial
application, including cement and concrete production, road pavement, soil amendments,
material recovery, and waste stabilization (ACAA, 2003). Beneficial use of CCPs has the
potential to minimize or eliminate the cost and problems of disposal; requires less area
for disposal, enabling other land uses and decreasing permit requirements; achieves
financial returns from product sales; replaces some scarce or expensive natural resources;
and conserves energy required for processing or transporting the products for disposal
(Joshi and Lohtia, 1997).
However, in the U.S., the remaining 72 percent of these products are still being
disposed in landfills or surface impoundments (ACAA, 2003). Both of these disposal
methods have the potential to create environmental impacts on human and environmental
health. Potential impacts from landfills include dust emissions, contaminant runoff with
stormwater, and leaching of trace metals into nearby water and soils. Landfills also
require large land areas and higher operating energy. Surface impoundments have
similar potential impacts as landfills, but the risk from contaminant leaching is higher
because the CCPs are handled and stored in a wet environment. However, this wet
57
environment also prevents the possibility of dust emissions. Surface impoundments also
require less space and less energy to operate than do landfills.
The environmental impacts associated with CCP disposal and beneficial use have
not been fully compared. Therefore, the objective of this work is to use life cycle
assessment to calculate the environmental impacts created during the life cycle of CCPs
and to compare management alternatives for these products, with the goal to minimize
impact on human health and environmental quality.
Method
LCA is a methodology for assessing the overall environmental impacts of a given
product or process throughout its entire life. This “cradle-to-grave” approach includes all
direct and indirect impacts generated, beginning with production of raw materials and
continuing to the waste phase of the product cycle (van den Broek et al., 2001). LCA is a
valuable tool, as it emphasizes a holistic focus on products, the functions they fulfill, and
the entirety of environmental impacts they create, rather than on individual processes or
impacts to specific environmental compartments (Hauschild and Wenzel, 2000).
This LCA was performed following guidelines of the ISO 14040 standard, which
calls for four phases: definition of goal and scope, inventory of material and energy
inputs and outputs throughout the life cycle, impact assessment to create an
environmental impact profile, and interpretation of the impact profile according to the
defined goal and scope. Calculations required for these phases were performed with
primary data (collected directly from Florida utilities) and secondary data (literature and
regulatory agency publications), using SimaPro 5.1, an LCA software program developed
by PRé Consultants. SimaPro 5.1 also contains inventory data for common products and
processes in databases created by ETH-ESU (Uster, Switzerland), Buwal 250 (Bern,
58
Switzerland), and Franklin Associates (Prairie Village, Kansas, USA), among others
(Goedkoop and Oele, 2001).
Scope and Goal Definition
The goal of this study is to determine the environmental impacts associated with
the life cycle of CCPs, considering a variety of CCP disposal and beneficial use
scenarios. The ultimate objective is to use this LCA to create a decision tool by which
regulators and CCP generators can manage combustion byproducts with minimal impact
to human and environmental health. Therefore, the LCA scope includes all aspects of the
CCP life cycle: raw material extraction and refining of coal, coal processing, coal use,
and CCP use and disposal. The scope is limited to CCP generation at electric utilities
within the State of Florida. Furthermore, this LCA specifically examines coal processing
and combustion technology that is well established and currently used.
To assess the CCP use stage of the LCA, it is assumed that the CCPs are recycled
in an open loop to an external life cycle. The external life cycle includes the beneficial
use application for which the CCPs are designated. The CCPs are thus considered
exported functions that replace virgin raw materials in the beneficial use application, a
classification that is appropriate since the CCPs have similar characteristics and
performance as the materials that they replace (Ekvall and Finnveden, 2001). Therefore,
the scope of this LCA is expanded to include the upstream processes (material extraction,
refinement, and processing) for the materials replaced by CCPs in beneficial use
applications. However, the use, recycling, and disposal stages of any products generated
from the beneficial use application are not considered here, as it is assumed that these
would be unchanged by use of CCPs instead of other raw materials. For example, if fly
ash is used as a replacement for Portland cement in concrete block production, this LCA
59
would include comparative stages of fly ash and Portland cement, including raw material
extraction, refining, and processing, but will not include the use, recycling, and disposal
of the concrete block produced. This assumption somewhat limits the LCA results and
impact assessment, as it neglects any impacts that could be created by use of CCPs over a
long period of time, e.g., the re-evolution of trace elements originating from the fly ash
into ecosystems in which the beneficial use product is used. However, this assumption is
necessitated by a lack of research and available data regarding long-term and universal
spatial- and temporal- performance and environmental impacts of products made with
CCPs.
Functional unit
A functional unit is used in LCA to homogenize all inputs, outputs, and impacts
with respect to a common product, service, or equivalent value, with the goal of creating
fair comparisons between very different products or services. In this LCA, the functional
unit was chosen to be one ton of coal combusted. Although many LCAs that analyze
energy production have used kWhr generated as the functional unit for comparison, there
are two primary reasons for choosing to normalize data and results based on tons coal
combusted (Gagnon et al., 2002). First, the values that report the inputs, outputs, and
impacts for this system are almost exclusively reported in mass units, which leads to the
conclusion that a functional unit given likewise in mass units will produce clarity and
comparability in the LCA results. Moreover, the CCPs assessed here are direct products
of the ash and sulfur contents in the source coal, such that their environmental impact and
marketable value is tied directly to the coal that is combusted, rather than the energy
generated. Following ISO 14040 procedures, it is recommended that the functional unit
be defined as close as possible to the end use of the product considered (Guinée et al.,
60
2002). However, using a mass-based functional unit does not exclude comparison by
kWhr generated or units specific to a given power plant or region of interest. The amount
of coal combusted in a generating system can be related to electricity generated if the
coal’s heating value and the power plant’s efficiency and operating capacity are known.
System description and boundaries
The system in consideration was developed to represent typical processes at
pulverized coal-fired power generation sites in Florida, although these processes are
relatively common to power plants across the U.S. (Spath et al., 1999). This system can
be represented by the traditional levels of an LCA model, in which the overall system is
described as Level 1 and then subdivided in Level 2 sublayers, as shown in Figure 3-1.
The Level 2 sublayers are also broken down into Level 3 unit processes, as shown in
Figure 3-2.
Level 1
Coal Combustion Products LCA
Coal
Chemicals and
other Materials
Water
Energy
Level 2
Raw Material Extraction and Preparation
Level 2.1
Material Processing
Level 2.2
Electricity
Byproducts
Waste Heat
Emissions to Air
Fuel
Coal Combustion Product Beneficial Use
Level 2.3
Emissions to Water
Land
Equipment
Coal Combustion Product Disposal
Level 2.4
Figure 3-1: Level 1 and 2 diagram for an LCA of CCPs
Emissions to Land
61
Level 2.1
Raw Material Extraction and Preparation
Level 2.1.1
Underground
and surface
coal mining
Level 2.1.2
Transportation
of coal to
preparation
Level 2.1.3
Coal
preparation
Level 2.1.4
Transportation
of coal to
utility
Level 2.2.3
Primary air
emissions
control
Level 2.2.4
Flue gas
desulfurization
Level 2.2
Material Processing
Level 2.2.1
Coal storage
and handling
Level 2.2.2
Coal
combustion for
electric power
Level 2.3
Coal Combustion Product Beneficial Use
Level 2.3.1
CCP storage
and handling
Level 2.3.2
Beneficiation,
if required
Level 2.3.3
CCP
transportation
to end use
Level 2.3.4
Beneficial use
by material
replacement
Level 2.4
Coal Combustion Product Disposal
Level 2.4.1
CCP storage
and handling
Level 2.4.2
CCP treatment
or fixation
Level 2.4.3
CCP landfill or
long-term
storage
Level 2.4.4
CCP
impoundment
Figure 3-2: Level 3 diagram for an LCA of CCPs
As can be seen in Figure 3-1, the Level 1 diagram shows the generic inputs,
outputs, and emissions from the system over its entire life cycle. The Level 2 flow chart
breaks the systems into four stages: raw material extraction and preparation, material
processing, CCP beneficial use, and CCP disposal. Included in these stages are the
processes of coal mining, cleaning, and transportation to the utility, coal combustion to
62
produce electricity, flue gas cleaning with electrostatic precipitators and flue gas
desulfurization units, and disposal and beneficial use of coal combustion products.
For each of the life cycle stages shown in Figure 3-2, boundaries are set to include
extraction and refinement of natural resources, production of required materials and
chemicals, transportation, construction of necessary capital goods and infrastructure (e.g.,
roads, equipment, vehicles, buildings, etc.), energy consumption, and all emissions to air,
water, and land.
The life cycle stages considered have variables that change on a site-by-site basis.
However, many of these variables have been aggregated to streamline the LCA process to
focus on representative operations at Florida utilities. Some of the major assumptions
and system characteristics used are discussed here. Unless stated otherwise, the variables
given here were obtained from site visits to four Florida utilities, interviews with
environmental managers at these utilities, and surveys administered to coal-fired utilities
in the state.
Coal mining and preparation. Mined coal originates from two broad classes of
extractive processes: underground mining and surface mining. At present, about 60% of
all coal is produced from surface mines and the remaining 40% from underground mines;
and, therefore, this distribution is used for the LCA (Chircop, 1999). According to data
collected at Florida utilities, most coal-fired plants in Florida obtain their primary coal
from the Illinois Basin and other coal seams in the Interior Region, including Kentucky
and West Virginia; although spot coal sources include Colombia, Venezuela, South
Africa, and Australia. Bituminous, high volatile group C coal is predominantly used in
Florida. An average as-received ultimate analysis of this coal type is given in Table 3-1.
63
Table 3-1: Average ultimate analysis of coal on an as-received basis at Florida utilities
Characteristic
Weight Percent
Moisture content
9.77
Carbon content
70.46
Ash content
7.82
Sulfur content
1.35
Hydrogen content
4.59
Chlorine content
0.08
Oxygen content
5.92
Calorific value (BTU/lb)
12,356 BTU/lb
It is common practice that the run-of-mine coal be cleaned before transport to the
utility. This is generally performed at a facility located near the mine; therefore, it was
assumed that the coal must be transported on average of 25 miles by truck from the mine
mouth to the cleaning and preparation facility. The cleaning process is designed to
remove impurities from the coal, namely sulfur and ash, and to normalize the size
distribution by eliminating fines and very large pieces. Wet cleaning and separation
processes are generally preferred over dry processes to minimize fugitive dust emissions;
of these wet cleaning processes, jig washing has traditionally been the most common
method (Grayson, 1979; Wheelock and Markuszewski, 1984). Jig washing involves
subjecting the coal to alternating water currents across an inclined screen such that the
coal particles stratify and the clean, low specific gravity material passes to the surface
where it is collected and removed (Berkowitz, 1979). In this LCA, it is assumed that all
coal directed to the utilities is prepared by a simple wet cleaning process, modeled after
jig washing.
This system also included transportation of the coal from the site of preparation to
the utility. Coal is transported to Florida by freight train, barge, and truck, or in a
combination of some or all of these methods. Overall, the U.S. average for these three
64
modes of transportation breaks down as 73 percent by freight train, 15 percent by barge,
and 12 percent by truck (Chicorp, 1999).
Coal combustion and CCP generation. Once delivered to the utility, coal is
stored on an open pile with enough stockpiled for 30-45 days of operation. On average,
coal-fired utilities in Florida use between 550,000 and 8 million tons of coal on an annual
basis, depending on their generating capacity and their use of other fuel sources. Before
combustion, the coal is crushed, dried, and pulverized to 70% through a 200-mesh. To
simulate coal combustion in this LCA model, the system included wall- and tangentiallyfired dry and wet bottom boilers, with an average generating capacity of 2.44 MWhr per
ton of coal combusted.
Combustion emissions in the boiler exhaust gas are controlled by electrostatic
precipitators (ESPs) and flue gas desulfurization (FGD) systems. Of the utilities queried
in Florida, only two currently use an FGD system, but this sulfur dioxide control device
was included in the model to ensure that FGD residue would be considered with the other
CCPs. In addition, given the more stringent air pollution regulations and construction of
additional coal-fired generating facilities, it can be expected that the use of SO2 control
systems will increase in the future. The FGD system considered uses a limestone sorbent
and forced oxidation to produce byproduct gypsum, a marketable CCP.
CCP beneficial use. The system created for this LCA uses the base-case scenario
that 50 percent of the CCPs generated will be used in a beneficial application as a
replacement for virgin raw material. This percentage is higher than the national average
according to the American Coal Ash Association (ACAA), but it is representative of
average Florida CCP use. Although this percentage can vary between 0 and 100 in
65
Florida, 50 percent is the average rate at which CCPs are used. The beneficial uses
considered are those that are reported by the ACAA to be most often used with each of
the large-volume CCPs and that have the highest industry and regulatory acceptance.
These beneficial uses are detailed below in Table 3-2, along with percentages of the
relative amount of the given CCP designated for each beneficial use.
Table 3-2: Beneficial uses considered for each large-volume CCP
Fly Ash and Bottom Ash
Boiler Slag
FGD Material
Beneficial Use
Percentage
Beneficial Use
Percentage
Beneficial Use
Percentage
Cement and concrete
production
70%
Roofing granules and
blasting grit
98%
Gypsum and
wallboard
90%
Structural fill
20%
Structural fill
1%
Soil amendment
8%
Road base and
subbase
10%
Mineral filler
1%
Cement and concrete
production
2%
The base-case assessment of CCP beneficial uses also included transportation of
the materials by 28-ton truck over a distance of 50 miles to the end user. This distance
can be varied for comparison of scenarios with different distances from point of CCP
generation, but 50 miles is a reasonable and demonstrated base distance. Most utilities
have to subsidize some or all of the cost to transport CCPs for beneficial use, and,
therefore, it is desirable on their part that the transportation distance be minimized. No
beneficiation on the CCPs was considered in this system.
CCP disposal. The remaining 50 percent of all high volume CCPs not designated
for beneficial use is disposed of in either an onsite landfill or surface impoundment. Both
methods are common in Florida, as landfilling has the potential to store very large
quantities of CCPs for a long period, while impoundments are very inexpensive to
construct and operate (Woodward-Clyde, 1994). This assessment considers that half of
all CCPs disposed are sent to a landfill and half to a surface impoundment. Neither of
66
these disposal methods includes liners in the system evaluated, although using synthetic
or CCP-derived liners is a growing practice nationally and in Florida. However, most
available data only existed for systems with no liner, and the system model was
constrained by data availability.
Inventory Analysis
The inventory analysis was performed to compile the inputs, outputs, and
environmental exchanges resulting from each of the four Level 2 stages in the LCA
(Figures 3-1 and 3-2). This analysis includes data collection, verification of data quality,
addressing data limitations, and allocation.
Data collection
Data for each of the LCA processes was collected from literature, personal
interviews and site visits at four Florida utilities, surveys administered to CCP marketers
and environmental managers at utilities, and monitoring and compliance data collected by
or reported to the U.S. EPA. U.S. EPA data included hourly emissions data from electric
utilities obtained through the Acid Rain/Ozone Transport Commission and Toxics
Release Inventory (TRI) data reported for the four utilities that were visited as part of this
project (U.S. EPA, 2003a, U.S. EPA, 2003b). The surveys and questionnaires used in
data collection are shown in Appendix B. Results of these data collection efforts are
compiled in Appendix C.
When data from these sources were not available or suitable, they were obtained
from the databases and process blocks in SimaPro 5.1 that were created by ETH-ESU
(Uster, Switzerland) and Franklin Associates (Prairie Village, Kansas, USA) (Goedkoop
and Oele, 2001). Data that were only obtained from SimaPro databases are classified in
the production blocks given below in Table 3-3.
67
Table 3-3: Process block data obtained from SimaPro databases
Process Block
Coal production by underground and surface mining
Disposal of coal tailings and mining wastes
Diesel and fuel oil production
U.S. average electricity production
Aluminum production from ore and recycled aluminum
Steel production from ore and recycled steel
Iron production from ore and recycled iron
Lime production
Limestone production
Other chemical production
Alternative material production for CCP beneficial use[1]
Infrastructure for coal mining and preparation
Infrastructure for road and rail transportation
Transportation by road and rail
Infrastructure for barge transportation
Transportation by barge
Infrastructure for power plant and ancillary operations
Database
ETH-ESU
ETH-ESU
ETH-ESU
Franklin Associates
ETH-ESU
ETH-ESU
ETH-ESU
ETH-ESU
ETH-ESU
ETH-ESU
ETH-ESU
ETH-ESU
ETH-ESU
ETH-ESU
Franklin Associates
Franklin Associates
ETH-ESU
[1] These materials include Portland cement, paving concrete, structural fill,
phosphogypsum, lime-based fertilizer, glass, sand, and gravel
Data quality
Because a significant portion of data used to create this LCA was obtained from
external databases provided by SimaPro and a wide variety of literature and industry
values, data quality requirements were established to ensure the most valid and accurate
data were being used. Primary requirements for data inclusion were based on temporal
relevance, process specificity, geographic proximity, and technological application
(Goedkoop and Oele, 2001). As the most recent data for the most widely used and
accepted technology are desired, it was decided that data would be used only if they were
from 1990 to present for processes using average, modern, or best available technology
(Hauschild and Wenzel, 2000). Furthermore, data from North America and specifically
the U.S. were preferred to give geographic relevance to the results; although data from
68
Europe were also included, based on their high availability and applicability. Finally,
data were selected to represent the processes modeled in this LCA with a high level of
specificity, that is, they were obtained from a specific process represented in the LCA or
from an average of all outputs from processes with the same function.
Data limitations
Despite efforts to ensure the use of high quality data, it is inevitable that
uncertainties and limitations exist that restrict a generalized interpretation of LCA results.
Foremost, obtaining data from multiple types of sources adds uncertainty as to the data’s
accuracy and reproducibility in the system considered here. In addition, using data that
are specific to Florida utility operations places a severe geographic limitation on the
widespread use of the LCA results and conclusions. However, the technology and
operational practices modeled in this LCA for coal combustion and CCP management are
relatively common across the electric utility industry in the U.S. (Spath et al., 1999). In
addition, sensitivity analysis was performed to determine the viability of the data and to
ensure that the trends illustrated in the LCA results can be used for comparative
assessment and decision making regarding CCP management. Model validation was
performed using data obtained from surveying utilities in the southeast that were not
included in the original data set.
Allocation
In addressing data limitations, allocation of impacts across the process system must
be considered and avoided if possible. The system considered in this LCA has the
primary objective of producing electricity to meet the energy demand from residential,
commercial, industrial, and transportation sectors in the U.S., and specifically, the Florida
economy. However, as discussed before, significant amounts of byproducts and waste
69
are also generated during the electricity generation process, creating the need to address
allocation of impacts in the LCA. Allocation is required to identify joint processes in a
product system and to determine how to distribute aggregated environmental emissions
and impacts from these joint processes to the resulting products (Hauschild and Wenzel,
2000).
In the LCA of CCPs, the first allocation challenge is in apportioning impacts from
coal combustion between electricity generation and CCP generation. This challenge was
addressed by first classifying the CCPs as waste products from a system that is ultimately
designed and optimized for electricity generation. Next, the system was expanded to
include the downstream management of CCPs by disposal or beneficial use. Finally, the
disposal and beneficial use of CCPs are subdivided into processes specific to each of the
CCPs generated. The subdivision method is suitable here, as each of the disposal
processes has a single function and individual available environmental data (Ekvall and
Finnveden, 2001). The CCPs cannot, however, be excluded all together from sharing in
the impacts from coal combustion, as they do possess utilization value as raw materials to
outside processes (Vigon et al., 1994). In the case of CCPs that are exported from this
life cycle into an external life cycle of beneficial use applications, allocation has been
largely avoided by expanding the boundaries of the system to include the additional
functionality of CCPs and the alternative production of the materials they replace
(Hauschild and Wenzen, 2000).
Impact Assessment
Impact assessment was performed to relate the inventory results to potential effects
the process system can have on human health, ecosystem health, and natural resources.
For this LCA, three published impact assessment methods were used to compare and
70
contrast results. These methods were Eco-Indicator 99(I), Environmental Design of
Industrial Products (EDIP), and Centre of Environmental Science (CML) from Leiden
University (Goedkoop and Spriensma, 2001). Within these methods, impact categories
used were selected based on their consistency with traditional categories, such as global
warming, acidification, ozone depletion, and resource consumption (Barnthouse et al.,
1998). Additionally, some impact categories were also used to calculate environmental
impacts specific to this LCA system, such as carcinogens, respiratory inorganics, smog
formation, ecotoxicity, and land use, although these vary by the method used. Categories
used in each of the three impact assessments are given in Table 3-4.
Table 3-4: Impact categories and units for each impact assessment method used
Eco-indicator 99(I)
Category
Unit
Climate change DALY
CML
EDIP
Category
Unit
Global warming (GWP100) kg CO2 eq
Ozone layer
DALY
Ozone depletion (ODP)
Acidification/
Eutrophication PDF*m2yr Acidification
Unit
Global warming (GWP 100) g CO2 eq
kg CFC-11 eq Ozone depletion
g CFC-11 eq
kg SO2 eq
Acidification
g SO2 eq
Eutrophication
g NO3 eq
Photochemical smog
g C2H2 eq
PO---4
Radiation
DALY
Eutrophication
kg
Carcinogens
DALY
Photochemical oxidation
kg C2H2
Ecotoxicity
PDF*m2yr Human toxicity
Resp. organics
DALY
Resp. inorganics DALY
Category
eq
kg 1,4-DB eq Ecotoxicity water chronic
m3/g
Fresh water aquatic ecotox. kg 1,4-DB eq Ecotoxicity water acute
m3/g
Marine aquatic ecotoxicity kg 1,4-DB eq Human toxicity air
m3/g
Land use
PDF*m2yr Terrestrial ecotoxicity
kg 1,4-DB eq Human toxicity water
m3/g
Minerals
MJ surplus Abiotic depletion
kg Sb eq
m3/g
Human toxicity soil
Units used: DALY= disability adjusted life years; PDF*m2yr= potentially disappearing fraction of species per square meter per
year; MJ surplus= energy (MJ) required to compensate lower future ore grade; kg(g) CO2 eq= mass carbon dioxide equivalent;
kg(g) CFC-11 eq= mass of CFC-11 equivalent; kg(g) SO2 eq = mass sulfur dioxide equivalent; kg(g) PO4--- eq= mass
phosphate equivalent; kg(g) C2H2 eq= mass ethene equivalent; kg(g) 1,4-DB eq= mass 1,4-dichlorobenzene equivalent; kg(g)
Sb eq= mass antimony equivalent; kg(g) NO3 eq= mass nitrate equivalent; m3/g= exposure effect to a given compartment per
mass of chemical emitted
Impact factors in each of these categories were predefined by the three methods for
each of the emissions that are reported in the inventory phase. These factors were used to
calculate impact characterization values by first multiplying the factors with their
71
respective emission, and then summing the products of all multiplication in a specific
category to obtain a total numeric value for the impact category. In other words, given an
emission of substance i that has a magnitude Qi and an impact factor EFj for the j impact
category, the emission’s potential contribution to the impact category would be expressed
EP(j)i = Qi * EF(j)i,
(1)
and the total category characterization value for all emissions would be
EP(j) = ΣEP(j)i (Hauschild and Wenzel, 2000).
(2)
Characterization values were calculated for all impact categories in each of the
three methods used. These characterized impacts were also normalized by expressing
them with respect to the total impacts of each category within a reference geographic
region and representative time period. Normalization was used to provide a measure of
the relative importance of impacts from a given process in comparison to the total
impacts on a regional or global basis (Huijbregts et al., 2003). Normalization was the
extent to which impact assessment was performed, as weighting was not included in the
analysis. Weighting, or valuation, is a highly subjective evaluation method by which the
LCA results are weighted, ranked, or aggregated to derive a final score for a process or
product (Barnthouse et al., 1998). In this LCA, the results will be used by a variety of
stakeholders, including academia, electric utility industry, and regulators, whose interests
were best served by presenting unweighted results and allowing each party to draw
conclusions based on their established priorities.
72
Results and Discussion
LCA Scope
The scope of the LCA was to consider average operations at Florida utilities.
Findings on general utility operation and CCP generation use were compiled, as shown in
Table 3-5 Electricity production, coal use, and CCP generation and beneficial use vary
widely across the utilities surveyed. These differences are attributed to different
combustion systems, air emissions control devices, and fuel sources.
Table 3-5: Summary of four Florida utilities used for LCA system modeling
Site
Power
Station
Location
1 Crist
Pensacola
2 Big Bend
Tampa
3 McIntosh
Lakeland
4 Crystal River Crystal River
Net
Percent
Generation
Coal Use
CCP Production Beneficial Use
(MW)
(tons per year) (tons per year)
(%)
980
2,000,000
160,000
74%
1,125
3,219,672
1,185,461
99%
340
900,857
253,994
0%
2,430
7,296,000
555,000
90%
Inventory Results
The life cycle inventory (LCI) was calculated for raw material inputs and emissions
to air, water, and land. The LCI results reported herein are based on one ton coal
combusted and are partitioned by the life cycle stage from which they originated: coal
mining and extraction, coal combustion, CCP beneficial use, and CCP disposal. There
were almost 500 total inputs and outputs for the system considered. However, items
accounting for less than 0.1% by weight were excluded from the final inventory results.
The entire inventory results are compiled in Appendix D.
The highest 99.9% of inputs from raw material and outputs into environmental
compartments are shown below in Tables 3-6 through 3-9. Each value is expressed by
mass emitted per ton of coal combusted and by its percentage contribution to the total
input from each of the four life cycle stages. Negative values, generally appearing only
73
in the beneficial use columns, indicate that the input or output of a given material is
prevented from occurring by use of CCPs rather than virgin raw materials in a beneficial
use application. A discussion of the relative contributions by inputs and outputs to the
total inventory is given after each table is presented.
Table 3-6: Inventory of raw material inputs for each life cycle stage
Substance
Coal Mining and
Coal
Preparation
% of total from Combustion
(kg)
mining/prep
(kg)
% of total
from coal
combustion
CCP
% of total
Beneficial Use from beneficial CCP Disposal
(kg)
use
(kg)
% of total
from
disposal
Total
(kg)
water
3.91E+03
58.9%
2.54E+03
38.3%
-5.11E+01
-0.8%
2.37E+02
3.6%
6.64E+03
coal
1.81E+03
99.9%
1.37E+01
0.8%
-1.25E+01
-0.7%
3.62E-01
0.0%
1.81E+03
natural gas
9.73E+02
99.7%
2.10E+00
0.2%
-1.10E-01
0.0%
9.80E-01
0.1%
9.76E+02
limestone
7.58E+00
5.5%
2.05E+02
149.7%
-7.59E+01
-55.5%
4.13E-01
0.3%
1.37E+02
gravel
8.41E+01
73.9%
2.85E+00
2.5%
-1.42E+01
-12.5%
4.11E+01
36.1%
1.14E+02
crude oil
2.94E+01
99.0%
7.69E-01
2.6%
-1.24E+00
-4.2%
7.79E-01
2.6%
2.97E+01
petroleum gas
1.86E+01
99.9%
3.53E-02
0.2%
-8.63E-02
-0.5%
6.94E-02
0.4%
1.86E+01
iron (in ore)
8.91E+00
90.9%
7.17E-01
7.3%
2.08E-03
0.0%
1.75E-01
1.8%
9.80E+00
wood
8.57E+00
99.8%
7.65E-02
0.9%
-6.06E-02
-0.7%
3.79E-03
0.0%
8.59E+00
methane
4.46E+00
100.6%
2.85E-02
0.6%
-5.57E-02
-1.3%
1.68E-03
0.0%
4.43E+00
Water, coal, and natural gas are the chief inputs from raw material, and their
contribution to total raw material use is primarily seen in the stage of coal mining and
preparation. While coal requirements are obvious for the system being considered, water
use and natural gas use are not completely intuitive. Water use is derived from coal
cleaning, dust control, and coal mine waste management. Natural gas is used in a wide
variety of processes, including the production of infrastructure and equipment used in
extraction and refining, generation of electricity according to the U.S. average, and the
production of chemicals used for dust control. The high contribution of limestone to the
total raw material inputs is accounted by its use as an FGD sorbent at the electric utility.
Gravel, crude oil, iron, and wood are all primarily used for construction of infrastructure
and equipment used for coal mining, refining, and transportation. Methane is considered
74
an input from nature, as it is formed in coal seams concurrent to coal formation and is
only shown in significant amounts during the mining and preparation life cycle stage.
Table 3-7: Inventory of emissions to air from each life cycle stage
Substance
Coal Mining and % of total
Preparation
from
(kg)
mining/prep
Coal
Combustion
(kg)
% of total CCP Beneficial
from coal
Use
combustion
(kg)
% of total
from
beneficial
use
CCP
Disposal
(kg)
% of total
from
disposal
Total
(kg)
CO2
2.89E+02
25.6%
9.12E+02
80.9%
-7.71E+01
-6.8%
2.78E+00
0.2%
1.13E+03
NMVOC
6.84E+00
99.6%
4.28E-02
0.6%
-2.79E-02
-0.4%
1.50E-02
0.2%
6.86E+00
CH4
6.28E+00
111.2%
1.00E-01
1.8%
-7.41E-01
-13.1%
7.60E-03
0.1%
5.65E+00
SOx
1.20E+00
26.3%
3.55E+00
78.0%
-2.07E-01
-4.6%
9.44E-03
0.2%
4.55E+00
NOx
2.08E+00
54.5%
1.92E+00
50.2%
-2.00E-01
-5.2%
1.86E-02
0.5%
3.81E+00
7.92E-01
33.0%
7.07E-01
29.5%
-1.55E-01
-6.5%
1.05E+00
43.9%
2.40E+00
CO
7.46E-01
87.9%
1.80E-01
21.2%
-8.74E-02
-10.3%
9.73E-03
1.1%
8.48E-01
HCl
9.19E-03
1.1%
8.24E-01
99.0%
-1.01E-03
-0.1%
4.33E-05
0.0%
8.32E-01
Particulate
matter
(PM10)
Emissions to air are produced primarily during the stages of coal mining and
preparation and coal combustion. As might be expected, CO2, the major air emission
from combustion systems, comprises over 98% of the total outputs to air. SOx emissions
are also generated in the highest amounts during coal combustion. Particulate matter
(PM10) and NOx emissions are distributed between extraction and combustion stages.
Mining and preparation includes the transportation of coal from mining to preparation
plants to the utility by rail, road, and barge, thus accounting for output of PM10, NOx,
non-methane volatile organic compounds (NMVOCs), and CO from the incomplete
combustion of diesel and petroleum fuels by transport equipment. It is likely that
NMVOC emissions during coal combustion are higher than reported here, but these are
difficult to quantify, as utilities generally do not monitor or regularly perform mass
balances on these compounds. HCl is generated almost exclusively from combustion,
because of the chlorine content in the source coal used. Methane is emitted from
underground coal mining and, to a lesser extent, surface mining, when the coal seam is
opened and trapped methane is released to the atmosphere with limited control devices in
75
place. Percentages greater than 100 shown for methane or other compounds are obtained
when the compound has a negative inventory value in another life cycle stage, i.e., its
emission is being prevented by use of CCPs instead of virgin raw materials in beneficial
use applications.
Table 3-8: Inventory of emissions to water from each life cycle stage
Substance
Coal
CCP
% of total
Mining and % of total
Coal
% of total Beneficial
from
CCP
% of total
Preparation
from
Combustion from coal
Use
beneficial Disposal
from
(kg)
mining/prep
(kg)
combustion
(kg)
use
(kg)
disposal
Total
(kg)
Cl-
1.43E+01
96.6%
7.98E-02
0.5%
-1.14E-01
-0.8%
5.40E-01
3.6% 1.48E+01
Sulphates
1.28E+01
98.2%
1.48E-01
1.1%
-6.76E-02
-0.5%
1.57E-01
1.2% 1.30E+01
dissolved solids
1.73E+00
18.0%
8.80E-02
0.9%
-5.58E-02
-0.6% 7.85E+00
81.6% 9.62E+00
Na
5.94E+00
99.5%
2.23E-02
0.4%
-3.47E-02
-0.6%
4.05E-02
Al
3.01E+00
100.2%
7.20E-03
0.2%
-1.47E-02
-0.5%
2.68E-03
0.1% 3.01E+00
Ca
2.26E+00
91.4%
4.65E-02
1.9%
-1.33E-02
-0.5%
1.80E-01
7.3% 2.47E+00
Mg
2.41E+00
100.2%
5.82E-03
0.2%
-1.19E-02
-0.5%
2.15E-03
0.1% 2.41E+00
K
9.47E-01
99.5%
2.38E-03
0.2%
-4.93E-03
-0.5%
7.64E-03
0.8%
9.52E-01
Fe
9.11E-01
98.6%
3.69E-03
0.4%
-4.89E-03
-0.5%
1.39E-02
1.5%
9.24E-01
0.7% 5.97E+00
Ba
2.68E-01
95.5%
6.84E-04
0.2%
-1.44E-03
-0.5%
1.34E-02
4.8%
2.81E-01
TOC
2.35E-01
95.6%
3.12E-03
1.3%
4.77E-03
1.9%
2.98E-03
1.2%
2.46E-01
phosphate
1.81E-01
94.5%
1.15E-02
6.0%
-9.25E-04
-0.5%
2.51E-05
0.0%
1.92E-01
Ti
1.81E-01
100.0%
4.33E-04
0.2%
-8.81E-04
-0.5%
4.88E-04
0.3%
1.81E-01
suspended solids
1.69E-01
70.7%
7.94E-02
33.1%
-1.42E-02
-5.9%
4.90E-03
2.0%
2.40E-01
B
4.03E-03
4.2%
8.89E-02
92.7%
-3.14E-04
-0.3%
3.33E-03
3.5%
9.59E-02
Sr
7.43E-02
99.6%
2.82E-04
0.4%
-6.87E-04
-0.9%
6.99E-04
0.9%
7.46E-02
Mn
6.47E-02
98.7%
8.70E-04
1.3%
-5.65E-04
-0.9%
5.76E-04
0.9%
6.56E-02
fats/oils
8.64E-02
99.3%
1.12E-03
1.3%
-2.55E-03
-2.9%
2.02E-03
2.3%
8.70E-02
baryte
2.47E-02
98.4%
1.44E-03
5.7%
-2.53E-03
-10.1%
1.48E-03
5.9%
2.51E-02
Pb
1.52E-02
90.5%
3.17E-04
1.9%
-7.32E-05
-0.4%
1.35E-03
8.0%
1.68E-02
Emissions to water are more widely distributed from multiple emissions than
outputs to other environmental compartments. The major emissions to water are Cl ions
and sulphates that are released during coal mining and refining processes. A significant
amount of metals, minerals, and other suspended solids are also emitted with coal tailings
and other mining waste during coal extraction and preparation. Emissions to water
during coal combustion primarily result from process water discharges, including coal
pile runoff, boiler blowdown, cooling tower blowdown and sludge, water treatment
76
sludge, air heater wash water, boiler chemical cleaning wastes, floor and yard drains and
sumps, laboratory wastes, and wastewater treatment sludge.
Table 3-9: Inventory of emissions to soil from each life cycle stage
Substance
Coal Mining
and
% of total
Coal
% of total
Preparation
from coal Combustion
from
(kg)
combustion
(kg)
mining/prep
CCP
Beneficial
Use
(kg)
% of total
from
beneficial
use
CCP
Disposal
(kg)
% of total
from
disposal
Total
(kg)
Ba
1.57E-02
0.4%
1.95E-02
0.4%
-2.38E-04
0.0%
4.32E+00
99.2%
4.35E+00
Cu
9.58E-03
0.4%
1.19E-02
0.4%
-1.46E-04
0.0%
2.64E+00
99.2%
2.66E+00
Mn
3.08E-03
0.4%
3.83E-03
0.4%
-4.85E-05
0.0%
8.50E-01
99.2%
8.57E-01
Zn
3.35E-03
0.4%
2.69E-03
0.4%
-4.17E-05
0.0%
7.43E-01
99.2%
7.49E-01
Cr
1.66E-03
0.4%
2.07E-03
0.4%
-2.54E-05
0.0%
4.58E-01
99.2%
4.62E-01
Ni
1.14E-03
0.4%
1.42E-03
0.4%
-1.73E-05
0.0%
3.14E-01
99.2%
3.17E-01
As
1.08E-03
0.4%
1.35E-03
0.4%
-1.65E-05
0.0%
2.99E-01
99.2%
3.01E-01
Pb
8.97E-04
0.4%
1.12E-03
0.4%
-1.37E-05
0.0%
2.47E-01
99.2%
2.49E-01
V
5.14E-04
0.4%
6.40E-04
0.4%
-7.82E-06
0.0%
1.42E-01
99.2%
1.43E-01
Co
1.37E-04
0.4%
1.70E-04
0.4%
-2.08E-06
0.0%
3.77E-02
99.2%
3.80E-02
Hg
1.17E-05
0.4%
1.46E-05
0.4%
-1.78E-07
0.0%
3.24E-03
99.2%
3.27E-03
Mo
7.54E-06
0.4%
9.39E-06
0.4%
-1.15E-07
0.0%
2.08E-03
99.2%
2.10E-03
Oil
1.54E-03
98.8%
4.03E-05
2.6%
-9.49E-05
-6.1%
7.37E-05
4.7%
1.56E-03
Emissions to soil are relatively small in magnitude, but are composed of trace
metals and other compounds that can pose a significant risk to human and environmental
health. These emissions almost exclusively originate from surface impoundments and
landfills used for CCP disposal, where these compounds can leach into the soil and
subsurface surrounding an unlined disposal site. Again, the life cycle system examined
here included only unlined disposal facilities such that these emissions represent a basecase or worst-case scenario.
Impact Assessment Results
Because impacts were calculated and analyzed with three different impact
assessment methods and three sets of impact categories, some of the results presented
here cannot be compared directly to each other. However, general trends and impact
areas can be demonstrated from these findings.
77
Impact characterization
Each of the impact assessment methods was used to characterize the life cycle
impacts into categories that were previously defined in Table 3-4. The results of this
characterization are shown below in Figures 3-3 through 3-5. In each of these figures,
the bars represent relative percent contribution by each life cycle stage to the total impact
for each of the impact categories.
80%
60%
40%
20%
0%
Coal Mining and Preparation
Coal Combustion
CCP Beneficial Use
Minerals
Land use
Resp. inorganics
Impact Category
Resp. organics
Ecotoxicity
Carcinogens
Radiation
Acidification/
Eutrophication
Ozone layer
-20%
Climate change
% Contribution by life-cycle stage to total
category impact
100%
CCP Disposal
Figure 3-3: Eco-indicator 99 impact characterization
According to the Eco-indicator 99 method, coal mining and preparation is
responsible for a majority of the impacts to respiratory organics, radiation, ozone layer
depletion, and mineral use. Coal combustion is the primary contributor to respiratory
78
inorganics, climate change, and acidification and eutrophication. The disposal of CCPs
in landfills or surface impoundments is responsible for the major impacts by carcinogen
release, ecotoxicity, and land use. On the other hand, CCP beneficial use shows a
negative impact in many of the impact categories, including respiratory inorganics,
respiratory organics, climate change, radiation, and acidification and eutrophication. A
negative value indicates the impact was prevented from occurring by use of the CCPs
% Contribution by life-cycle stage to total
category impact
instead of virgin raw materials.
Coal Mining and Preparation
Abiotic depletion
Terrestrial ecotoxicity
Marine aquatic ecotoxicity
Fresh water aquatic ecotox.
Human toxicity
Photochemical oxidation
Eutrophication
Acidification
Ozone depletion (ODP)
Global warming (GWP100)
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Impact category
Coal Combustion
CCP Beneficial Use
CCP Disposal
Figure 3-4: CML impact characterization
The CML method produces similar results, with coal mining and preparation
responsible for the major impacts to ozone depletion and abiotic resource depletion. This
method separated eutrophication from acidification, and the results indicate that these
79
categories are impacted primarily by coal mining and combustion, respectively.
Additionally, this method adds the category of photochemical oxidation for smog
formation, which has impacts resulting largely from coal combustion and secondarily
from coal mining and preparation. It is also shown here that CCP disposal almost
exclusively accounts for the impacts to human and ecosystem toxicity. CCP beneficial
use impacts are practically zero for all of the categories, although it must be remembered
Human
toxicity soil
Human
toxicity water
Human
toxicity air
Ecotoxicity
water acute
Ecotoxicity
water chronic
Photochemical
smog
Eutrophication
Acidification
Ozone
depletion
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Global
warming
% Contribution by life-cycle stage to total
category impact
that emissions from use and disposal of products made with CCPs are neglected.
Impact category
Coal Mining and Preparation
Coal Combustion
CCP Beneficial Use
CCP Disposal
Figure 3-5: EDIP impact characterization
The EDIP impact assessment method produces similar results to the other
methods with respect to global warming, ozone depletion, acidification, eutrophication,
and photochemical smog. The major discrepancy in this model is the characterization of
impacts in categories of human and ecosystem toxicity. The EDIP method indicates that
ecosystem toxicity is caused primarily by coal mining and preparation processes,
80
including the disposal of coal tailings and cleaning wastes. These results differ from
those presented by the first two methods in that the Eco-indicator 99 and CML methods
show ecotoxicity as being impacted by CCP disposal rather than coal mining and
preparation. The reason for this disparity is in the methods’ different classifications of
specific emissions into each of the impact categories. For example, the CML method
contains over three times as many emissions contributing to each impact category than
does the EDIP method. However, the models show agreement that impacts to human
toxicity are caused on the most part by CCP disposal.
Normalization and damage assessment
Using the characterization results, the impacts were normalized to global impacts in
the year 2000. Normalization values were obtained from the CML impact assessment
method. This method was used for normalization because it included global normalizing
factors, rather than factors specific to a European country or region. Normalization
factors specific to the U.S. were not available in the methods used.
Each of the impacts was also classified into three damage assessment groups:
human health, ecosystem quality, and resource use. The human health category includes
impacts to climate change, ozone layer depletion, photochemical smog formation,
radiation, carcinogens, human toxicity, and respiratory organics and inorganics.
Ecosystem quality considers the total of impacts to acidification, eutrophication,
ecotoxicity, and land use, while resource use includes mineral resource and other abiotic
resource depletion. Presenting the results in terms of damage assessment allows for more
clear comparisons between life cycle stages through the use of generalized damage
categories and dimensionless quantities. The damage assessments of impacts to each of
the three damage categories for this LCA using normalized impacts are shown in Figure
81
3-6 through 3-8 for each life cycle stage and for the entire life cycle. The quantities
shown in each Figure represent the relative impact of each life cycle stage as compared to
Dimensionless impact to human
health
the global impacts during the year 2000.
8.00E-11
7.00E-11
6.00E-11
5.00E-11
4.00E-11
3.00E-11
2.00E-11
1.00E-11
0.00E+00
-1.00E-11
Coal Mining
and Preparation
Coal
Combustion
CCP Beneficial CCP Disposal
Use
Entire Life
Cycle
Life cycle stage
Figure 3-6: Normalized human health impacts from each life cycle stage
Results illustrated in Figure 3-6 indicate that the stages of coal mining and
preparation, coal combustion, and, only to a slightly greater extent, CCP disposal
contribute predominantly to damage to human health, primarily through the release of
compounds that have been shown to have health impacts associated with carcinogenesis,
respiratory diseases, global warming, and ozone depletion. Beneficial use appears to
prevent impacts to human health from occurring, but it must be considered that this result
does not consider the end-of-life scenarios of any products made with CCPs during the
beneficial use stage.
Dimensionless impacts to ecosystem
quality
82
1.20E-08
1.00E-08
8.00E-09
6.00E-09
4.00E-09
2.00E-09
0.00E+00
-2.00E-09
Coal Mining and
Preparation
Coal Combustion
CCP Beneficial
Use
CCP Disposal
Entire Life Cycle
Life cycle stage
Figure 3-7: Normalized ecosystem quality impacts from each life cycle stage
Ecosystem quality impacts are attributed almost entirely to CCP disposal.
Disposal impacts are greatest because of the large amount of land required for CCP
disposal and the release of trace metals and compounds that can create acidification and
Dimensionless impacts to resource
use
ecotoxicity in areas into which the CCPs are disposed.
3.50E-10
3.00E-10
2.50E-10
2.00E-10
1.50E-10
1.00E-10
5.00E-11
0.00E+00
-5.00E-11
Coal Mining
and Preparation
Coal
Combustion
CCP Beneficial CCP Disposal
Use
Entire Life
Cycle
Life cycle stage
Figure 3-8: Normalized resource depletion impacts from each life cycle stage
83
As shown by the SimaPro results in Figure 3-8, resource use is almost entirely
attributable to the processes required for coal mining and preparation. As compared to
the other life cycle stages, CCP beneficial use has a negligible impact to any of the
damage categories. Throughout the entire process life cycle, the greatest amount of
damage created is to ecosystem quality, followed by human health.
Interpretation
The results obtained from the LCI and the impact assessment were interpreted in
the context of the defined goal and scope: to determine environmental impacts associated
with the life cycle of CCPs, compare CCP disposal and beneficial use scenarios, and
create a decision tool for CCP management. Based on the inventory and impact
assessment results presented thus far, it has been shown that the highest percentage of
impacts from the life cycle of CCPs are created by disposal of these products in landfills
or surface impoundments. On the other hand, CCP beneficial use contributes the least of
all stages to the life cycle impacts, and in the case of raw material substitution, beneficial
use actually prevents impacts from occurring, indicated by negative impact values.
However, a conclusion about the comparative impacts between CCP disposal and
beneficial use would require sensitivity analysis on the LCA results and a direct
comparison between CCP management options.
Sensitivity analysis
Sensitivity analysis was performed to determine the robustness of the LCA model
results by changing system inputs and measuring the resulting change to life cycle
impacts. Eight inputs were chosen for sensitivity analysis based on their importance to a
particular life cycle stage and their potential for variation between different utilities and
operating systems. Descriptions of each of the inputs that were varied to perform
84
sensitivity analysis are given in Table 3-10. The base-case scenario refers to the system
that was used to create the LCA model, as discussed previously
Table 3-10: Input variations used to perform sensitivity analysis
Analysis No.
0
1
2
3
4
5
6
7
8
Description of Sensitivity Analysis
Base-case scenario
100% surface mining and 0% underground mining
0 % surface mining and 100% underground mining
Coal cleaning at mine mouth
100% rail transportation of coal to the utility
25% increase in electricity generated
No FGD material production/no increase in SO2 emissions
Beneficiation on fly ash, bottom ash, and FGD before beneficial use
Lined containment systems for landfills and surface impoundments
Measures 1 and 2 were used to determine the effect of source coal on the life cycle
of the CCPs. Changing coal cleaning in analysis 3 to the mine mouth rather than 25
miles from the mine illustrates the impact of that transportation requirement. In measure
4, 100% transportation to the utility by train is used, rather than a mix of transportation
by rail, road, and barge. Measures 5 and 6 assess the variability of the life cycle results
due to changes in the stage of coal combustion. Beneficiation is considered in analysis 7
to determine if the addition of infrastructure and energy requirements before CCP
beneficial use will diminish the environmental advantage that accrues from CCP use.
Analysis 8 is used to determine if impacts from CCP disposal are highly sensitive to the
presence or absence of a geotechnical membrane or other liner for landfills and surface
impoundments. The changes resulting from each of these variations was quantified for
each life cycle stage to determine the susceptibility of impacts from one stage to changes
in a different stage. The relative changes associated with each of these analyses are
presented in Tables 3-11 through 3-14 for each impact category and life cycle stage.
85
Values presented are the percent change from the base-case scenario. Negative
percentages indicate that the input variation created a decrease in impacts from the life
cycle stage.
Table 3-11: Sensitivity analysis results for coal mining and preparation
Impact category
Unit
1
2
3
4
5
6
7
8
Carcinogens
DALY
-9.3%
13.8%
-0.5%
-1.2%
-85.2%
0.0%
0.0%
0.0%
Resp. organics
DALY
0.0%
0.0%
-0.6%
-1.9%
-99.2%
0.0%
0.0%
0.0%
Resp. inorganics DALY
-1.5%
2.3%
-1.5%
-2.3%
90.2%
0.0%
0.0%
0.0%
Climate change
DALY
-22.1% 33.6%
-2.3%
-3.9%
180.4%
0.0%
0.0%
0.0%
Radiation
DALY
-12.1% 18.1%
-1.0%
7.0%
-90.5%
0.0%
0.0%
0.0%
Ozone layer
DALY
-0.3%
-0.8%
-99.3%
0.0%
0.0%
0.0%
Ecotoxicity
Acidification/
Eutrophication
PDF*m2yr -49.8% 74.6%
-4.2% -12.7%
6.8%
0.0%
0.0%
0.0%
PDF*m2yr
-3.8% -10.6%
40.9%
0.0%
0.0%
0.0%
Land use
PDF*m2yr 12.9% -20.2% -3.4%
-4.5%
-96.6%
0.0%
0.0%
0.0%
Minerals
MJ surplus -3.2%
-7.0% -14.0%
-73.7%
0.0%
0.0%
0.0%
0.3%
2.3%
-0.5%
-3.0%
5.4%
As shown in Table 3-11, changing the source coal and coal transportation factors
and increasing the demand for coal required by higher electricity production (represented
by analyses 1-5) produced varying levels of response in the impacts associated with the
coal mining and preparation life cycle stage. According to the SimaPro results, this stage
showed the highest sensitivity to changes in the mining method used to extract coal and
in the demand for coal created by changes in electricity production. On the other hand,
the impacts from coal mining are unchanged during changes to CCP management
variables, indicating that this stage is very resistant to changes far-removed in the process
chain.
86
Table 3-12: Sensitivity analysis results for coal combustion
Impact category
Unit
1
2
3
4
5
6
7
8
Carcinogens
DALY
0.0%
0.1%
0.0%
0.0%
758.8%
0.0%
0.0%
0.0%
Resp. organics
DALY
0.0%
0.0%
0.0%
0.0%
15111.8%
0.0%
0.0%
0.0%
Resp. inorganics DALY
0.0%
0.0%
0.0%
0.0%
-33.0%
0.0%
0.0%
0.0%
Climate change
DALY
0.0%
0.0%
0.0%
0.0%
-54.6%
0.0%
0.0%
0.0%
Radiation
DALY
0.0%
0.0%
0.0%
0.0%
1244.6%
0.0%
0.0%
0.0%
Ozone layer
DALY
0.0%
0.0%
0.0%
0.0%
17873.0%
0.0%
0.0%
0.0%
Ecotoxicity
Acidification/
Eutrophication
PDF*m2yr
0.0%
0.0%
0.0%
0.0%
18.9%
0.0%
0.0%
0.0%
PDF*m2yr
0.0%
0.0%
0.0%
0.0%
-10.2%
0.0%
0.0%
0.0%
Land use
PDF*m2yr
0.0%
-0.2%
0.0%
0.0%
3679.2%
0.0%
0.0%
0.0%
Minerals
MJ surplus
0.0%
0.0%
0.0%
0.0%
381.9%
0.0%
0.0%
0.0%
Sensitivity analysis for coal combustion produced very unusual results, as shown in
Table 3-12. This life cycle stage is virtually unaffected by any changes to the coal
supply, transportation requirements, and the production and management of CCPs.
However, coal combustion impacts are highly sensitive to a change in the electricity
produced for a given system. The number 5 analysis increased electricity generation by
25% within a system in which all other combustion variations were kept constant, but
produced changes in relative impacts of up to and over 17000%. The considerable
variation in relative impacts indicates that the system modeled in this LCA cannot simply
be scaled up or down by the amount of electricity produced. To assess a generating
system with different kWhr capacity, specific operating parameters for the system in
question must also be changed to obtain reliable and reproducible results. It is
encouraging, however, to note that the stage of coal combustion does not exhibit high
sensitivity to any other impact variation. Therefore, it is believed that fine tuning the
87
combustion model and specifying variables that were specific to a given generating
system would eliminate the extreme variation in the impacts.
Table 3-13: Sensitivity analysis results for CCP beneficial use
Impact category
Unit
1
2
3
4
5
6
7
8
Carcinogens
DALY
0.5%
-0.7%
0.0%
0.0%
0.0%
8.3%
9.2%
0.0%
Resp. organics
DALY
0.0%
0.0%
0.0%
0.0%
0.0%
54.3%
2.6%
0.0%
Resp. inorganics DALY
0.0%
0.0%
0.0%
0.0%
0.0%
39.1%
2.2%
0.0%
Climate change
DALY
0.0%
0.0%
0.0%
0.0%
0.0%
30.5%
1.1%
0.0%
Radiation
DALY
0.3%
-0.6%
0.0%
0.0%
0.0%
0.3%
14.4%
0.0%
Ozone layer
DALY
-0.1%
0.1%
0.0%
0.0%
0.0%
70.6%
2.6%
0.0%
Ecotoxicity
Acidification/
Eutrophication
PDF*m2yr
5.7%
-8.9%
0.0%
0.0%
0.0%
-136.9% 89.6%
0.0%
PDF*m2yr
0.0%
0.0%
0.0%
0.0%
0.0%
28.3%
1.5%
0.0%
Land use
PDF*m2yr
0.0%
0.5%
0.0%
0.0%
0.0%
76.8%
63.1%
0.0%
Minerals
MJ surplus
0.0%
-0.4%
0.0%
0.0%
0.0%
-70.6%
72.0%
0.0%
The life cycle stage of CCP beneficial use shows low levels of sensitivity to
variation in coal source inputs, transportation requirements, and CCP disposal practices.
However, the elimination of FGD material from the CCPs being produced and the
addition of beneficiation as a process step in CCP beneficial use, analyses 6 and 7,
respectively, produced significant impact variation. In analysis 6, FGD material is
eliminated to represent a utility with no SO2 control system, but assuming that SO2
emissions are not increased. This variation produced mixed results, with most of the
impact categories increasing in total impact, from the lack of FGD material as a substitute
for raw materials in other processes. However, impacts to ecotoxicity and mineral use
both decreased without FGD material production for several reasons. When FGD
material is not produced, there is no need for FGD equipment or sorbents or for
transporting the FGD material to offsite beneficial use markets. On the other hand,
88
including the FGD material, but requiring beneficiation on fly ash, bottom ash, and FGD
material creates increased impacts in every one of the impact categories. Beneficiation
requires energy and equipment and, therefore, decreases the environmental benefit
accrued by using rather than disposing CCPs. To note however, in none of the impact
categories is the percentage change greater or equal to 100%, indicating that beneficial
use still creates low or no environmental impacts for the system considered, without
taking into account the use and disposal of any products made using CCPs.
Table 3-14: Sensitivity analysis results for CCP disposal
Impact category
Unit
1
2
3
4
5
6
7
8
Carcinogens
DALY
0.0%
0.0%
0.0%
0.0%
0.0%
-53.2%
0.0%
-50.6%
Resp. organics
DALY
0.0%
0.0%
0.0%
0.0%
0.0%
-56.3%
1.4%
27.5%
Resp. inorganics DALY
0.0%
0.0%
0.0%
0.0%
0.0%
-56.5%
1.8%
14.3%
Climate change
DALY
0.0%
0.0%
0.0%
0.0%
0.0%
-56.2%
1.9%
9.9%
Radiation
DALY
0.0%
0.0%
0.0%
0.0%
0.0%
-56.5%
1.6%
0.4%
Ozone layer
DALY
0.0%
0.0%
0.0%
0.0%
0.0%
-56.4%
1.6%
10.9%
Ecotoxicity
Acidification/
Eutrophication
PDF*m2yr
0.0%
0.0%
0.0%
0.0%
0.0%
-0.2%
0.0%
-51.1%
PDF*m2yr
0.0%
0.0%
0.0%
0.0%
0.0%
-55.9%
1.7%
6.0%
Land use
PDF*m2yr
0.0%
0.0%
0.0%
0.0%
0.0%
-52.3%
1.4%
0.0%
Minerals
MJ surplus
0.0%
0.0%
0.0%
0.0%
0.0%
-55.1%
1.7%
1.0%
The CCP disposal stage only shows sensitivity to changes in CCP production and
management. In analysis 6, removal of FGD material previously generated decreased the
disposal impacts by about 50% in most of the categories, a decrease proportionate to the
fraction of FGD material that would be disposed under the given conditions of 50%
beneficial use and 50% disposal. Interestingly, however, the decrease in impact to
ecotoxicity from elimination of FGD material was very small, indicating that its disposal
is not a major contributor to release of materials that create ecotoxicity. In analysis 8, the
89
landfill and surface impoundments used for CCP disposal are assumed to have liners
made of high-density polyethylene (HDPE) that reduce by half the output of compounds
from the disposal site to surrounding water and soil. The impacts from carcinogens and
ecotoxicity are each reduced by about 50%, as trace elements and other potentially
damaging compounds are prevented from leaching out of the disposal site. However,
impacts in the other categories increase slightly from production and use of the liner. It
can be concluded that the CCP disposal stage is sensitive to changes in CCP production
and disposal variables, but resistant to variations in other life cycle stages.
The changes due to each of the sensitivity analyses were aggregated according to
damage assessment categories and summed to obtain the total life cycle impacts. These
Percent change from base case scenario
results are presented in Figure 3-9, according to the number of the analysis performed.
10%
5%
0%
-5%
-10%
-15%
-20%
-25%
-30%
-35%
-40%
1
2
3
4
5
6
7
Sensitivity analysis number
Human Health
Ecosystem Quality
Resources
Figure 3-9: Relative change to damage categories due to sensitivity analyses
8
90
Aggregating the changes in impacts into damage categories eliminates much of the
variation seen previously between categories and between life cycle stages. For analyses
1 through 5 and 7, the life cycle sensitivity to perturbation is within about 10%. In
scenarios 6 and 8, the variation in results is much higher, indicating that the impacts from
CCP generation and disposal procedures appear to have a significant effect on the
SimaPro results that were calculated for impact assessment in each of the four life cycle
stages.
Comparison of CCP management scenarios
In creating the base-case scenario that was used to model the CCP LCA, three basic
assumptions were made: 1) 50% of all CCPs would be beneficially used and 50% would
be disposed; 2) CCPs that were disposed would be divided such that half would be
landfilled and the other half would be placed in surface impoundments; and 3) the CCPs
that were beneficially used would be transported 50 miles to their final use in a beneficial
application. For a final comparison between CCP management options, these three
conditions were alternatively varied to determine the best CCP management options from
an environmental perspective.
Comparison of disposal to beneficial use. The environmental impacts associated
with each of the three damage categories were calculated for increasing levels of CCP
beneficial use and decreasing amounts of CCP disposal. In this comparison, the baseline
was taken to be 100% CCP disposal with equal amounts designated for landfill and
surface impoundment. The level of CCP beneficial use was increased from 0 to 100
percent, as shown in Figure 3-10.
Relative impact compared to
100% CCP disposal
91
100%
80%
60%
40%
20%
0%
-20%
100% CCP
Disposal
25% CCP
Beneficial
Use
50% CCP
Beneficial
Use
75% CCP
Beneficial
Use
100% CCP
Beneficial
Use
CCP management scenario
Human Health
Ecosystem Quality
Resources
Figure 3-10: Comparison of CCP disposal and beneficial use
This comparison indicates that increasing levels of CCP beneficial use are
environmentally preferable to CCP disposal. Although impacts to resource use were
relatively constant in all the scenarios, the impacts to human health and ecosystem quality
decreased sharply with increasing beneficial use. This result is not surprising, as
beneficial use not only decreases the raw material requirements in the life cycles of the
products into which the CCPs are exported, but it also minimizes the potential for trace
metals and other contaminants to enter the environment from disposal sites. Rather, these
compounds are stabilized and fixated in the products made by CCP beneficial use,
decreasing their potential for re-evolution into the environment.
Comparison of CCP disposal methods. Although the results presented here
indicated that the most environmentally preferable CCP management option would be to
use 100% of the products generated, this is not always a feasible option. Transportation
92
costs, market limitations, and CCP quality all pose limitations to the extent to which these
products can be used. Therefore, it is necessary to compare disposal methods to
determine the best options for managing CCPs that cannot be beneficially used. For this
comparison, 100% CCP landfill was considered the base case to compare with increasing
Relative impact compared to
100% CCP landfill
levels of surface impoundment use, as shown in Figure 3-11.
120%
100%
80%
60%
40%
20%
0%
100% CCP
Landfill
75% Landfill / 50% Landfill / 25% Landfill / 100% CCP
25%
50%
75%
Impoundment
Impoundment Impoundment Impoundment
CCP disposal scenarios
Human Health
Ecosystem Quality
Resources
Figure 3-11: Comparison of CCP disposal options
The comparison of CCP disposal options indicates that comparative impacts
between the scenarios vary according to the damage category considered. From the
perspective of human health, impacts increase with increasing use of surface
impoundments. On the other hand, use of surface impoundments instead of landfills
decreases impacts to ecosystem quality and resource use, primarily because of the smaller
size and lower equipment and infrastructure requirements associated with constructing
and operating a surface impoundment. A definitive choice between these two options
would also have to be based on other decision criteria, including the relative cost of both
93
disposal options, the lifetime of CCPs after disposal (whether or not they are harvested
for beneficial use or another disposal option), the human exposure potential in the area
around the utility, and the sensitivity of the ecosystem where the CCPs are disposed. As
the results here are not entirely conclusive, it appears that environmental impacts could
be minimized by a combination of the two disposal scenarios, with percent contributions
according to site-specific conditions and environmental or human health priorities.
Comparison of CCP beneficial use transportation distances. In the base-case
scenario, 50 miles was chosen as the representative distance that the CCPs would be
transported from the utility to the beneficial use market. Utilities often have to subsidize
some or all of the transportation costs for CCP use, and it is therefore desirable to
minimize the distance required. The scenarios assessed here use 50 miles as a baseline
and compare distances between 0 and 1000 miles from the utility, shown in Figure 3-12.
Relative impact compared to 50
miles
1800%
1600%
1400%
1200%
1000%
800%
600%
400%
200%
0%
0
25
50
75
100
150
200
500
1000
Distance from utility to beneficial use market (miles)
Human Health
Ecosystem Quality
Figure 3-12: Comparison CCP transportation scenarios
Resources
94
As shown in Figure 3-12, the impacts to human health and ecosystem quality only
increase slightly, about 7.6 and 1.3%, respectively. However, impacts to resources used
increased almost exponentially to almost an 1800% at 1000 miles over the baseline of 50
miles. Based on these findings, it is obvious that the most environmentally preferably
option for CCP transportation would be a beneficial use market that is adjacent or very
close to a utility that is generating and selling CCPs. Considering the results of Figure 310 as well, it should be noted that increasing the level of CCP beneficial use by sending
the CCPs to markets that are distances greater than about 200 miles from the utility can
begin to negate the environmental benefit accrued from using these products.
Conclusions
The SimaPro LCI, impact assessment, and interpretation results present a
convincing case that CCP disposal presents a high risk to environmental and human
health when compared to the entire life cycle of CCPs. These results show the highest
sensitivity to the amount of electricity produced, the type and quantity of CCP generated,
and the conditions under which the CCPs are managed. In terms of CCP management,
this LCA indicated that under general conditions, beneficial use of CCPs is
environmentally preferable to disposal. However, little is known of potential impacts on
environment and human health from CCPs in beneficial use applications. To minimize
environmental impact, the amount of CCPs used in a beneficial application should be
increased to the highest level possible, within a 200 mile, or less, radius of the utility at
which they were generated. The best alternative would be CCP beneficial use at a facility
located adjacent to the electric utility, similar to eco-industrial parks espoused by the
concepts of industrial ecology. As it is likely that not all CCPs generated can be used in a
beneficial application, the LCA results indicate that they should be disposed of in a
95
combination of a lined landfill and a lined surface impoundment. The amount designated
for each disposal method would vary based on site-specific conditions and environmental
and human health priorities.
CHAPTER 4
RECOMMENDED BEST MANAGEMENT PRACTICES FOR COAL COMBUSTION
PRODUCTS AT FLORIDA UTILITIES
Introduction
The beneficial use of CCPs can create economic and environmental benefits for
CCP generators, CCP marketers, and industry. From an economic perspective, CCP use
provides sales revenue and decreases disposal infrastructure, equipment, and operating
costs. Environmental benefits include reduced CCP disposal in landfills and surface
impoundments, decreased greenhouse gas emissions, and avoided extraction and
processing of virgin raw materials that the CCPs can replace. In addition to these
obvious benefits, CCP use in engineering materials and construction applications can
increase their performance and durability (Deinhart et al., 1998; Gainer, 1996).
Although CCP beneficial use could present a waste management solution for
utilities, regulators, and industry, the majority of these products are continually disposed
in landfills and surface impoundments. Improper handling or disposal of these products
has the potential to create human health and environmental impacts, although these
impacts have not been fully characterized or compared to those associated with CCP
beneficial use. To this end, an LCA was performed to determine the environmental
impacts associated with the life cycle of CCPs and to compare disposal and beneficial use
(Chapter 3). This LCA has shown that under certain conditions, beneficial use of these
products is environmentally preferable to their disposal in landfills or surface
impoundments. However, the beneficial use of CCPs is still less than 30% in the U.S.,
96
97
indicating that a significant gap exists between beneficial use potential and actual
practice. This disparity is caused by a number of limitations, including lack of standards
for beneficial use applications, CCP transportation costs, regulatory issues, lack of
governmental incentive, lack of education in and cooperation between user groups,
uncertainty as to human health and environmental impacts, lack of awareness of potential
beneficial use markets, and public and industry perception of these products (Kalyoncu
and Olson, 2001).
These limitations can begin to be addressed with a thorough assessment of the
characteristics of CCPs generated in Florida, the current and emerging markets for CCP
beneficial use, and the trends in disposal practices. Therefore, the objective of this
chapter is to investigate these issues and formulate best management practices (BMPs)
for CCPs generated at Florida utilities from a life cycle perspective. These BMPs are
recommended for regulators and CCP generators to consider as beneficial use and
disposal practices are established to minimize or prevent impact to human and
environmental health.
Methods
The assessment of potential and practicable BMPs was conducted by collecting
utility-specific operating and CCP management information from coal-fired utilities in
Florida; characterizing the state of CCP generation, beneficial use, and disposal within
the state; and analyzing each process during beneficial use and disposal life-cycle stages
from an LCA perspective.
Data Collection
Twelve of Florida’s 55 utilities combust coal as their major fuel source. Four of
these utilities were identified by the Florida Department of Environmental Protection
98
(FDEP) and the Florida Electric Power Coordinating Group (FCG) as being
representative of general operating procedures in Florida. Visits and interviews were
conducted at these four utilities to determine the state of CCP generation, beneficial use,
and disposal. Surveys were administered to the remaining eight utilities with a 37.5
percent return rate, with three utilities completing and returning the surveys. Surveys
were also administered to ten companies identified by the American Coal Ash
Association (ACAA) as currently engaging in CCP marketing and use. Copies of the
survey tools used to collect data are given in Appendix B.
Characterization of CCP Generation, Beneficial Use, and Disposal in Florida
Data collected were compiled to create a representation of the state of CCP
generation, beneficial use, and disposal in Florida. This assessment was based on the
quantities of CCPs generated, the relative percentage of CCPs currently being
beneficially used, and the methods of disposal used. CCP beneficial use was
characterized by the current markets in which these products are being used in the state.
Other trends in disposal practices and emerging CCP markets were also identified.
Creation of BMPs
BMPs were created to pinpoint specific practices that minimize or prevent impacts
to human and environmental health that could potentially be caused from beneficial use
or disposal of CCPs. These practices focus only on the processes in the final two life
cycle stages of the entire CCP LCA: beneficial use and disposal. Processes in the
beneficial use stage include CCP storage and handling, beneficiation, CCP transportation
to an end use, and beneficial use by material replacement (Level 2.3 in Figure 3-2).
Disposal stages include storage and handling, CCP treatment and fixation, disposal in a
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landfill or long-term storage, and disposal or storage in a surface impoundment (Level
2.4 in Figure 3-2).
Results and Discussion
Characterization of CCP Generation, Beneficial Use, and Disposal in Florida
The amounts and types of each CCP generated in Florida depend on the operating
parameters and fuel sources at each utility in the state. Fly ash and bottom ash are
produced from every utility, whereas boiler slag is produced only at those limited utilities
using wet-bottom boilers in the generating system. FGD material is produced only at
utilities using SO2 control technology. Operating conditions and fuel source also
influence the type and percent of beneficial use. A summary of generation, beneficial
use, and disposal is presented in Table 4-1.
Table 4-1: Characterization of CCPs generation, use, and disposal in Florida.
Site
1
2
3
4
5
6
8
Power Station
Crist
Big Bend
McIntosh
Crystal River Deerhaven
Smith
Scholtz
Location
Pensacola
Tampa
Lakeland
Crystal River Gainesville
Lynn Haven Sneads
Production
(tons per year)
144,000
267,250
80,918
505,000
48,000
42,821
11,229
Fly Ash
Beneficial Use
(%)
82.6%
99.6%
0.0%
94.5%
91.7%
0.0%
0.0%
Production
16,000
21,819
12,250
50,000
12,450
10,705
2,807
Bottom (tons per year)
Ash
Beneficial Use
(%)
0.0%
100.0%
0.0%
44.0%
0.0%
0.0%
0.0%
Production
(tons per year)
0
77,132
0
0
0
0
0
Boiler
Slag
Beneficial Use
(%)
0.0%
87.1%
0.0%
0.0%
0.0%
0.0%
0.0%
Production
(tons per year)
0
819,261
160,826
0
0
0
0
FGD
Material Beneficial Use
(%)
0.0%
92.5%
0.0%
0.0%
0.0%
0.0%
0.0%
Disposal Method
Landfill
Landfill and
Impoundment
Landfill
Landfill
Landfill
Landfill and
Impoundment Impoundment
As discussed previously, variation between different levels of CCP generation and
beneficial use shown in Table 4-1 is attributable to the broad differences in operating
parameters and fuel sources at the different utilities. For example, the Big Bend
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generating system is the only one that generates boiler slag, owing to its use of wetbottom boilers in one part of their generating system. On the other hand, most utilities
used dry-bottom boilers and produced bottom ash instead of boiler slag. The Big Bend
and McIntosh generating stations are the only two utilities to use FGD systems for SO2
control and, therefore, are the only sites to produce FGD material. Other utilities
eliminate the need for SO2 control by burning low-sulfur coal or coal in a combination
with or in addition to other fuel sources, such as petroleum coke or fuel oil.
Different fuel sources also account for much of the variation in the levels of
beneficial use between sites. For example, the McIntosh generating site is unique in that
it burns coal combined with municipal solid waste. The varying composition and
moisture content of the refuse feedstock creates a constantly changing composition and
LOI in the CCPs generated. These changing parameters make it unfeasible for the utility
to sell these products to markets such as the cement industry that require low LOI and
consistent product characteristics. In addition, the McIntosh site is a public utility and
cannot easily justify or obtain the funds necessary to beneficiate the CCPs to a quality
level necessary for beneficial use in common markets. Therefore, the fly ash, bottom ash,
and FGD sludge are combined with free lime to produce a pozzolanic material that forms
a relatively impermeable cementitious material that is disposed on-site.
In terms of disposal practices, most utilities use landfills as the final disposal
destination for CCPs that are not beneficially used. Others use a combination of landfills
and surface impoundments, where the impoundments are generally ash ponds or lagoons.
At some sites, the surface impoundment is also managed as a temporary holding location
for CCPs that will be eventually sold for beneficial use. Although the same practice is
101
not used for landfills, some utilities are able to extract, or “harvest,” the CCPs that were
disposed in landfills and sell them to a beneficial use market. In this case, the CCPs have
been in the landfills for periods up to and exceeding a year and have undergone physical
changes that make them unusable for some applications, such as Portland cement
replacement. A general practice at utilities is to line landfills with a CCP or a CCP
derivative, such as bottom ash or a pozzolanic ash-lime-FGD material blend. However,
some sites line the landfills with engineering materials, such as bentonite or a
geotechnical membrane. Utilities using ash lagoons for handling or long-term storage of
CCPs are trending towards the use of synthetic liners, although in many cases these
impoundments are unlined.
CCP Beneficial Use BMPs
Accepted and common beneficial use markets for CCPs in Florida include fly ash
substitution for Portland cement or mineral admixture in concrete, bottom ash use in
lightweight aggregate, boiler slag use in roofing granules, blasting grit, and aggregate,
and FGD gypsum substitution for other gypsum materials for wallboard manufacture.
Within the utility sites, CCPs are often used in small quantities for more varied
applications, including daily landfill cover, road covering, and waste stabilization. CCP
generators are also very interested in creating and expanding markets for structural fill
and road base and subbase.
Storage and handling
Fly ash and bottom ash can be stored wet or dry before leaving the utility for a
beneficial use application. Dry ash is pneumatically conveyed to an above-ground silo,
where it is stored until discharged into a truck for transportation to the beneficial use
market. Ash stored wet is combined with water and sluiced to an ash pond and stored
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until it is required for sale. A common practice in operating ash ponds is to maintain one
half as an active side, where ash is continuously inputted, and the other half as the
harvesting side, where water is removed and the ash is subsequently exported for sale.
Gypsum and boiler slag can also be handled in wet or dry systems, depending on the
nature of the process and the physical properties of the product being generated.
According to a LCA comparison, impacts to human health, ecosystem quality and
resource consumption, were higher for wet storage than for dry storage as shown in
Relative Impact to Damage
Categories
Figure 4-1.
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Dry storage
Wet storage
Human Health
Ecosystem
Quality
Resources
Damage Categories
Figure 4-1: Comparison of dry and wet storage systems.
Impacts from dry storage are attributed to the dust that is generated during storage and
handling. However, wet storage produces impacts from the higher infrastructure
requirements and the potential of trace metal and other compounds leaching from an
unlined pond in surface or groundwater. Therefore, it is environmentally preferable to
use dry handling systems for managing CCPs, with the requirement of dust control
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systems at points where CCPs are exposed to the atmosphere. A caveat to this
assessment is that the results are based on the construction and operation of new storage
systems, not the deconstruction and replacement of existing systems. Over a short time
horizon, it would be preferable that utilities with wet storage systems already in place
continue to use these with efforts in place to minimize and monitor contaminant
excursions, install liner systems, and switch to a dry system, if possible, after the life
cycle of existing systems is complete.
Beneficiation
Beneficiation is a general term to describe any process that improves the quality or
consistency of a product. In this context, beneficiation refers to processing CCPs to make
them more marketable for beneficial use. Two common examples are processing high
carbon fly ash to decrease the LOI and oxidizing FGD material to produce commercialgrade gypsum. These examples were examined with the assumption that without
beneficiation, the fly ash and FGD product would not be beneficially used and would
have to be disposed of. While this assumption is not universally true, it is generally
reasonable, as industry standards prevent or at best, limit the use of ash or FGD material
that does not meet high quality standards.
These comparisons assumed that the beneficiated CCP would be transported 50
miles to its final use market. The comparison between FGD material disposal and
production and sale of FGD gypsum was performed assuming that beneficiation would be
performed by forced oxidation of the FGD product. Results of this comparison are
shown in Figure 4-2.
Relative Impact to Damage Categories
104
100%
0%
-100%
-200%
-400%
FGD Gypsum
Beneficial Use
with
Beneficiation
-500%
FGD Disposal
-300%
-600%
-700%
-800%
Human Health
Ecosystem
Quality
Damage Category
Resources
Figure 4-2: Comparison of FGD disposal and FGD gypsum use with beneficiation.
As illustrated in Figure 4-2, in terms of resources used, the additional energy and
infrastructure requirements associated with beneficiation required to produce wallboardgrade FGD gypsum slightly decrease the benefit garnered from minimizing the use of
phosphogypsum or other gypsum products in wallboard manufacture and preventing
FGD material disposal. The major impact to resources is from construction and operation
of infrastructure and equipment necessary to transport the gypsum for sale up to 50 miles
from the utility. However, there is a significant comparative benefit from FGD gypsum
use when considering human health impacts. FGD gypsum beneficial use prevents over
700 percent of the magnitude of impacts that would be created by disposing of the FGD
material if not beneficiated. Beneficial use also has an advantage of 100 percent over
disposal in terms of impacts to ecosystem quality. Therefore, it is in the best interest of
human and environmental health for utilities to make every effort to create a marketable,
high quality gypsum product for sale to the wallboard and other industries. Furthermore,
105
the benefits of FGD gypsum beneficial use are increased when distance from the utility to
the beneficial use market are decreased.
The comparison between fly ash disposal and beneficial use requiring beneficiation
was conducted assuming that the fly ash would be processed using a high efficiency
triboelectric separator that removes unburned carbon particles from the bulk of the fly
ash. This common separator operates by triboelectrically charging fly ash particles by
interparticle contact and then collecting the positively charged carbon and the negatively
charged mineral content on opposing electrodes (Bittner and Gasiorowski, 2001). A
representative schematic of this process is shown in Figure 4-3. The results of this
comparison are shown in Figure 4-4.
From STI, 2003
Figure 4-3: Schematic of a triboelectric fly ash beneficiation system
Relative Impact to Damage Categories
106
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
-10%
Fly Ash
Beneficial Use
with
Beneficiation
FA Disposal
Human Health
Ecosystem
Quality
Resources
Damage Category
Figure 4-4: Comparison of fly ash disposal and fly ash use with beneficiation.
In each of the damage categories, impacts from fly ash disposal are reduced or
prevented by beneficial use, even considering the additional energy and infrastructure
required for beneficiation. Impacts to human health and ecosystem quality from
beneficial use are over 100 percent less than the impacts from fly ash disposal.
Furthermore, the resource use for beneficial use is only 60 percent of the resource impact
from fly ash disposal, even considering the resources required to construct and operate
the transportation infrastructure needed to deliver the fly ash to its final use destination.
Therefore, beneficiation and sale for a beneficial application would be the recommended
best management practice for high carbon fly ash. Although it is not considered in this
comparison, this method of separation also produces a carbon product that can be used as
a fuel source in the utility boiler furnace, reducing coal use by a small, but potentially
significant amount. The benefits from using this almost pure carbon fuel source are
expected to increase the environmental and economic advantage of beneficial use with
107
beneficiation over disposal. However, this comparison also does not take into account
economic assessment of the value of using recycled carbon in place of purchased coal,
increased market value of the low LOI fly ash, or the capital and operating cost of the
beneficiation system.
Transportation to beneficial use market
Results of the LCA on CCPs have shown that environmental impacts associated
with beneficial use increase with increasing distance that the CCPs have to be transported
to a beneficial use market. However, most utilities are located within a radius of up to
about 100 miles from the end use of the CCPs generated. Therefore, it will likely be
necessary to transport the CCPs over varying distances to maximize the percent that are
beneficially used without decreasing the economic value of their beneficial use. To
assess the importance and best practices of transportation, six scenarios were compared,
as shown in Table 4-2. These scenarios were created under the assumption that the
percent of CCPs that can be beneficially used by an existing market will increase with an
increasing radius of transportation distance around the utility.
Table 4-2: Scenarios for comparing transportation requirements and beneficial use
Miles from Percent of
Increase in
Comparison the utility
CCPs used percent used
1
0
5%
---
2
25
15%
10%
3
50
30%
15%
4
100
50%
20%
5
150
75%
25%
6
250
100%
25%
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To compare the economic costs and benefits of these scenarios, information
provided by CCP marketers and industry research was used to create the following
assumptions:
•
fly ash sales value is $15 per ton,
•
bottom ash, boiler slag, and FGD material have a combined average of $5 per ton,
•
fly ash represents 75% of the total CCPs beneficially used,
•
bottom ash, boiler slag, and FGD material represent the remaining 25% of the total
CCPs beneficially used,
•
marketing fees and other costs are neglected, and
•
transportation costs are subsidized by the utility at a rate of $0.10 per ton per mile
(Kimlinger and Dobbs, 2001).
The comparison was performed using 30% beneficial use at 50 miles from the utility as
the baseline impact values, because 50 miles was the reference distance used in the CCP
LCA. Results from this assessment were compiled in Figure 4-5.
Based on the analysis of these six scenarios using SimaPro software by PRé
Consultants, the maximum economic profit would be realized at reuse percentage of 30
percent at 50 miles from the utility. The economic benefit of selling CCPs would still be
positive up to distances of 100 miles from the utility. However, this assessment assumes
that the utility is responsible for subsidizing part or all of the transportation costs. If this
is not the case, then the economic benefit will continue to rise with increasing beneficial
use, despite the transportation requirements. In terms of environmental effects, human
health and ecosystem quality impacts decrease with increasing percent of CCPs
beneficially used, regardless of the distance they must be transported. Impacts to
resource use increase drastically with increasing distances as shown below in Figure 4-5.
600%
$25.00
500%
$20.00
400%
$15.00
300%
$10.00
200%
$5.00
100%
$0.00
0%
-100%
Cost and benefit
Relative impact compared to 30% beneficial
use at 50 miles
109
5% at 0
miles
15% at 25 30% at 50 50% at
75% at
100% at
miles
miles
100 miles 150 miles 250 miles
Human Health
138%
123%
100%
69%
31%
Ecosystem Quality
136%
122%
100%
71%
36%
0%
Resources
63%
59%
100%
177%
314%
508%
CCP Sales Revenue
$0.63
$1.88
$3.75
$6.25
$9.38
$12.50
Transportation Cost
$0.00
$0.38
$1.50
$5.00
$11.25
$25.00
Total Cost/Benefit
$0.63
$1.50
$2.25
$1.25
($1.88)
($12.50)
($5.00)
-6%
Comparison scenario
Figure 4-5: Environmental and economic comparison of beneficial use and transportation
scenarios.
In the scenario illustrated in Figure 4-5 and discussed above, it is difficult to
distinguish the relative value or weight of each of the three damage categories, and,
therefore, it is almost impossible to draw clear-cut conclusions about transportation
BMPs. However, it should also be considered that increased beneficial use can also be
realized very close or adjacent to the power plant where beneficial use partnerships are
available. Two examples of this are found in Florida. The Big Bend facility sells most of
its FGD gypsum to National Gypsum, a wallboard manufacturer that opened a facility
adjacent to the power plant. The Crystal River facility sells a significant fraction of ash
110
products to Boral Materials, which produces a concrete roofing tile at a plant adjacent to
the Crystal River generating station.
These partnerships represent small-scale eco-industrial parks, in which industrial
activities are co-located so that the byproducts and waste material of one facility can
become the feedstocks for another (Graedel, 2001). An eco-industrial park is one
application of industrial ecology, the study of the interrelationships between industrial
and natural systems (Bishop, 2000). These eco-industrial partnerships represent BMPs
for CCP transportation. Environmental impacts and economic costs are minimized when
CCPs are used in high quantities in industries located close or adjacent to the utility.
Beneficial use
Current beneficial use practices rely heavily on industry heuristics, regulatory
approval, and CCP quality and demand. Most of the CCPs beneficially used in Florida
are directed to the cement, concrete, and construction industries, wallboard
manufacturing, and roofing granule and sand blasting operations. These applications are
traditionally associated with high-volume use of CCPs from electric utilities across the
nation. These markets have high demand in Florida, where construction activity is
continually rising to accommodate population growth. However, these are just a few of
the many types of beneficial uses for CCPs. Twelve beneficial applications were
analyzed from an LCA perspective to create BMPs for beneficial use. In each case, the
CCPs were considered to be direct substitutes for alternative materials on a mass basis.
Concrete and cement. Use of fly ash, bottom ash, and FGD material in cement
and concrete production has the highest annual beneficial use, over 13 million tons, or
37% of all beneficial use applications (ACAA, 2003). This rate is attributed to high
volumes of fly ash used as a Portland cement substitute in concrete production. A
111
comparison of these materials for concrete production was performed, with results
presented in Figure 4-6.
Comparative impacts to damage categories
100%
90%
80%
70%
Concrete
from fly ash
60%
50%
Concrete
from Portland
cement
40%
30%
20%
10%
0%
Human Health
Ecosystem
Quality
Resources
Damage category
Figure 4-6: Comparison of fly ash and Portland cement for concrete production.
As shown in Figure 4-6, human health and ecosystem quality impacts for fly ash
use are much smaller than for Portland cement, because of decreased energy
requirements in processing fly ash, preventing the extraction and processing of Portland
cement, and decreasing the amount of fly ash disposed at the utility. These benefits are
shown for 100 percent replacement of fly ash for Portland cement, but they show a trend
of increasing with increased use of fly ash. These results are negligibly changed when
beneficiation is used to obtain low LOI fly ash suitable for concrete production purposes.
On the other hand, impacts for resource use are about 45 percent higher for fly ash
than for Portland cement, chiefly because when this system is examined from a life cycle
112
perspective, the coal used when fly ash was produced must be included. However, it
must also be considered that fly ash is an inevitable by-product from electricity
generation and will continue to be produced, regardless of its use in beneficial
applications. Therefore, the recommended best management method for fly ash and other
CCPs is to continue and, if possible, increase the amount that is used in cement and
concrete production. This application also has high industry and regulatory support on a
state and national basis.
Structural fill. Sand, gravel, and some soils are used as structural fill materials in
embankments and construction base layers. Fly ash, bottom ash, FGD material, and
boiler slag have all been used as replacements for other structural fills. In this
application, CCP use is economically limited by the transportation costs, and relative
inexpensiveness of the traditional materials. However, in areas where structural fill
material is not readily available, CCPs can be an economical substitute. Their
environmental advantages and disadvantages compared to sand and gravel are shown in
Figure 4-7. Since transportation costs largely constrain this beneficial application, it was
assumed that the CCPs would require transportation of 50 miles or less from the utility.
As shown in Figure 4-7, there is a significant environmental advantage to using
CCPs instead of sand and gravel in structural fill from the standpoint of impacts to human
health and ecosystem quality. This advantage is not necessarily related to environmental
problems associated with sand and gravel production. Rather, the environmental benefit
accrues from preventing the CCPs from being disposed in landfills and surface
impoundments at the utility.
Comparative impact to damage categories
113
100%
80%
60%
40%
20%
Structural
fill from
CCPs
0%
-20%
Structural
fill from
sand and
gravel
-40%
-60%
-80%
-100%
Human Health
Ecosystem
Quality
Resources
Damage category
Figure 4-7: Comparison of CCPs and sand and gravel for structural fill.
In terms of resource use, CCP use again produces higher impacts, from the coal
extracted, processed, and combusted during electricity generation. In light of these
results, recommended best management of CCPs would be to use them in structural fill
applications under certain conditions. Since structural fill material does not require the
low LOI value needed for concrete production, this beneficial use would best serve the
CCPs that do not meet the quality standards of concrete production. In addition,
structural fill can, but does not necessarily, undergo cementitious reactions that would
stabilize the CCPs if they were used. Therefore, there is a potential that trace metals and
other contaminants could leach from the fill material to surrounding soil and water.
Therefore, toxicity testing by the Toxicity Characteristic Leaching Procedure (TCLP;
U.S. EPA Method No. 1311) or other standardized measure should be required of
contractors opting to use CCPs instead of traditional structural material.
114
Flowable fill. Fly ash can be combined with sand, Portland cement, and water to
produce a flowable fill for backfill, foundation stabilization, or manhole or well closure.
Fly ash in flowable fill replaces excavated soils and cement mixtures. Fly ash flowable
fill has been shown to improve performance and decrease energy and labor required for
traditional fills (Dienhart et al., 1998). Flowable fill made from fly ash and from
Comparative impacts to damage categories
traditional materials were compared, with results presented in Figure 4-8.
100%
90%
80%
Flowable fill
from fly ash
70%
60%
50%
Flowable fill
from
traditional
materials
40%
30%
20%
10%
0%
Human Health
Ecosystem
Quality
Resources
Damage category
Figure 4-8: Comparison of flowable fill made from fly ash and cement mixtures.
These results show that fly ash in flowable fill has environmental advantages to
traditional materials in the categories of human health and ecosystem quality. This
advantage is attributed to decreasing cement and energy requirements and preventing a
portion of fly ash generated from being disposed. Resource impacts are higher for fly ash
flowable fill, due to the use of coal associated with fly ash production. However, these
115
impacts are not as significant as the benefits obtained from fly ash use, even considering
that fly ash is used only in up to about 10 percent of the flowable fill mixture. This
beneficial use is recommended for fly ash, due to environmental and performance
benefits. Although flowable fill is a cementitious material, it is still recommended that
any fly ash designated for this use be monitored for high levels of hazardous trace metals.
Waste stabilization. CCPs, particularly fly ash and FGD material have been used
in a variety of waste management applications, including waste stabilization, daily
landfill cover, CCP landfill liner, and leachate treatment. It is difficult to assess these
applications on a life cycle basis, as they do not usually occur as a substitution for
another process or material. Therefore, general observations from utility and industry
practices will dictate the BMPs for waste stabilization with CCPs.
At utility operations, the use of CCPs for landfill liner and daily cover, where none
would be used otherwise, would be expected to provide environmental benefit at little to
no economic cost. When CCPs are combined with each other and with other waste
materials to produce a pozzolanic material for disposal, it is predicted that environmental
impacts from contaminant excursions will be decreased, as compared to disposing of the
materials without stabilization. For example, the McIntosh facility does not beneficially
use any CCPs, but instead combines bottom ash, fly ash, and FGD [limestone] scrubber
sludge to produce Pozz-o-tec, a pozzolanic material with a permeability of less than 10E6 cm/sec. Furthermore, lime used in FGD treatment is supplied from predominantly the
high-lime-content wastewater sludge from nearby water treatment facilities. This system
not only produces an impermeable material that shows little potential for leaching but
also creates a waste management solution for local water treatment facilities and reduces
116
consumption of purchased limestone. Systems such as this represent the recommended
best beneficial use practices for waste management and stabilization, particularly if CCPs
used cannot be designated for an alternative beneficial use due to quality constraints.
Agriculture and soil amendment. FGD material and fly ash have been used to
improve the nutrient quality and physical properties of soils for agricultural use. Their
use was compared to applying liming agents and other fertilizing material. Results of this
Comparative impacts to damage categories
comparison are presented in Figure 4-9.
100%
90%
80%
70%
60%
Soil
Amendment
from CCPs
50%
40%
Soil
Amendment
30%
20%
10%
0%
Human Health
Ecosystem Quality
Resources
Damage catagory
Figure 4-9: Comparison of soil amendment with CCPs and traditional materials.
In this comparison, the human health and resource impacts associated with
combustion and transportation in the life cycle of CCP generation are about 30 percent
greater than impacts from production of liming and fertilizing agents. However,
ecosystem impacts are significantly decreased with the use of CCPs, primarily because of
the avoided impacts of their disposal. These results do not include any impacts that may
117
be derived from application of CCPs to land. This comparison presents a mixed and
tenuous assessment of CCP use in agricultural applications. Creation of BMPs is greatly
complicated by other environmental factors, such as the potential for compounds in the
CCPs to migrate from their application point into terrestrial and aquatic ecosystems and
the risk and uncertainty associated with using CCPs as amendments for crops or
vegetation that may be consumed by humans, livestock, or other animals. Furthermore,
Florida has typically sandy soil and regular occurrences of heavy, intermittent rains,
factors that increase the possibility that CCP contaminants could leach from the
application area into other ecosystems. Based on the uncertainty associated with this
beneficial use, it is concluded that the recommended practice for agricultural applications
would be to require approval and testing on a case-by-case basis. Many other beneficial
applications create less environmental impacts and human health risks, and from a life
cycle perspective, would be recommended above soil amendment.
Road base, subbase, and pavements. In road base and subbase production and
use, fly ash and bottom ash can substitute for crushed stone or gravel base courses or for
cement used in concrete pavement. The beneficial use of CCPs in road construction was
assessed by comparing traditional base and pavements materials with bottom ash and a
lime-fly ash blend substituting for the base materials and fly ash substituting for a portion
of the cement required for concrete paving. Results from this comparison are illustrated
in Figure 4-10.
According to the results from SimaPro, the use of CCPs in road construction would
be expected to decrease human health and ecosystem quality impacts as compared to road
construction with traditional base and paving materials. However, the use of CCPs adds
118
impacts to resource depletion, due to the coal consumed in electricity generation when
Comparative impact to damage categories
the CCPs are generated.
100%
90%
80%
70%
Road construction
with CCPs
60%
50%
40%
Road construction
with traditional
base and paving
materials
30%
20%
10%
0%
Human Health
Ecosystem
Quality
Resources
Damage category
Figure 4-10: Comparison of road construction with and without CCPs.
Another factor in this comparison to consider is that this beneficial use is
commonly performed for small, secondary roads with low traffic volume (Shirazi, 1999).
Therefore, one ideal recommended practice would be to use CCPs for road construction
at or near the utility at which they are generated or at nearby industrial facilities, rather
than in residential areas. Uncertainty still exists about metal contamination around roads
constructed with CCPs, and, therefore, it is best to require toxicity testing on a regular or
annual basis for materials designated for this use.
119
Blasting grit and roofing granules. Boiler slag is the only CCP that is used for
producing roofing granules and blasting grit. Use of boiler slag in this application was
Comparative impact to damage categories
compared to use of sand, quartz, and crushed gravel. Results are shown in Figure 4-11.
100%
90%
80%
70%
60%
Blasting grit and
roofing granules
from boiler slag
50%
40%
Blasting grit and
roofing granules
from alternative
sources
30%
20%
10%
0%
Human Health
Ecosystem
Quality
Resources
Damage category
Figure 4-11: Comparison of roofing granule and blasting grit production with and without
boiler slag.
According to SimaPro results shown in Figure 4-11, use of boiler slag in roofing
granules and blasting grit has about 45 percent fewer impacts to human health and 85
percent fewer impacts to ecosystem quality than traditional aggregate material used in
these applications. This difference is attributable to decreasing the boiler slag disposal
rate and preventing dust and other particulate emissions from processing sand and other
high-silica-content materials. Resource use is higher for boiler slag due to the coal use in
electricity generation in the production stage of the CCP life cycle. On the other hand,
boiler slag use is expected to have negligible impacts due to metals excursions, as the
120
slag is a vitreous material that effectively traps metal and other contaminant particles.
Almost 60% of all boiler slag produced has been used in roofing granules or blasting grit,
and thus for this reason and because minimal expected environmental and human health
impacts are expected, this application is the best recommended practice for boiler slag
reuse.
Wallboard manufacture. FGD gypsum has been used as a substitute for natural
gypsum or phosphogypsum and other synthetic gypsums in the production of gypsum
wallboard. To assess this beneficial use, the life cycle of FGD gypsum and natural
Comparative impacts to damage categories
gypsum were compared, as shown in Figure 4-12.
100%
90%
80%
70%
60%
50%
FGD
Gypsum
40%
Natural
gypsum
30%
20%
10%
0%
Human Health
Ecosystem
Quality
Resources
Damage category
Figure 4-12: Comparison of FGD and natural gypsum in wallboard
Using FGD gypsum in place of natural gypsum for wallboard manufacture provides
decreased impacts to human health and ecosystem quality for several reasons, including
the preventing FGD material disposal at the utility and reducing the amount of gypsum
121
that must be mined. These trends would be expected to remain the same if
phosphogypsum was compared with FGD gypsum, although phosphogypsum health
impacts might increase as a function of radiation risk. Resource impacts were only about
20 percent higher for FGD gypsum than for natural gypsum. According to these results,
it is expected that FGD gypsum use in wallboard manufacture would be environmentally
preferable to natural gypsum or phosphogypsum use. This application also represents 82
percent of the total FGD material beneficial use, as it is widely accepted by industry and
regulators (ACAA, 2003). Therefore, the recommended BMP for FGD material is to
produce FGD gypsum for use in wallboard manufacture. FGD material that is not
consumed in this market can be beneficially used in cement and concrete production.
Material extraction. It is difficult to compare material extraction from CCPs with
other extractive processes or products. Materials recovered from CCPs include Al, Fe,
Si, Ga, V, Ni, Mg, Ge, As, Cd, and Zn (Demir et al., 1999; Gutiérrez et al., 1997; Iyer
and Scott, 2001). Metal extraction methods involve thermal or chemical treatment of
CCPs and other fossil fuel combustion products, especially oil combustion ash. Oil ash
produced in Florida has been used by the U.S. Vanadium Corporation to extract metals
that are used in steel, titanium, and chemical applications. Extracting metals from CCPs
and other fossil fuel combustion products presents an opportunity to obtain metals
without added environmental impacts from mining these metals or extracting them from
virgin raw materials. Metals extraction can render the CCPs with lower metals content
and, therefore, safer for disposal or beneficial use, if the CCP composition or
characteristics have not been altered too significantly in the extraction process.
122
However, these thermal or chemical processes can also create a pollutant transfer
problem, where contaminants in the ash are just transferred into another media, such as
water or air, where they must then be treated and disposed. Extractive processes can also
create large amounts of wastewater that must also be treated. Therefore, materials
recovery is recommended as a beneficial use practice contingent on the prevention of
pollutant transfer and the minimization of downstream process waste. This beneficial use
is best where metals can be extracted and used and the remaining CCP can be safely
disposed or, preferably, used in another application
Mine filling and reclamation. Fly ash, bottom ash, and FGD material have been
used in some states to fill abandoned coal mines and to treat acid mine drainage. This
beneficial use is not embraced by regulators and has not been shown to be
environmentally benign or favorable. Furthermore, the closest active coal mine is at least
300 miles away from any Florida utility, making transportation impacts and costs
prohibitive for this application, as discussed previously. It is therefore recommended that
no CCPs generated in Florida be used for mine filling and reclamation activities.
CCP Disposal BMPs
Although it has been demonstrated that CCP beneficial use is environmentally
preferable over disposal, not all CCPs will be able to be used because of quality and cost
limitations. It is inevitable that CCP disposal will continue to be required, and therefore,
CCP BMPs must be included to ensure that the most environmentally auspicious disposal
practices are followed. Recommended BMPs for each stage of the CCP disposal life
cycle are discussed below.
123
Storage and handling
Storage and handling considerations for CCP disposal are similar to those required
for CCP beneficial use. A discussion has been presented previously outlining that dry
storage creates less environmental impacts than wet storage. The same result is
applicable to CCP disposal practices. It must be noted, however, that CCPs are not
usually stored in a dry system and then moved to an impoundment for disposal or vice
versa. The exceptions to this trend occur when CCPs that are being stored for beneficial
use cannot be used because of poor quality or reduced demand and then must be
transferred for disposal. Except for this situation, the recommended storage and handling
practice is to store CCPs in the same way that they will be disposed, i.e., use ash silos and
other dry storage systems for CCPs that are to be landfilled with minimum water content
and use ash ponds for CCPs that are intended for disposal or long-term storage in a
surface impoundment.
Treatment and fixation
As discussed previously, CCPs can be used together and with other products to
create a fixated or stabilized product that is disposed at the utility. The fixation of FGD
sludge with fly ash and bottom ash to form Pozz-o-tec material at the McIntosh facility is
an example of this practice. This example is also the most common kind of CCP
treatment at utilities and is recommended as a BMP for CCPs that are not being used in
any significant amount for a beneficial application. The disadvantage to CCP treatment
is that the product is not likely to be suitable for harvesting and use if a beneficial use
market emerges in the future. However, the advantages of fixing contaminants and
stabilizing the physical properties of CCPs outweigh the potential limitation on
hypothetical future beneficial use.
124
Disposal by landfill and long-term storage
Landfills have been shown by LCA to have fewer impacts to human health but
higher impacts to ecosystem quality and resource use as compared to surface
impoundments. It would be expected that impacts from landfills would be decreased if a
liner or other containment system were used. This expectation was evaluated by
comparing the life cycle of CCP disposal in landfills with and without a liner, with results
shown in Figure 4-13.
Comparative impacts to damage
categories
100%
90%
80%
70%
60%
50%
Landfill
without liner
40%
30%
Landfill with
liner
20%
10%
0%
Human Health
Ecosystem
Quality
Resources
Damage category
Figure 4-13: Comparison of landfills with and without a liner.
Even including impacts associated with producing a polymer liner, the total
impacts to human health and ecosystem quality were reduced when a liner was used in
the landfill. These results are not surprising, as the primary function of the liner would be
to minimize pollutant transfer from the landfill to surrounding water and soil. Resource
use impacts, however, was not significantly changed with liner use. From these results, it
125
can be concluded that the recommended disposal practice for landfills is to require the
use of a HDPE or other synthetic liner in all new landfill cells. Furthermore, if
management options fall between using a landfill with a liner and a surface impoundment
without a liner, the landfill would be the recommended disposal facility.
Disposal or storage by surface impoundment
In comparison to landfills, surface impoundments have higher human health
impacts but lower ecosystem quality and resource impacts. The life cycle of CCP
disposal in impoundments with and without a liner was performed to determine the effect
of lining the impoundments on their overall environmental impact and its comparison
with landfills. Results of this comparison are presented in Figure 4-14.
Comparative impacts to damage
categories
100%
90%
80%
70%
Impoundment
without liner
60%
50%
Impoundment
with liner
40%
30%
20%
10%
0%
Human Health
Ecosystem
Quality
Resources
Damage category
Figure 4-14: Comparison of surface impoundments with and without a liner.
In this comparison, human health was the only category showing significant
decreases to impacts resulting from liner use. Liner use reduced impacts by
126
approximately 50 percent, making the total impacts from surface impoundments
comparable to those from landfills. Therefore, in comparing a landfill without a liner and
a surface impoundment with a liner, the impoundment would be the more
environmentally preferable option. When using surface impoundments in general, the
recommended best practice is to use a polymer or other high performance liner.
General CCP Management Best Practices
In addition to the specific recommended BMPs detailed here, there are general
practices that can lead to higher beneficial use rates and environmentally conscious
decision making regarding CCPs. Specifically, using a state-specific reporting
mechanism for all CCP generators and publishing guidelines from regulators and industry
on quality and environmental standards are encouraged.
Annual CCP generation reports
To facilitate communication and cooperation between utilities, regulators, industry,
and academia, it is recommended that CCP generators be encouraged to file an annual
report on CCP generation with the Florida Department of Environmental Protection
(FDEP). This report will characterize the type, quantity, beneficial use rate, and disposal
methods for all CCPs generated on an annual basis. Beneficial use reporting could
include the specific uses and markets for each CCP as well as the average market price
and transportation requirements and subsidies. This level of detail would provide a
baseline by which future changes in operating parameters or emissions control regulation
could be measured. This report would also include results of toxicity testing and
chemical characterization of each CCP.
127
CCP beneficial use environmental guidelines
Submission of a CCP generation and characterization report would provide a
mechanism for FDEP to approve different beneficial uses based on broad classification of
CCP chemical and physical characteristics. The Wisconsin Department of Natural
Resources uses a similar model to characterize industrial byproducts into five categories
by the amounts of hazardous compounds they contain. This characterization is certified
after initial testing and reconfirmed on a semi-regular basis (every one to five years).
Byproduct generators are also required to submit an annual report verifying the
generation rate and category of the material being produced. Specific beneficial uses are
approved for each of the five categories of byproducts.
This reporting and approval system provides incentive for CCP generators to
monitor and report CCP characteristics and environmental performance and makes it
easier for these products to be beneficially used. As Florida regulators are at the onset of
rulemaking regarding CCP beneficial use and disposal, it is recommended that a similar
methodology be taken into consideration. Using published environmental guidelines and
approved beneficial uses would create a standardized and mutually beneficial CCP
management system for generators, regulators, and industry.
Conclusions
Beneficial use of CCPs has been compared on a life cycle basis to the use of other
raw materials in a variety of emerging and well-established applications. Results from
these comparisons have shown that the markets currently enjoying the highest beneficial
use rates are also providing the best use options for CCPs on an environmental basis.
The highest levels of environmental benefit are afforded fly and bottom ash, FGD
material, and boiler slag by concrete production, gypsum wallboard manufacture, and
128
roofing granules and blasting grit, respectively. Other beneficial use markets that have
potential for environmental and economic benefits include structural fill, flowable fill,
road construction, waste management, and materials extraction. CCP use in agriculture
and soil amendments has not yet been established as a safe and effective beneficial use
and is not recommended over other well-established applications. CCP beneficial use in
mine filling and reclamation is also not a recommended application for Florida, as there
is great uncertainty about this application and no existing market for coal mine filling in
the state. Regardless of the beneficial use market, environmental impacts are
significantly decreased when the market is located close to the utility and transportation
requirements are minimized
In terms of CCP disposal, surface impoundments and landfills both present
different but potentially significant environmental impacts. For either type of facility, the
use of a liner decreases environmental impacts associated with contaminant leaching.
Recommended best practices for CCP disposal are to select or build a disposal facility
with the best containment system and to manage CCPs to minimize dust emissions and
trace metal excursions from the storage and disposal facility.
CCP beneficial use and disposal practices can also be improved by increased
communication between CCP generators, regulators, industry, and academia. An ideal
example of this communication includes annual reporting by CCP generators on the type
and characterization of all products generated from electric utilities and publication of
beneficial use guidelines and standards based on CCP environmental performance.
CHAPTER 5
SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS
Summary
An LCA was performed for CCPs generated at Florida utilities to determine the
contribution of each life cycle stage to the total environmental impact and to compare
CCP beneficial use and disposal options. The four life cycle stages considered were coal
mining and preparation, coal combustion, CCP beneficial use, and CCP disposal. The
LCA was performed according to ISO 14040 standards and included scoping and goal
definition, inventory analysis, impact assessment, and interpretation. Impact assessment
was performed using three published impact methods: Eco-indicator 99, CML, and EDIP.
The LCA was also used to compare different scenarios and to create best management
practices for CCP beneficial use and disposal.
Conclusions
Results from the inventory analysis have shown that raw material demand is
highest for the coal mining and preparation stages. Coal mining and preparation and coal
combustion produce the largest amounts of emissions to air. Emissions to water are
highest from coal combustion and CCP disposal stages. CCP disposal accounted for the
majority of all emissions to soil. The stage of CCP beneficial use had negligible raw
material inputs or environmental emissions compared to the other stages. In fact, in
many cases, beneficial use of CCPs actually prevented emission from being produced.
However, this assessment neglected any potential emissions from the use and disposal of
products or applications that use CCPs as a raw material.
129
130
The impact assessment methods used showed variation based on the categories
chosen and the classification of different emissions into each category. However, the
different methods all illustrated that the stages of coal mining and preparation, coal
combustion, and CCP disposal produced the highest impacts to categories of human
health, ecosystem quality, and resource use. Contrastingly, the beneficial use stage had
minimal impacts or prevented impacts to each damage category. Sensitivity analysis was
performed on the results to determine the life cycle parameters that had the greatest effect
on the total LCA results. These parameters include the type of transportation used to
carry coal to the utility, the total electricity generated, the production of FGD material, or
lack thereof, and the use of liner systems in CCP landfills and surface impoundments.
In comparing CCP end-of-life options, it was shown that environmental impacts
decrease significantly with higher levels of beneficial use. However, impacts were
shown to increase with increasing distance that the CCPs have to be transported from the
utility to their beneficial use, and, therefore, beneficial uses have must be limited to
within a radius of about 200 miles from the utility. Ideally, CCPs would be beneficially
used at a facility located adjacent to the electric utility, similar to eco-industrial parks
espoused by the concepts of industrial ecology. The beneficial use applications showing
the best opportunities for CCP use and lowest environmental impacts included cement
and concrete production, structural and flowable fill, FGD gypsum wallboard
manufacture, roofing granule and blasting grit production, waste management, and
material extraction. Agricultural applications, such as soil amendment, and mine filling
and reclamation are not recommended from a beneficial use perspective.
131
Where CCPs must be disposed, the impacts of using a landfill as opposed to a
surface impoundment depend on the damage category considered, as landfills have higher
impact to ecosystem quality and resource use, but surface impoundments have higher
impact to human health. In any case, it was shown that the environmental impacts would
be significantly decreased by use of liner in the disposal facility.
Recommendations
The most significant limitations to this study were the lack of collected data on the
actual emissions to environmental compartments from different types of disposal
facilities and the inability to consider end-of-life environmental impacts associated with
the products in which CCPs are used. It is recommended that subsequent studies be
conducted to assess the contaminant mobility and emissions from lined and unlined
landfills and surface impoundments. It is also suggested that supplementary LCAs with
more narrow scopes be performed on each beneficial use under consideration. These
LCAs should not only consider the impacts associated with substituting CCPs for other
raw materials in the products produced from a beneficial application, but also the impacts
associated with the product use, reuse, and disposal.
APPENDIX A
REGULATORY STATUS OF CCPS IN EACH STATE
Table A-1: Matrix of state regulations on CCP disposal and beneficial use
Ex.=Exempt;
Cond. Ex.= Conditionally Exempt
Regulations on Beneficial Use
Hazardous
Cond. Ex.
Alaska
Ex.
Arizona Arkansas
Ex.
Ex.
State
California Colorado Connecticut Delaware Florida Georgia
X
Solid
Ex.
Ex.
X
X
Industrial
Use
Specifically
Authorized
Use Not
Specifically
Authorized
Use Allowed
Case-by-Case
Use Allowed as
Generic Waste
Reuse
Use Allowed Specific
Applications
Cement/
Concrete
Ex.
X
X
X
X
X
Ex.
X
X
Industrial Solid
Special
Ex.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Structural Fill
Landfill Cover
X
Mine Filling
Approved Applications
Regulatory Classifications
Alabama
Waste Treat/
Stabilization
Soil/ Land/
Agriculture
Road Base or
Subbase
Gypsum
Product/
Wallboard
Material
Recovery
Construction/
Engineered
Structures
X
X
X
X
X
X
X
Other
132
X
133
Table A-1. Continued
Ex.=Exempt;
Cond. Ex.= Conditionally Exempt
Regulations on Beneficial Use
Hazardous
Ex
Idaho
Illinois
Ex.
Ex.
Cond. Ex.
Iowa
Ex.
State
Kansas
Ex.
Kentucky
Ex.
X
Industrial Solid
X
Construction/
Engineered
Structures
Other
Ex.
Maine Maryland
Cond.
Ex.
Ex.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Landfill Cover
Mine Filling
Waste Treat/
Stabilization
Soil/ Land/
Agriculture
Road Base or
Subbase
Gypsum
Product/
Wallboard
Material
Recovery
Louisiana
X
Industrial
Special
Use
Specifically
Authorized
Use Not
Specifically
Authorized
Use Allowed
Case-by-Case
Use Allowed as
Generic Waste
Reuse
Use Allowed Specific
Applications
Cement/
Concrete
Indiana
Cond. Ex.
Solid
Structural Fill
Approved Applications
Regulatory Classifications
Hawaii
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
134
Table A-1. Continued
State
Ex.=Exempt;
Cond. Ex.= Conditionally Exempt
Regulations on Beneficial Use
Hazardous
Solid
Ex.
Michigan
Ex.
Minnesota
Ex.
Cond. Ex.
Ex.
Nebraska
Ex.
Nevada
Ex.
New
Hampshire
Ex.
New
Jersey
Ex.
Cond.
Ex.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Construction/
Engineered
Structures
Other
Montana
X
Landfill Cover
Mine Filling
Waste Treat/
Stabilization
Soil/ Land/
Agriculture
Road Base or
Subbase
Gypsum
Product/
Wallboard
Material
Recovery
Ex.
Missouri
Cond. Ex.
Industrial Solid
Special
Use
Specifically
Authorized
Use Not
Specifically
Authorized
Use Allowed
Case-by-Case
Use Allowed as
Generic Waste
Reuse
Use Allowed Specific
Applications
Cement/
Concrete
Mississippi
Cond. Ex.
Industrial
Structural Fill
Approved Applications
Regulatory Classifications
Massachusetts
X
X
X
X
135
Table A-1. Continued
State
Ex.=Exempt;
Cond. Ex.= Conditionally Exempt
Regulations on Beneficial Use
Hazardous
Ex.
Solid
Ex.
New
York
Ex.
North
North
Carolina Dakota
Ex.
Ex.
Ohio
Ex.
Oklahoma Oregon
Ex.
Ex.
Ex.
Rhode
Pennsylvania Island
Ex.
X
N/A - No coal
fired power
plants in
Rhode Island
South
Carolina
Ex.
Industrial
Industrial Solid
X
X
Special
Use
Specifically
Authorized
Use Not
Specifically
Authorized
Use Allowed
Case-by-Case
Use Allowed as
Generic Waste
Reuse
Use Allowed Specific
Applications
Cement/
Concrete
Structural Fill
Approved Applications
Regulatory Classifications
New
Mexico
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Landfill Cover
X
X
Mine Filling
X
X
Waste Treat/
Stabilization
Soil/ Land/
Agriculture
Road Base or
Subbase
Gypsum
Product/
Wallboard
Material
Recovery
Construction/
Engineered
Structures
Other
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
136
Table A-1. Continued
State
Ex.=Exempt;
Cond. Ex.= Conditionally Exempt
Regulations on Beneficial Use
Hazardous
Ex.
Solid
X
Tennessee Texas
Cond. Ex.
Ex.
Utah
Ex.
Vermont Virginia
Ex.
Cond.
Ex.
West
Washington Virginia
Ex.
Cond. Ex.
Cond.
Ex.
X
Ex.
Industrial
Wisconsin Wyoming
Ex.
Ex.
X
Industrial Solid
X
X
Special
Use
Specifically
Authorized
Use Not
Specifically
Authorized
Use Allowed
Case-by-Case
Use Allowed as
Generic Waste
Reuse
Use Allowed Specific
Applications
Cement/
Concrete
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Landfill Cover
Mine Filling
Other
X
X
X
X
X
X
X
X
X
X
X
X
Waste Treat/
Stabilization
Soil/ Land/
Agriculture
Road Base or
Subbase
Gypsum
Product/
Wallboard
Material
Recovery
Construction/
Engineered
Structures
X
X
Structural Fill
Approved Applications
Regulatory Classifications
South
Dakota
X
X
X
X
X
X
X
X
X
X
X
APPENDIX B
DATA COLLECTION SURVEYS AND QUESTIONNAIRES
Site Visit Questionnaire
The site visit questionnaire was given to environmental managers at the four
Florida utilities visited as part of this research project. This questionnaire provided the
framework for interviewing the site contacts and collecting utility-specific operating
information.
Utility Site
1.
2.
3.
4.
What is the average electricity generation at this site?
What is the average fuel mix used at this site?
How does the fuel mix vary on a monthly or yearly basis?
What is the average electricity generation per each of the fuel sources?
Raw Material
1.
What are the primary sources for coal used at this site?
2.
3.
How is the coal transported to the site?
How is transported within the site?
4.
How is the coal stored?
5.
What is the average amount of coal stored on site?
6.
What is the average yearly and monthly use of coal?
7.
What are the ultimate and proximate analyses of coal quality?
8.
Are the following parameters known? If so, what are their average values for the
predominant coal source?
9.
Rank and group:
10.
Moisture content:
11.
Carbon content:
12.
Ash content:
13.
Sulfur content:
14.
Hydrogen content:
137
138
15.
Chlorine content:
16.
Oxygen content:
17.
Ignition temperature:
18.
Calorific Value:
19.
What methods are used to prepare the coal for combustion?
Combustion Parameters
1.
What type of furnace/boiler is used for combustion?
2.
What is the coal feed rate to the boiler, on an average, maximum, and per MWhr
produced basis?
3.
What is the average air-to-fuel ratio entering the boiler?
4.
To what fineness or degree is the coal pulverized?
5.
Are any pre-combustion dust or coal fines control methods used?
6.
At what temperatures is combustion initiated and maintained?
7.
What is the average retention time in the boiler?
8.
How are coal particles and air mixed within the boiler?
9.
What measurement and control systems are used for monitoring combustion
performance?
10.
What is the average carbon carryover or loss on ignition?
11.
Is an air preheater or water preheater used?
12.
What is the boiler water feed rate (recycled + makeup):
13.
What is the boiler water makeup rate?
Air emissions control
1.
2.
3.
4.
5.
What is the average flow rate through (each) AEC device?
What types of post combustion air emissions control (AEC) devices are used?
What AEC device operating parameters are measured?
What are the measured AEC device efficiencies?
What type of system is used for flue gas desulfurization?
139
6.
7.
8.
9.
What type and amount of sorbent is used?
What other types and amounts of additional materials are used?
What is the total flow rate of (post AEC) flue gas?
What is the chemical composition of the total (post AEC) flue gas?
CCP (high volume) Generation and Management
1.
What is the average chemical composition of each CCP produced?
2.
What is the average production rate of each type of CCP?
3.
What are the handling methods used for each CCP?
4.
How are each of the CCPs transported on site?
5.
What are the storage methods for each CCP?
6.
What is the average CCP generation per each fuel type?
7.
Are coal and oil wastes co-managed or separately handled, stored, transported?
8.
Are any CCPs comanaged with low volume products?
9.
What is the total amount CCPs applied to land (via landfill)?
10.
What is the chemical composition of CCPs applied to land (landfill)?
11.
What are the physical characteristics of CCPs applied to land (landfill)?
12.
What is the total amount of CCPs applied to land (via surface impoundment)?
13.
What is the chemical composition of CCPs applied to land (surface impoundment)?
14.
What are the physical characteristics of CCPs applied to land (surface
impoundment)?
15.
In what manner are all other (low volume product) solid emissions managed?
16.
What is the total amount of low volume product applied to land?
17.
What is the chemical composition of low volume product applied to land?
18.
What are the physical properties of low volume product applied to land?
19.
What type of containment systems are used for high and low volume CCPs that are
land applied?
20.
For a landfill: What type of base material is used?
140
21.
For a landfill: What type, size, permeability, and material are the landfill liners?
22.
For a landfill: What methods are used for landfill cover?
23.
For a landfill: How is landfill leachate and runoff controlled?
24.
For a landfill: What type, if any, of landfill gas control systems are used?
25.
For a landfill: What are the landfill closure procedures?
26.
For surface impoundments: What size, type, and capacity are used?
27.
For surface impoundments: Where are they located?
28.
For surface impoundments: Are they lined, and if so, what type, size, permeability,
and material are the liners?
29.
For surface impoundments: What type of discharge system is used?
30.
How are high and low volume CCPs applied to land monitored?
31.
Are groundwater monitoring wells used?
32.
If so, where are the wells located in relation to land application sites?
33.
What chemical parameters are monitored in the wells?
34.
What are the groundwater flow direction and characteristics at the utility site?
35.
What are the average monitoring results?
36.
Are any tests performed on CCPs before they are applied to land?
37.
Are toxicity characteristic testing procedures performed on a regular or other basis?
38.
If so, what are the average results for CCPs?
Ancillary Operations
1.
In terms of other ancillary operations, what major process streams come into
contact directly with the source coal or the CCPs or indirectly with the equipment
being used for coal combustion and CCP storage, handling, and transportation?
2.
What are the chemical compositions of each of these streams?
3.
What is the physical makeup of each of these streams?
4.
What are the average flow rates of each of these streams?
141
5.
What is the source of each of these streams?
6.
How are each of these streams handled and treated?
7.
How are each of these streams disposed?
CCP Beneficial Use
1.
What are the existing methods for beneficial use of each CCP at this site (use on
site or sale to outside market)?
2.
What quantities of each CCP are used in each of these beneficial use methods?
3.
Is treatment or beneficiation (e.g., stabilization, fixation, gypsum production)
performed on any of the CCPs used or sold for beneficial use?
4.
If so, what methods are used and what quantity of CCP is processed in each
treatment?
5.
What are the primary markets or end users for off-site beneficial use of CCPs from
this site?
6.
Are any tests or quality assurance evaluations performed on CCPs designated for
beneficial use?
7.
If so, what is performed and what are the average results?
8.
How are CCPs designated for beneficial use handled and transported on site?
9.
How are these CCPs handled and transported to outside markets?
Utility Follow-up Survey
The follow-up survey was administered by mail to the coal-fired power plants in
Florida that were not visited during the project. The survey was also given to all the oilfired utilities in Florida with the request that they provide information about the
generation, beneficial use, and disposal of any combustion products from oil combustion.
This study is being conducted as part of a research project with the Florida
Department of Environmental Protection and the Florida Electric Coordinating Group.
The purpose of this study is to verify initial research findings on coal combustion
142
processes and products in the State of Florida. Participation in this survey is completely
voluntary, and there is no penalty for not participating. You have the right to withdraw at
any time without consequence.
To participate, please complete the following questions about operating parameters,
environmental impacts, and combustion product disposal and beneficial use at your
facility. Please report any responses based on normal operating conditions with average
annual values.
Utility information
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Utility site location:
What is the average electricity generation (MWh) at this site on a yearly basis?
What is the average annual fuel mix (%) used at this site?
What are the primary sources for coal used at this site?
How is the coal transported to the site?
What is the average yearly use (tons) of coal?
What type of furnace/boiler is used for combustion?
To what fineness or degree is the coal pulverized?
What is the average carbon carryover or loss on ignition?
Is an air preheater, water preheater, or both used?
Air emissions control
1.
2.
3.
4.
What types of post combustion air emissions control (AEC) devices are used?
What are the measured AEC device efficiencies?
What type of system is used for flue gas desulfurization?
What type and amount of sorbent are used?
CCP (high volume) Generation and Management
1.
What is the average annual production rate (tons/year) of each type of CCP?
2.
Fly ash:
3.
Bottom ash:
4.
Boiler slag:
5.
FGD material:
6. Are coal and oil wastes co-managed or separately handled, stored, transported?
143
7. Are any CCPs comanaged with low volume products?
8. What is the total amount (tons/year) of CCPs applied to land (via landfill)?
9. Fly ash:
10. Bottom ash:
11. Boiler slag:
12. FGD material:
13. What is the total amount (tons/year) of CCPs applied to land (via surface
impoundment)?
14. Fly ash:
15. Bottom ash:
16. Boiler slag:
17. FGD material:
18. Properties of containment systems for land applied CCPs:
19. What is the total landfill capacity (acreage and height)?
20. What type of liner, if any, is used (if no liner, write “none”)?
21. What type of cover, if any is used (if no cover, write “none”)?
22. What are the landfill closure procedures?
23. How large is the total surface impoundment capacity (volume)?
24. What type of liner, if any, is used (if no liner, write “none”)?
CCP Beneficial Use
1.
2.
3.
4.
5.
6.
What is the average annual amount of CCPs used or sold for beneficial use
(tons/yr)?
Fly ash:
Bottom ash:
Boiler slag:
FGD material:
Please check all markets for which each type of CCP is used or sold:
144
Table B-1: Utility follow-up survey table of CCP markets
Bottom
Application
Fly Ash
Ash
Cement production
Aggregate
Structural or flowable fill
Other construction use not listed
here
Wallboard manufacture
Agriculture or other land
application
Landfill cover
Waste treatment or stabilization
Material recovery
Road base or sub-base
Other (please list)
Other (please list)
Boiler
Slag
FGD
Material
7. What methods of treatment or beneficiation (e.g., stabilization, fixation, gypsum
production) are performed on the CCPs used or sold for beneficial use (if none
used, write “none”)?
8. Fly ash:
9. Bottom ash:
10. Boiler slag:
11 FGD material:
12. Which entity is responsible for costs of transporting CCPs to outside markets
(utility site or outside market)?
13. What quality assurance measures or tests are performed on the CCPs used or sold
for beneficial use applications (if none performed, write “none”):
14.
Fly ash:
15.
Bottom ash:
16.
Boiler slag:
17.
FGD material:
18. If beneficial use is not ongoing to the greatest extent desired for some or all of the
CCPs generated at this site, please identify the factors that limit CCP beneficial use.
145
Please check the box in each row below that most accurately describes the effect of
each limiting factor.
Table B-2: Utility follow-up survey table of factors affecting CCP beneficial use
Strongly limits
Somewhat
Factor
Does not
beneficial use
limits
limit
beneficial use beneficial use
Cost of CCP transportation
Regulations or permitting
High or variable LOI
Quality parameters (other than
LOI)
Lack of beneficial use market
Cost of CCP storage, processing,
or handling
Environmental impacts, if any
Other, please list
Other, please list
CCP Marketers Survey
The marketers survey was administered by mail to contacts in companies identified
by the American Coal Ash Association (ACAA) as being involved with CCP marketing
or beneficial use.
1. Based on annual operations within your company or organization, what is the total
annual amount and average market price for each of the CCPs designated for
beneficial use?
Table B-3: CCP marketer survey table of amounts and market prices for CCPs
Annual use or sale
CCP
Average market price
(tons/yr)
Fly ash
Bottom ash
Boiler slag
FGD material
146
2. In general, which entities (utility, marketer, end user) subsidize the co st of
transporting the CCP from the utility to its market?
3. Please check all of the beneficial use ma rkets for each type of product for which
your company or organization is actively using or marketing CCPs:
Table B-4: CCP marketer survey table on CCP beneficial uses
Beneficial Use
Portland cement
replacement
Mineral admixture for
concrete
Autoclaved aerated
concrete
Aggregate
Grouting
Road base/subbase
Asphaltic pavement
Structural fill
Flowable fill
Soil
amendment/agriculture
Mine reclamation
Metals
recovery/metallurgical
Ashalloys
Filler for
paint/plastic/etc…
Wallboard
manufacture
Blasting grit
Snow or ice control
Roofing granules
Waste_treatment
Other: Specify
Fly ash
Bottom ash
Boiler slag
FGD material
147
4. How does cost and financial responsibility for transportation vary with type of
beneficial use and quality of the CCP? For instance, would a utility be more likely
responsible for transport costs if they were selling a high LOI fly ash to cement
industry than if they were selling a low LOI ash?
5. Please check the box in each row below that most accurately describes the effect of
each limiting factor on CCP beneficial use, with respect to your company or
organization:
Table B-5: CCP marketer survey table on factors affecting CCP beneficial use
Somewhat
Does not
Strongly limits
limits beneficial
Factor
limit
beneficial use
use
beneficial use
Regulations or permitting
High or variable LOI
Quality parameters (other than LOI)
Cost of CCP transportation
Relative low cost of competing
materials
Lack of beneficial use market
Environmental impacts, if any
Cost of CCP storage, processing, or
handling
Other, please specify
6. What are the most important physical and chemical properties of a CCP that
determine its use and/or value for a specific beneficial use market?
7. Please provide any additional comments regarding economics, applications, or
limitations of CCP beneficial use that you feel may be valuable to this and future
research:
8. Please indicate “yes” if you would allow us to use your company name or
information in subsequent reports or presentations. Please check “no” if you would
like us to keep your information confidential: Yes ______ No ______
APPENDIX C
COLLECTED DATA
Table C-1: Data collected on coal mining and preparation
Unit
Coal source
Mining method
Crist-Pensacola (I)
Crist-Pensacola (II)
Big Bend-Tampa
Illinois Basin
Columbian
Illinois Basin
Surface/Underground
Surface/Underground
Surface/Underground
279.46
279.46
597.73
25.00
25.00
25.00
Total coal to preparation
tons/hr
Distance to coal preparation
miles
Transportation to coal preparation
type
Truck
Truck
Truck
Cleaning method
type
Jigging and froth flotation
Jigging and froth flotation
Jigging and froth flotation
Amount cleaned
tons/hr
279.46
279.46
597.73
Cleaning accepts to utility
tons/hr
209.60
209.60
448.30
Cleaning rejects
tons/hr
69.87
69.87
149.43
Energy input to preparation
KWhr
Raw materials used for preparation
type
Water
Water
Water
Distance to utility
miles
840
1640
1100
---
---
---
Coal Quality on an as-received basis
Coal class
Coal group
Bituminous
Bituminous
Bituminous
High volatile C
High volatile C
High volatile C
Coal moisture content high
wt %
11.98
13.42
14.00
Coal moisture content low
wt %
9.99
10.67
7.00
Coal carbon content high
wt %
71.54
69.24
75.00
Coal carbon content low
wt %
66.41
66.59
60.00
Coal ash content high
wt %
7.46
6.00
9.50
Coal ash content low
wt %
5.90
3.97
9.00
Coal sulfur content high
wt %
1.61
0.67
3.50
Coal sulfur content low
wt %
0.94
0.60
1.50
Coal hydrogen content high
wt %
4.58
4.55
5.00
Coal hydrogen content low
wt %
4.17
4.38
4.20
Coal chlorine content high
wt %
0.00
0.00
0.40
Coal chlorine content low
wt %
0.00
0.00
0.02
Coal oxygen content high
wt %
7.55
7.56
9.00
Coal oxygen content low
wt %
4.55
0.00
6.00
Coal calorific value high
BTU/lb
12,207
11,701
13,500
Coal calorific value low
BTU/lb
11,830
11,663
10,800
148
149
Table C-1. Continued
Unit
Coal source
Mining method
Lakeland
Crystal River
James River, Kentucky
West Virginia, Kentucky
Surface/Underground
Surface/Underground
Total coal to preparation
tons/hr
166.20
1,528.00
Distance to coal preparation
miles
25.00
25.00
Transportation to coal preparation
type
Truck
Truck
Cleaning method
type
Jigging and froth flotation
Jigging and froth flotation
Amount cleaned
tons/hr
166.20
1,528.00
Cleaning accepts to utility
tons/hr
124.65
1,146.00
Cleaning rejects
tons/hr
41.55
382.00
Energy input to preparation
KWhr
Raw materials used for preparation
type
Water
Water
Distance to utility
miles
800
800
---
---
Bituminous
Bituminous
High volatile C
High volatile C
Coal Quality on an as-received basis
Coal class
Coal group
Coal moisture content high
wt %
8.32
10.00
Coal moisture content low
wt %
4.35
8.00
Coal carbon content high
wt %
75.89
75.00
Coal carbon content low
wt %
74.95
70.00
Coal ash content high
wt %
11.17
10.00
Coal ash content low
wt %
7.22
8.00
Coal sulfur content high
wt %
1.59
1.00
Coal sulfur content low
wt %
1.50
0.60
Coal hydrogen content high
wt %
4.68
5.00
Coal hydrogen content low
wt %
4.30
5.00
Coal chlorine content high
wt %
0.06
0.12
Coal chlorine content low
wt %
0.04
0.12
Coal oxygen content high
wt %
8.97
5.00
Coal oxygen content low
wt %
6.57
4.00
Coal calorific value high
BTU/lb
13,693
13,000
Coal calorific value low
BTU/lb
13,466
11,700
150
Table C-2: Data collected on coal combustion
Unit
Coal Transport to Site
type
Coal % of total fuel mix
%
Long-term coal storage
type
Short-term coal storage
type
Average amt coal stored on site
days
Total annual coal usage
tons/year
Crist-Pensacola
Big Bend-Tampa
Barge
Barge
94
100
Open coal pile
Open coal pile
Blending bins, day bunkers
25
30
2,000,000
3,219,672
170,000
268,306
419.2
Pulverizer
448.3
Crusher/dryer; 9-ball mills; 5bowl mills
200
200
Average monthly coal usage
tons/month
Coal feed to process
tons/hr
Crushing/pulverization methods
type
Sieve size
# mesh
Percent through sieve
%
70
70
Pulverizer rejects
tons/hr
2.2
2.3
Coal feed
tons/hr
417
Furnace Type (I)
type
Furnace Type (II)
type
Net MW
MW
Coal feed per net coal MWhr
tons/MWhr
Mixing methods
type
Air-to-Fuel ratio
mass:mass
446
Riley wall-fired wet bottom (3:1Wall fired dry bottom
3)
CE Tangentially-fired dry bottom
Tangentially fired dry bottom
(1:4)
980
1125
0.43
0.40
Primary and secondary Primary and secondary preheated
preheated air
air
1.8:1
1.1:1
Total air feed rate (per MWhr)
tons/hr
751
803
Combustion Temperature
deg F
2300
3000
Furnace retention time
sec
Average LOI range (high)
%
Average LOI range (low)
%
8.0
4.0
Boiler water feed rate
gpd
19,268,697
8,630,000
Boiler water makeup rate
gpd
108,000
500,000
AEC device
type
ESP
ESP
Total flow rate through AEC
acfm
AEC efficiency
%
FGD system
3
2.5
15.0
14.0
1,700,000
99
99
type
None
Limestone forced oxidation
Sorbent type
type
N/A
Limestone
Sorbent amount
tons/day
0
1095.9
N/A
Dibasic acid
Additional materials
type
Additional material amount
tons/day
Total exhaust flow rate
acfm
Exhaust NOx
tons/hr
Exhaust SO2
tons/hr
1.96
0.62
Exhaust CO2
tons/hr
236.36
431.63
Exhaust PM
tons/hr
FA Produced
tons/year
144,000
267,250
BA Produced
tons/year
16,000
21,819
Slag Produced
tons/year
0
77,132
FGD Produced
tons/year
0
819,261
Total CCP Produced
tons/year
160,000
1,185,461
0
5.5
1,700,000
0.42
1.50
151
Table C-2. Continued.
Unit
Coal Transport to Site
type
Coal % of total fuel mix
%
Long-term coal storage
Lakeland
Crystal River
Barge, Rail, Truck
Barge, Rail
90
100
type
Open compacted piles
Open coal pile
Short-term coal storage
type
Open loose active piles
Average amt coal stored on site
days
Total annual coal usage
tons/year
48
35
900,857
8,208,000
Average monthly coal usage
tons/month
75,071
684,000
Coal feed to process
Crushing/pulverization methods
tons/hr
type
124.7
Crusher/dryer; Pulverizer
1146.0
Crusher; Pulverizer
Sieve size
# mesh
200
200
Percent through sieve
%
74
70
Pulverizer rejects
tons/hr
0.7
6.0
Coal feed
tons/hr
Furnace Type (I)
type
124
Balanced draft, Carolina-type
radiant dry bottom
1140
Balanced draft, opposed-firing,
dry bottom
Balanced draft, tangentially-fired,
dry bottom
340
2430
Furnace Type (II)
type
Net MW
MW
Coal feed per net coal MWhr
tons/MWhr
Mixing methods
type
Air-to-Fuel ratio
mass:mass
Total air feed rate (per MWhr)
Combustion Temperature
Furnace retention time
sec
Average LOI range (high)
Average LOI range (low)
Boiler water feed rate
gpd
Boiler water makeup rate
AEC device
0.36
0.47
Primary and secondary Primary and secondary preheated
preheated air
air
9:01
11:1
tons/hr
223
2052
deg F
1600
2800
4
3
%
5.8
8.9
%
4.0
4.5
7,189,813
23,007,400
gpd
0
230,074
type
ESP
ESP
Total flow rate through AEC
acfm
1,500,000
AEC efficiency
%
99
99
FGD system
type
Wet Limestone Scrubber
None
Lime sludge from WT plant
N/A
Sorbent type
type
Sorbent amount
tons/day
Additional materials
type
Additional material amount
tons/day
Total exhaust flow rate
acfm
16.52
0
Grind limestone
N/A
1.04
0
1,500,000
Exhaust NOx
tons/hr
0.33
Exhaust SO2
tons/hr
0.69
1.05
3.08
Exhaust CO2
tons/hr
221.49
499.20
Exhaust PM
tons/hr
0.01
0.30
FA Produced
tons/year
80,918
505,000
BA Produced
tons/year
12,250
50,000
Slag Produced
tons/year
0
0
FGD Produced
tons/year
160,826
0
Total CCP Produced
tons/year
253,994
555,000
152
Table C-3: Data collected on CCP Beneficial Use
Unit
Crist-Pensacola
Big Bend-Tampa
FA storage method
type
Above-ground silo
Above-ground silo
FA handling
type
Pneumatic conveyor
Pneumatic conveyor
BA storage method
type
Above-ground hydrobin
Lined settling pond
BA handling
type
Wet sluiced
Wet sluiced
Slag storage method
type
n/a
Settling pond
Slag handling
type
n/a
Wet sluiced
FGD storage method
type
n/a
Stack out pile
FGD handling
type
n/a
Open conveyor
FA Beneficial Use
type
Cement industry
Cement industry
BA Beneficial Use
type
Cement industry
Cement industry
Slag Beneficial Use
type
n/a
Aggregate and blasting grit
FGD Beneficial Use
type
n/a
National Gypsum/wallboard
CCP Beneficiated
type
None
FGD material
Beneficiation method
type
None
Gypsum production
Total amount FA Sold
tons/year
119,000
291,834
Harvested FA Sold
tons/year
0
25,634
82.6%
99.6%
% FA Sold
Total amount BA Sold
tons/year
0
33,820
Harvested BA Sold
tons/year
0
12,001
0.0%
100.0%
0
67,147
0.0%
87.1%
0
757,601
0.0%
92.5%
119,001
1,188,039
% BA sold
Amount Slag Sold
tons/year
% BA sold
Amount FGD Sold
tons/year
% FGD sold
Total CCP beneficial use tons/year
153
Table C-3. Continued
Unit
Lakeland
Crystal River
FA storage method
type
Above-ground silo
Above-ground silo
FA handling
type
Pneumatic, screw conveyor
Pneumatic conveyor
BA storage method
type
Above-ground silo
Above-ground silo
BA handling
type
Hydromantic conveyor
Pneumatic conveyor
Slag storage method
type
n/a
n/a
Slag handling
type
n/a
n/a
FGD storage method
type
Storage tank
n/a
FGD handling
type
Pump, conveyor
n/a
FA Beneficial Use
type
None
Cement industry
BA Beneficial Use
type
None
Cement industry
Slag Beneficial Use
type
None
n/a
FGD Beneficial Use
type
None
n/a
CCP Beneficiated
type
FA, BA, FGD material
FA, BA
Beneficiation method
type
Pozz-o-tec production
Aardelite production
Total amount FA Sold
tons/year
0
478,000
Harvested FA Sold
tons/year
0
1,000
0.0%
94.5%
% FA Sold
Total amount BA Sold
tons/year
0
23,000
Harvested BA Sold
tons/year
0
1,000
0.0%
44.0%
0
0
0.0%
0.0%
0
0
0.0%
0.0%
0
503,001
% BA sold
Amount Slag Sold
tons/year
% BA sold
Amount FGD Sold
tons/year
% FGD Sold
Total CCP beneficial use tons/year
154
Table C-4: Data collected on CCP Disposal
Unit
Crist-Pensacola
Big Bend-Tampa
FA handling
dry/wet
Dry
Wet
Amount FA landfilled
Amount FA to surface
impoundment
tons/yr
25,000
0
tons/yr
0
1,049
BA handling
dry/wet
Wet
Wet
Amount BA landfilled
Amount BA to surface
impoundment
tons/yr
12,800
0
tons/yr
3200
0
Amount BS landfilled
Amount BS to surface
impoundment
tons/yr
0
0
tons/yr
0
9,985
Amount FGD stockpiled
tons/yr
0
61,660
Landfill liner
type
Bottom ash
None
Landfill cover on closure
type
Clay, topsoil, grasses
Surface impoundment liner
type
Discharge to surface water?
Comanagement with oil
wastes?
Comanagement with low
volume wastes?
Yes/No
N/A
To stormwater collection
pond, permeate to SW
Soil and vegetation
HDPE for FA,BA ponds;
None for slag ponds
Yes/No
No
Yes/No
No
No
Only off-spec CCPs for
disposal
type
Groundwater wells
surrounding landfill
Groundwater wells
surrounding impoundments
Monitoring method
None
155
Table C-4. Continued.
Unit
Lakeland
Crystal River
FA handling
dry/wet
Wet
Dry
Amount FA landfilled
Amount FA to surface
impoundment
tons/yr
80,918
28,000
tons/yr
0
0
BA handling
dry/wet
Wet
Dry
Amount BA landfilled
Amount BA to surface
impoundment
tons/yr
12,250
28,000
tons/yr
0
0
Amount BS landfilled
Amount BS to surface
impoundment
tons/yr
0
0
tons/yr
0
0
Amount FGD stockpiled
tons/yr
160,826
0
Landfill liner
type
Pozz-o-tec material
None
Landfill cover on closure
Surface impoundment liner
type
type
Cover soil, grass
N/A
Discharge to surface water?
Comanagement with oil
wastes?
Comanagement with low
volume wastes?
Yes/No
Monitoring method
Soil and vegetation
N/A
Only from overflow or storm
None
surge
Yes/No
No
No
Yes/No
No
Groundwater wells
surrounding landfill
No
Groundwater wells
surrounding landfill
type
156
Table C-5: Toxic Release Inventory (TRI) data collected for each utility
Crist-Pensacola
Air
Surface
Water
Air
Surface
Water
5.64E+04
4.62E+00
2.31E-01
1.34E+02
1.24E+05
4.57E+00
0.00E+00
2.95E+02
0.00E+00
0.00E+00
0.00E+00
Land
Land
Arsenic compounds
lbs/yr
1.94E+03
Barium compounds
lbs/yr
1.92E+03
Beryllium compounds
lbs/yr
Chromium compounds
lbs/yr
7.46E+02
3.44E+04
1.78E+00
0.00E+00
8.21E+01
Cobalt compounds
lbs/yr
3.00E+02
1.90E+04
7.16E-01
0.00E+00
4.53E+01
Copper compounds
lbs/yr
4.19E+02
2.94E+04
1.00E+00
5.22E+00
7.01E+01
Dioxin and Dioxin-like compounds
lbs/yr
9.18E-04
2.19E-06
0.00E+00
0.00E+00
Hydrochloric acid
lbs/yr
1.61E+07
3.85E+04
0.00E+00
0.00E+00
Hydrogen fluoride
lbs/yr
9.86E+04
2.35E+02
0.00E+00
0.00E+00
Lead compounds
lbs/yr
3.48E+03
9.80E+01
1.28E+05
8.29E+00
2.34E-01
3.06E+02
Manganese compounds
lbs/yr
8.44E+02
6.00E+00
3.73E+04
2.01E+00
1.43E-02
8.90E+01
Mercury compounds
lbs/yr
2.41E+02
1.72E+02
5.75E-01
0.00E+00
4.09E-01
Molybdenum trioxide
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Nickel compounds
lbs/yr
2.22E+00
1.46E-01
1.52E+02
Polycyclic aromatic compounds
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Selenium compounds
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Sulfuric acid
lbs/yr
3.66E+05
8.73E+02
0.00E+00
0.00E+00
Vanadium compounds
lbs/yr
1.11E+03
6.27E+04
2.64E+00
0.00E+00
1.50E+02
Zinc compounds
lbs/yr
2.79E+03
8.98E+02
1.09E+05
6.65E+00
2.14E+00
2.60E+02
Total
lbs/yr
1.66E+07
3.35E+03
6.64E+05
3.97E+04
7.98E+00
1.58E+03
9.30E+02
9.70E+01
Crist Average per ton coal/hr
2.19E+03
6.10E+01
6.36E+04
157
Table C-5. Continued
Big Bend-Tampa
Air
Surface
Water
Big Bend Average per ton coal/hr
Land
Air
Surface
Water
Land
Arsenic compounds
lbs/yr
7.90E+02
8.00E+02
1.76E+00
0.00E+00
1.78E+00
Barium compounds
lbs/yr
8.50E+02
7.90E+03
1.90E+00
0.00E+00
1.76E+01
Beryllium compounds
lbs/yr
1.20E+02
2.70E+02
2.68E-01
0.00E+00
6.02E-01
Chromium compounds
lbs/yr
1.80E+03
3.50E+03
4.02E+00
0.00E+00
7.81E+00
Cobalt compounds
lbs/yr
4.10E+02
8.60E+02
9.15E-01
0.00E+00
1.92E+00
Copper compounds
lbs/yr
1.40E+02
1.30E+03
3.12E-01
0.00E+00
2.90E+00
Dioxin and Dioxin-like compounds lbs/yr
1.61E-02
3.58E-05
0.00E+00
0.00E+00
Hydrochloric acid
lbs/yr
4.40E+05
9.81E+02
0.00E+00
0.00E+00
Hydrogen fluoride
lbs/yr
3.00E+04
6.69E+01
0.00E+00
0.00E+00
Lead compounds
lbs/yr
2.70E+03
3.30E+03
6.02E+00
0.00E+00
7.36E+00
Manganese compounds
lbs/yr
2.80E+03
2.60E+04
6.25E+00
0.00E+00
5.80E+01
Mercury compounds
lbs/yr
1.80E+02
1.10E+01
4.02E-01
0.00E+00
2.45E-02
Molybdenum trioxide
lbs/yr
1.10E+02
9.80E+02
2.45E-01
0.00E+00
2.19E+00
Nickel compounds
lbs/yr
4.10E+03
9.01E+03
9.15E+00
0.00E+00
2.01E+01
Polycyclic aromatic compounds
lbs/yr
5.40E+00
1.20E-02
0.00E+00
0.00E+00
Selenium compounds
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Sulfuric acid
lbs/yr
8.40E+05
1.87E+03
0.00E+00
0.00E+00
Vanadium compounds
lbs/yr
1.40E+03
1.20E+04
3.12E+00
0.00E+00
2.68E+01
Zinc compounds
lbs/yr
2.50E+03
1.11E+04
2.18E+04
5.58E+00
2.48E+01
4.85E+01
Total
lbs/yr
1.33E+06
1.11E+04
8.77E+04
2.96E+03
2.48E+01
1.96E+02
158
Table C-5. Continued
Lakeland-McIntosh
Air
Surface
Water
Air
Surface
Water
2.99E+04
5.01E+00
2.26E-01
2.41E+02
6.40E+05
8.77E+01
0.00E+00
5.16E+03
0.00E+00
0.00E+00
0.00E+00
3.75E+00
1.37E-01
4.89E+02
0.00E+00
0.00E+00
0.00E+00
6.57E+01
2.14E+00
3.28E+03
Land
Land
Arsenic compounds
lbs/yr
6.21E+02
Barium compounds
lbs/yr
1.09E+04
Beryllium compounds
lbs/yr
Chromium compounds
lbs/yr
Cobalt compounds
lbs/yr
Copper compounds
lbs/yr
8.15E+03
Dioxin and Dioxin-like compounds
lbs/yr
3.31E-03
2.67E-05
0.00E+00
0.00E+00
Hydrochloric acid
lbs/yr
1.23E+05
9.94E+02
0.00E+00
0.00E+00
Hydrogen fluoride
lbs/yr
1.89E+04
1.52E+02
0.00E+00
0.00E+00
Lead compounds
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Manganese compounds
lbs/yr
6.51E+02
1.15E+05
5.25E+00
0.00E+00
9.26E+02
Mercury compounds
lbs/yr
2.00E+02
4.54E+02
1.61E+00
2.42E-02
3.66E+00
Molybdenum trioxide
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Nickel compounds
lbs/yr
2.12E+01
7.98E-01
2.25E+02
Polycyclic aromatic compounds
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Selenium compounds
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Sulfuric acid
lbs/yr
2.24E+03
0.00E+00
0.00E+00
Vanadium compounds
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Zinc compounds
lbs/yr
1.69E+03
8.92E+02
7.85E+04
1.36E+01
7.19E+00
6.33E+02
Total
lbs/yr
4.45E+05
1.30E+03
1.36E+06
3.59E+03
1.05E+01
1.10E+04
4.65E+02
2.63E+03
2.80E+01
Lakeland Average per ton coal/hr
1.70E+01
2.65E+02
3.00E+00
9.90E+01
6.07E+04
4.07E+05
2.79E+04
2.78E+05
159
Table C-5. Continued
Crystal River
Air
Surface
Water
Crystal River Average per ton coal/hr
Land
Air
Surface
Water
Land
Arsenic compounds
lbs/yr
9.05E+02
1.27E+03
7.90E-01
0.00E+00
1.10E+00
Barium compounds
lbs/yr
2.61E+03
1.02E+04
2.27E+00
0.00E+00
8.88E+00
Beryllium compounds
lbs/yr
0.00E+00
0.00E+00
0.00E+00
Chromium compounds
lbs/yr
1.21E+03
2.06E+03
1.05E+00
0.00E+00
1.80E+00
Cobalt compounds
lbs/yr
3.05E+02
6.60E+02
2.66E-01
0.00E+00
5.76E-01
Copper compounds
lbs/yr
2.61E+03
2.33E+03
2.27E+00
1.48E+01
2.03E+00
Dioxin and Dioxin-like compounds
lbs/yr
6.31E-03
5.50E-06
0.00E+00
0.00E+00
Hydrochloric acid
lbs/yr
6.60E+06
5.76E+03
0.00E+00
0.00E+00
Hydrogen fluoride
lbs/yr
7.10E+05
5.20E+02
6.20E+02
0.00E+00
4.54E-01
Lead compounds
lbs/yr
8.25E+02
9.98E+02
7.20E-01
0.00E+00
8.71E-01
Manganese compounds
lbs/yr
1.51E+03
3.02E+03
1.31E+00
0.00E+00
2.64E+00
Mercury compounds
lbs/yr
2.05E+02
9.10E+00
1.79E-01
0.00E+00
7.94E-03
Molybdenum trioxide
lbs/yr
1.01E+03
5.20E+02
8.77E-01
0.00E+00
4.54E-01
Nickel compounds
lbs/yr
1.21E+03
1.96E+03
1.05E+00
1.66E+00
1.71E+00
Polycyclic aromatic compounds
lbs/yr
7.90E+00
0.00E+00
6.89E-03
0.00E+00
0.00E+00
Selenium compounds
lbs/yr
7.11E+03
3.62E+02
6.20E+00
0.00E+00
3.16E-01
Sulfuric acid
lbs/yr
7.40E+05
6.46E+02
0.00E+00
0.00E+00
Vanadium compounds
lbs/yr
1.51E+03
4.32E+03
1.31E+00
0.00E+00
3.77E+00
Zinc compounds
lbs/yr
9.05E+02
1.57E+03
7.90E-01
0.00E+00
1.37E+00
Total
lbs/yr
8.07E+06
2.98E+04
7.04E+03
1.65E+01
2.60E+01
1.70E+04
1.90E+03
1.89E+04
160
Table C-6: TRI emissions from disposal facilities at each utility
CristPensacola
Surface
Landfill Impoundement
Big BendTampa
Surface
Impoundement
LakelandMcIntosh
Landfill
Crystal River
Surface
Landfill Impoundement
Arsenic compounds
lbs/yr
5.64E+04
8.00E+02
2.99E+04
1.20E+03
6.50E+01
Barium compounds
lbs/yr
1.24E+05
7.90E+03
6.40E+05
1.00E+04
1.80E+02
Beryllium compounds
lbs/yr
Chromium compounds
lbs/yr
3.44E+04
3.50E+03
6.07E+04
2.00E+03
6.10E+01
Cobalt compounds
lbs/yr
1.90E+04
8.60E+02
6.60E+02
0.00E+00
Copper compounds
lbs/yr
2.88E+04
2.20E+03
1.30E+02
Hydrogen fluoride
lbs/yr
5.00E+02
2.00E+01
Lead compounds
lbs/yr
1.28E+05
9.90E+02
8.00E+00
Manganese compounds
lbs/yr
3.73E+04
Mercury compounds
lbs/yr
1.72E+02
Molybdenum trioxide
lbs/yr
Nickel compounds
lbs/yr
Selenium compounds
lbs/yr
Sulfuric acid
lbs/yr
Vanadium compounds
lbs/yr
6.27E+04
1.20E+04
Zinc compounds
lbs/yr
1.09E+05
2.18E+04
Total
lbs/yr
6.63E+05
8.77E+04
2.70E+02
5.87E+02
1.30E+03
4.07E+05
3.30E+03
1.70E+01
2.60E+04
1.15E+05
2.80E+03
2.20E+02
1.10E+01
4.54E+02
2.30E+00
6.80E+00
5.20E+02
0.00E+00
1.80E+03
1.60E+02
3.00E+02
6.20E+01
4.20E+03
1.20E+02
7.85E+04
1.20E+03
3.70E+02
1.36E+06
2.84E+04
1.40E+03
9.80E+02
6.34E+04
1.76E+02
9.01E+03
2.79E+04
.
7.80E+02
APPENDIX D
LIFE CYCLE ASSESMENT INVENTORY RESULTS
Table D-1: Inventory results for raw materials used
Substance
Coal Mining and
Preparation
(kg)
% of total
from
mining/prep
Coal
Combustion % of total from
(kg)
coal combustion
CCP
Beneficial Use
(kg)
% of total from
beneficial use
CCP
Disposal
(kg)
% of total
from disposal
Total
(kg)
water
1.26E+04
63.26%
3.58E+03
18.03%
3.28E+03
16.52%
4.36E+02
2.19%
1.99E+04
coal
1.81E+03
99.17%
1.37E+01
0.75%
1.17E+00
0.06%
3.62E-01
0.02%
1.83E+03
natural gas
9.73E+02
99.70%
2.10E+00
0.22%
-1.10E-01
-0.01%
9.80E-01
0.10%
9.76E+02
limestone
7.58E+00
2.22%
2.05E+02
59.83%
1.29E+02
37.83%
4.13E-01
0.12%
3.42E+02
gravel
8.41E+01
72.03%
2.85E+00
2.44%
-1.13E+01
-9.68%
4.11E+01
35.20%
1.17E+02
crude oil
2.94E+01
96.47%
7.69E-01
2.52%
-4.74E-01
-1.56%
7.79E-01
2.56%
3.05E+01
iron (in ore)
8.91E+00
84.69%
7.17E-01
6.81%
7.19E-01
6.83%
1.75E-01
1.66%
1.05E+01
wood
8.57E+00
98.89%
7.65E-02
0.88%
1.60E-02
0.18%
3.79E-03
0.04%
8.67E+00
methane
4.46E+00
99.93%
2.85E-02
0.64%
-2.72E-02
-0.61%
1.68E-03
0.04%
4.46E+00
rock salt
5.69E-01
13.46%
1.81E+00
42.80%
1.84E+00
43.51%
9.86E-03
0.23%
4.23E+00
lignite
1.10E-01
96.74%
2.02E-03
1.78%
1.37E-03
1.20%
3.21E-04
0.28%
1.14E-01
bentonite
8.86E-02
84.94%
7.14E-03
6.84%
6.68E-03
6.40%
1.89E-03
1.81%
1.04E-01
baryte
5.68E-02
91.20%
4.60E-03
7.39%
-2.45E-03
-3.93%
3.33E-03
5.35%
6.23E-02
4.77E-02
bauxite
1.59E-02
33.34%
1.54E-02
32.30%
1.55E-02
32.50%
8.85E-04
1.86%
lead (in ore)
4.16E-02
90.74%
2.54E-04
0.55%
2.87E-03
6.26%
1.12E-03
2.44%
4.58E-02
copper (in ore)
2.64E-02
59.76%
8.70E-03
19.69%
8.87E-03
20.08%
2.04E-04
0.46%
4.42E-02
chromium (in ore)
1.68E-02
78.54%
1.61E-03
7.53%
1.79E-03
8.37%
1.19E-03
5.56%
2.14E-02
manganese (in ore)
1.65E-02
84.06%
8.58E-04
4.37%
9.02E-04
4.60%
1.37E-03
6.98%
1.96E-02
nickel (in ore)
2.92E-03
63.25%
7.50E-04
16.25%
8.69E-04
18.82%
7.77E-05
1.68%
4.62E-03
zinc (in ore)
1.62E-03
94.43%
3.04E-05
1.77%
5.56E-05
3.24%
9.63E-06
0.56%
1.72E-03
silver (in ore)
8.68E-05
95.46%
2.77E-06
3.05%
-4.00E-06
-4.40%
5.36E-06
5.89%
9.09E-05
tin (in ore)
4.82E-05
95.45%
1.54E-06
3.05%
-2.22E-06
-4.40%
2.98E-06
5.90%
5.05E-05
uranium (in ore)
1.48E-04
70.40%
3.74E-05
17.76%
2.41E-05
11.45%
8.05E-07
0.38%
2.10E-04
cobalt (in ore)
7.12E-08
88.44%
1.93E-09
2.40%
2.78E-09
3.45%
4.60E-09
5.71%
8.05E-08
molybdene (in ore)
2.72E-08
83.44%
2.15E-09
6.60%
1.76E-09
5.40%
1.49E-09
4.57%
3.26E-08
platinum (in ore)
1.63E-08
87.62%
3.42E-10
1.84%
6.20E-10
3.33%
1.34E-09
7.20%
1.86E-08
rhodium (in ore)
1.47E-08
87.46%
3.15E-10
1.87%
5.42E-10
3.22%
1.25E-09
7.44%
1.68E-08
palladium (in ore)
1.36E-08
87.34%
2.95E-10
1.89%
4.97E-10
3.19%
1.18E-09
7.58%
1.56E-08
rhenium (in ore)
1.20E-08
87.92%
2.65E-10
1.94%
3.63E-10
2.66%
1.02E-09
7.47%
1.36E-08
silver
0.00E+00
0.00%
0.00E+00
0.00%
-1.55E-14
100.00%
0.00E+00
0.00%
-1.55E-14
zeolite
0.00E+00
0.00%
0.00E+00
0.00%
-2.92E-13
100.00%
0.00E+00
0.00%
-2.92E-13
iron (ore)
0.00E+00
0.00%
0.00E+00
0.00%
-3.15E-11
100.00%
0.00E+00
0.00%
-3.15E-11
sand
1.57E-01
-4.89%
5.96E-02
-1.86%
-3.43E+00
106.84%
3.14E-03
-0.10%
-3.21E+00
glass cullet
0.00E+00
0.00%
0.00E+00
0.00%
-3.79E+00
100.00%
0.00E+00
0.00%
-3.79E+00
clay
9.90E-01
-3.79%
7.40E-02
-0.28%
-2.73E+01
104.42%
9.19E-02
-0.35%
-2.61E+01
161
162
Table D-2: Inventory results for emissions to air
Coal Mining and % of total
Coal
% of total CCP Beneficial
Preparation
from
Combustion from coal
Use
% of total from
Substance
(kg)
mining/prep
(kg)
combustion
(kg)
beneficial use
2.89E+02
14.17%
9.12E+02
44.73%
8.35E+02
40.96%
CO2
SOx
1.20E+00
14.80%
3.55E+00
43.86%
3.34E+00
41.23%
NMVOC
6.83E+00
98.95%
4.28E-02
0.62%
1.49E-02
0.22%
CH4
6.28E+00
109.26%
1.00E-01
1.74%
-6.40E-01
-11.14%
NOx
2.08E+00
36.26%
1.92E+00
33.39%
1.72E+00
30.02%
Particulate
matter
7.92E-01
25.52%
7.07E-01
22.77%
5.52E-01
17.77%
HCl
9.19E-03
0.55%
8.24E-01
49.75%
8.23E-01
49.69%
CO
7.46E-01
72.52%
1.80E-01
17.50%
9.29E-02
9.03%
N2O
7.54E-03
28.29%
9.42E-03
35.35%
9.55E-03
35.83%
He
2.44E-02
99.76%
3.86E-05
0.16%
-5.53E-05
-0.23%
HF
1.02E-03
5.40%
8.97E-03
47.52%
8.88E-03
47.04%
ethene
1.19E-02
82.59%
4.45E-04
3.09%
9.73E-04
6.75%
7.94E-03
98.74%
5.32E-05
0.66%
3.75E-05
0.47%
formaldehyd
VOC
5.02E-03
100.00%
0.00E+00
0.00%
-1.03E-07
0.00%
Ba
7.13E-06
0.21%
1.72E-03
49.90%
1.72E-03
49.90%
ammonia
3.05E-03
96.76%
1.56E-04
4.95%
-5.67E-05
-1.80%
pentane
2.74E-03
89.53%
1.82E-04
5.95%
-2.66E-05
-0.87%
Si
9.02E-04
30.32%
1.04E-03
34.96%
1.03E-03
34.63%
Zn
1.57E-03
58.32%
5.13E-04
19.06%
5.83E-04
21.66%
propane
2.27E-03
85.00%
2.70E-04
10.11%
4.94E-07
0.02%
butane
2.21E-03
89.71%
1.55E-04
6.29%
-3.46E-05
-1.40%
aldehydes
2.17E-03
90.93%
1.48E-04
6.20%
6.66E-05
2.79%
K
1.60E-03
78.39%
2.06E-04
10.09%
2.05E-04
10.04%
Al
6.08E-04
30.51%
6.96E-04
34.92%
6.87E-04
34.47%
ethane
9.71E-04
57.66%
5.64E-04
33.49%
1.15E-04
6.83%
Cu
1.40E-03
94.27%
4.40E-05
2.96%
3.85E-05
2.59%
2.22E-03
150.24%
9.35E-05
6.33%
-8.38E-04
-56.71%
organic subst
Fe
7.83E-04
54.61%
3.22E-04
22.46%
3.17E-04
22.11%
Ni
2.04E-04
14.42%
6.11E-04
43.20%
5.96E-04
42.14%
xylene
1.29E-03
93.65%
3.68E-05
2.67%
3.09E-05
2.24%
N2
4.76E-04
40.80%
6.25E-04
53.57%
6.34E-05
5.43%
hexane
1.06E-03
95.00%
3.65E-05
3.27%
-4.56E-05
-4.09%
Mn
4.29E-04
41.33%
3.01E-04
29.00%
3.00E-04
28.90%
benzene
7.61E-04
75.46%
9.44E-05
9.36%
9.80E-05
9.72%
alkanes
6.88E-04
85.14%
6.30E-05
7.80%
2.13E-05
2.64%
Pb
2.21E-04
28.30%
2.78E-04
35.60%
2.77E-04
35.47%
Mg
2.32E-04
32.22%
2.45E-04
34.02%
2.42E-04
33.61%
Ca
4.15E-04
64.63%
1.11E-04
17.29%
1.09E-04
16.98%
H2S
4.89E-04
80.59%
7.22E-05
11.90%
3.64E-05
6.00%
heptane
5.05E-04
95.00%
1.74E-05
3.27%
-2.17E-05
-4.08%
butene
4.06E-04
85.93%
8.68E-06
1.84%
2.14E-05
4.53%
As
2.36E-05
5.12%
2.19E-04
47.50%
2.18E-04
47.29%
V
1.73E-04
38.37%
1.44E-04
31.93%
1.26E-04
27.94%
toluene
3.47E-04
85.06%
3.31E-05
8.11%
8.63E-06
2.12%
Cr
2.32E-05
5.79%
1.92E-04
47.95%
1.85E-04
46.20%
3.91E-04
99.87%
3.44E-07
0.09%
-4.77E-07
-0.12%
HALON-130
propene
1.87E-04
68.90%
3.96E-05
14.59%
3.37E-05
12.42%
Se
3.72E-05
14.60%
1.16E-04
45.53%
1.01E-04
39.64%
B
5.91E-05
30.03%
6.92E-05
35.16%
6.84E-05
34.76%
Na
8.85E-05
49.63%
4.69E-05
26.30%
4.04E-05
22.65%
4.98E-06
3.27%
7.40E-05
48.52%
7.35E-05
48.20%
dichlorometh
HCFC-21
9.97E-05
69.46%
1.49E-05
10.38%
1.96E-05
13.66%
alkenes
5.31E-05
42.97%
3.52E-05
28.49%
3.50E-05
28.33%
Hg
4.59E-06
4.38%
5.13E-05
48.94%
4.89E-05
46.65%
ethyne
3.09E-05
30.80%
3.49E-05
34.79%
3.44E-05
34.29%
cobalt
1.04E-05
13.13%
3.45E-05
43.55%
3.42E-05
43.17%
Ti
2.08E-05
30.08%
2.43E-05
35.14%
2.40E-05
34.70%
phenol
4.09E-06
6.93%
3.18E-05
53.89%
2.31E-05
39.15%
CCP
% of total
Disposal
from
(kg)
disposal
2.78E+00
0.14%
9.44E-03
0.12%
1.50E-02
0.22%
7.60E-03
0.13%
1.86E-02
0.32%
Total
(kg)
2.04E+03
8.10E+00
6.90E+00
5.75E+00
5.74E+00
1.05E+00
4.33E-05
9.73E-03
1.40E-04
7.55E-05
5.66E-06
1.09E-03
1.04E-05
0.00E+00
1.99E-08
2.83E-06
1.65E-04
2.61E-06
2.62E-05
1.30E-04
1.33E-04
1.88E-06
3.02E-05
2.02E-06
3.41E-05
2.64E-06
2.10E-06
1.17E-05
3.49E-06
1.98E-05
2.39E-06
6.49E-05
7.97E-06
5.51E-05
3.58E-05
5.00E-06
1.06E-06
7.09E-06
9.20E-06
3.09E-05
3.64E-05
4.32E-07
7.93E-06
1.92E-05
2.07E-07
6.61E-07
1.11E-05
5.68E-07
1.03E-07
2.53E-06
2.27E-08
9.33E-06
2.62E-07
4.21E-08
1.14E-07
1.27E-07
5.91E-08
1.52E-08
3.10E+00
1.66E+00
1.03E+00
2.67E-02
2.45E-02
1.89E-02
1.44E-02
8.04E-03
5.02E-03
3.45E-03
3.15E-03
3.06E-03
2.97E-03
2.69E-03
2.67E-03
2.46E-03
2.39E-03
2.04E-03
1.99E-03
1.68E-03
1.49E-03
1.48E-03
1.43E-03
1.41E-03
1.38E-03
1.17E-03
1.12E-03
1.04E-03
1.01E-03
8.08E-04
7.81E-04
7.20E-04
6.42E-04
6.07E-04
5.32E-04
4.72E-04
4.61E-04
4.51E-04
4.08E-04
4.00E-04
3.92E-04
2.71E-04
2.55E-04
1.97E-04
1.78E-04
1.53E-04
1.44E-04
1.24E-04
1.05E-04
1.00E-04
7.92E-05
6.92E-05
5.90E-05
33.94%
0.00%
0.95%
0.53%
0.31%
0.03%
7.57%
0.13%
0.00%
0.00%
0.09%
5.39%
0.09%
0.97%
4.87%
5.40%
0.08%
1.48%
0.10%
2.02%
0.18%
0.14%
0.82%
0.25%
1.44%
0.20%
5.82%
0.77%
5.46%
4.43%
0.64%
0.15%
1.10%
1.52%
5.81%
7.70%
0.09%
1.76%
4.71%
0.05%
0.17%
4.09%
0.22%
0.05%
1.42%
0.01%
6.50%
0.21%
0.04%
0.11%
0.16%
0.09%
0.03%
163
Table D-2. Continued
Coal Mining
% of total
Coal
% of total
CCP
% of total
and Preparation
from
Combustion from coal Beneficial Use
from
Substance
(kg)
mining/prep
(kg)
combustion
(kg)
beneficial use
ethylbenzene
5.11E-05
95.02%
1.75E-06
3.25%
-2.16E-06
-4.02%
acetic acid
1.81E-05
41.43%
1.30E-05
29.76%
1.24E-05
28.38%
kerosene
2.98E-05
69.17%
8.01E-06
18.59%
5.14E-06
11.93%
Br
1.27E-05
31.49%
1.39E-05
34.46%
1.37E-05
33.97%
Sr
1.15E-05
29.39%
1.39E-05
35.53%
1.37E-05
35.01%
tetrachloromethane
1.92E-06
4.98%
1.84E-05
47.76%
1.82E-05
47.24%
acrolein
1.21E-06
3.53%
1.66E-05
48.37%
1.65E-05
48.08%
tetrachloroethene
1.11E-06
3.42%
1.57E-05
48.43%
1.56E-05
48.13%
trichloroethene
1.10E-06
3.39%
1.57E-05
48.45%
1.56E-05
48.14%
Sb
2.58E-06
8.30%
1.43E-05
46.00%
1.42E-05
45.68%
metals
1.74E-05
76.15%
3.35E-06
14.66%
2.04E-06
8.93%
P-tot
7.09E-06
36.12%
6.45E-06
32.86%
6.01E-06
30.61%
Cd
1.34E-05
73.01%
3.28E-06
17.87%
1.50E-06
8.17%
methanol
1.04E-05
75.37%
1.83E-06
13.26%
1.43E-06
10.36%
Be
8.23E-07
7.62%
5.01E-06
46.41%
4.96E-06
45.94%
I
3.66E-06
34.65%
3.47E-06
32.85%
3.42E-06
32.38%
CxHy aromatic
6.35E-06
76.83%
9.82E-07
11.88%
7.95E-07
9.62%
ethanol
6.25E-06
75.72%
1.08E-06
13.08%
8.43E-07
10.21%
n-nitrodimethylamine
2.47E-07
3.41%
3.51E-06
48.43%
3.49E-06
48.15%
PAH's
3.34E-06
52.80%
1.45E-06
22.92%
1.47E-06
23.24%
acetaldehyde
3.68E-06
76.06%
6.17E-07
12.75%
4.97E-07
10.27%
CFC-14
1.55E-06
33.36%
1.50E-06
32.28%
1.51E-06
32.50%
acetone
3.24E-06
76.14%
5.42E-07
12.74%
4.25E-07
9.99%
propionic acid
7.43E-07
20.49%
1.45E-06
39.98%
1.43E-06
39.43%
Cl2
3.45E-06
96.20%
1.00E-07
2.79%
3.17E-08
0.88%
cyanides
2.57E-06
84.69%
2.07E-07
6.82%
2.07E-07
6.82%
MTBE
1.92E-06
92.01%
1.95E-08
0.93%
1.15E-07
5.51%
Mo
1.29E-06
65.09%
3.77E-07
19.02%
2.65E-07
13.37%
benzo(a)pyrene
9.40E-07
85.47%
7.01E-08
6.37%
7.15E-08
6.50%
La
1.90E-07
31.32%
2.09E-07
34.45%
2.07E-07
34.12%
CFC-116
1.73E-07
33.42%
1.67E-07
32.26%
1.68E-07
32.46%
Th
1.20E-07
30.28%
1.39E-07
35.07%
1.37E-07
34.56%
U
1.16E-07
29.57%
1.39E-07
35.43%
1.37E-07
34.92%
dichloroethane
1.67E-07
76.44%
2.64E-08
12.08%
2.00E-08
9.15%
Sc
6.48E-08
31.77%
6.99E-08
34.27%
6.90E-08
33.83%
Tl
5.78E-08
29.51%
6.94E-08
35.44%
6.85E-08
34.98%
Sn
9.31E-08
51.48%
4.24E-08
23.44%
4.44E-08
24.55%
Zr
1.12E-07
84.96%
9.09E-09
6.90%
8.54E-09
6.48%
CFC-114
1.09E-07
86.54%
8.76E-09
6.95%
6.56E-09
5.21%
Pt
1.08E-07
91.75%
1.11E-09
0.94%
6.72E-09
5.71%
naphthalene
7.70E-08
73.41%
1.70E-08
16.21%
1.06E-08
10.11%
vinyl chloride
2.72E-08
76.46%
4.29E-09
12.06%
3.26E-09
9.16%
benzaldehyde
1.36E-08
89.70%
1.95E-10
1.29%
4.45E-10
2.93%
trichloromethane
4.42E-09
76.47%
6.97E-10
12.06%
5.29E-10
9.15%
CFC-11
3.85E-09
87.45%
2.86E-10
6.50%
2.13E-10
4.84%
dioxin (TEQ)
3.50E-11
1.39%
1.25E-09
49.69%
1.23E-09
48.89%
HCFC-22
9.86E-10
86.42%
8.00E-11
7.01%
6.00E-11
5.26%
CFC-12
8.27E-10
87.44%
6.14E-11
6.49%
4.59E-11
4.85%
CFC-13
5.19E-10
87.43%
3.86E-11
6.50%
2.88E-11
4.85%
pentachlorobenzene
1.63E-10
91.91%
2.42E-12
1.36%
9.43E-12
5.32%
hexachlorobenzene
6.09E-11
91.90%
9.06E-13
1.37%
3.53E-12
5.33%
pentachlorophenol
2.63E-11
91.91%
3.91E-13
1.37%
1.52E-12
5.31%
1,2-dichloroethane
0.00E+00
0.00%
0.00E+00
0.00%
-7.21E-16
100.00%
P
0.00E+00
0.00%
0.00E+00
0.00%
-3.88E-14
100.00%
silicates
0.00E+00
0.00%
0.00E+00
0.00%
-5.35E-12
100.00%
soot
0.00E+00
0.00%
0.00E+00
0.00%
-2.90E-10
100.00%
CxHy
0.00E+00
0.00%
0.00E+00
0.00%
-2.11E-08
100.00%
CCP
% of total
Disposal
from
(kg)
disposal
3.09E-06
5.75%
1.89E-07
0.43%
1.34E-07
0.31%
3.54E-08
0.09%
2.69E-08
0.07%
9.72E-09
0.03%
7.93E-09
0.02%
4.99E-09
0.02%
4.95E-09
0.02%
5.45E-09
0.02%
6.04E-08
0.26%
8.13E-08
0.41%
1.73E-07
0.94%
1.38E-07
1.00%
2.66E-09
0.02%
1.27E-08
0.12%
1.38E-07
1.67%
8.14E-08
0.99%
1.11E-09
0.02%
6.63E-08
1.05%
4.44E-08
0.92%
8.66E-08
1.86%
4.83E-08
1.14%
3.46E-09
0.10%
4.42E-09
0.12%
5.06E-08
1.67%
3.22E-08
1.54%
4.99E-08
2.52%
1.82E-08
1.65%
7.26E-10
0.12%
9.62E-09
1.86%
3.60E-10
0.09%
2.73E-10
0.07%
5.07E-09
2.32%
2.70E-10
0.13%
1.35E-10
0.07%
9.54E-10
0.53%
2.20E-09
1.67%
1.64E-09
1.30%
1.88E-09
1.60%
2.97E-10
0.28%
8.25E-10
2.32%
9.22E-10
6.08%
1.34E-10
2.32%
5.34E-11
1.21%
6.00E-13
0.02%
1.50E-11
1.31%
1.15E-11
1.22%
7.21E-12
1.21%
2.49E-12
1.40%
9.33E-13
1.41%
4.03E-13
1.41%
0.00E+00
0.00%
0.00E+00
0.00%
0.00E+00
0.00%
0.00E+00
0.00%
0.00E+00
0.00%
Total
(kg)
5.38E-05
4.37E-05
4.31E-05
4.03E-05
3.91E-05
3.85E-05
3.43E-05
3.24E-05
3.24E-05
3.11E-05
2.29E-05
1.96E-05
1.84E-05
1.38E-05
1.08E-05
1.06E-05
8.27E-06
8.25E-06
7.25E-06
6.33E-06
4.84E-06
4.65E-06
4.26E-06
3.63E-06
3.59E-06
3.03E-06
2.09E-06
1.98E-06
1.10E-06
6.07E-07
5.18E-07
3.96E-07
3.92E-07
2.18E-07
2.04E-07
1.96E-07
1.81E-07
1.32E-07
1.26E-07
1.18E-07
1.05E-07
3.56E-08
1.52E-08
5.78E-09
4.40E-09
2.52E-09
1.14E-09
9.46E-10
5.94E-10
1.77E-10
6.63E-11
2.86E-11
-7.21E-16
-3.88E-14
-5.35E-12
-2.90E-10
-2.11E-08
164
Table D-3: Inventory results for emissions to water
Substance
ClSulphate
Dissolved solids
Na
Al
Ca
Mg
K
Fe
Ba
TOC
Suspended solids
Phosphate
B
Ti
Sr
Mn
fats and oils
baryte
Pb
COD
Mo
N-tot
fluoride ions
CxHy aromatic
Zn
nitrate
NH3 (as N)
other organics
Cr
VOC as C
Si
BOD
Ni
Se
V
Cu
benzene
alkanes
Ag
phenols
toluene
I
xylene
As
Co
N organically
bound
Cd
W
metallic ions
ethyl benzene
PAH's
alkenes
% of total
CCP
Coal Mining
from
CCP
% of total
and
% of total
Coal
% of total Beneficial
beneficial Disposal
from
Use
Preparation
from
Combustion from coal
use
(kg)
disposal
(kg)
(kg)
mining/prep
(kg)
combustion
1.43E+01
0.54%
7.98E-02
96.07% -3.42E-02
-0.23% 5.40E-01
3.63%
1.28E+01
1.12%
1.48E-01
97.08%
8.01E-02
0.61% 1.57E-01
1.19%
1.73E+00
0.91%
8.80E-02
17.87%
3.22E-02
0.33% 7.85E+00
80.89%
5.94E+00
0.37%
2.23E-02
99.16% -1.24E-02
-0.21% 4.05E-02
0.68%
3.01E+00
0.24%
7.20E-03
99.92% -7.50E-03
-0.25% 2.68E-03
0.09%
2.26E+00
1.85%
4.65E-02
89.69%
3.32E-02
1.32% 1.80E-01
7.14%
2.41E+00
0.24%
5.82E-03
99.92% -6.11E-03
-0.25% 2.15E-03
0.09%
9.47E-01
0.25%
2.38E-03
99.22% -2.55E-03
-0.27% 7.64E-03
0.80%
9.11E-01
0.40%
3.69E-03
98.23% -1.20E-03
-0.13% 1.39E-02
1.50%
2.68E-01
0.24%
6.84E-04
95.26% -7.58E-04
-0.27% 1.34E-02
4.76%
2.35E-01
1.25%
3.12E-03
94.38%
7.89E-03
3.17% 2.98E-03
1.20%
1.69E-01
24.89%
7.94E-02
53.12%
6.52E-02
20.45% 4.90E-03
1.54%
1.81E-01
5.66%
1.15E-02
89.11%
1.06E-02
5.22% 2.51E-05
0.01%
4.03E-03
48.12%
8.89E-02
2.18%
8.85E-02
47.90% 3.33E-03
1.80%
1.81E-01
0.24%
4.33E-04
99.74% -4.47E-04
-0.25% 4.88E-04
0.27%
7.43E-02
0.38%
2.82E-04
99.23% -4.05E-04
-0.54% 6.99E-04
0.93%
6.47E-02
1.31%
8.70E-04
97.36%
3.05E-04
0.46% 5.76E-04
0.87%
9.35E-02
2.68%
2.61E-03
96.05% -8.09E-04
-0.83% 2.05E-03
2.10%
2.47E-02
5.43%
1.44E-03
93.10% -1.09E-03
-4.11% 1.48E-03
5.58%
1.52E-02
1.85%
3.17E-04
88.83%
2.44E-04
1.43% 1.35E-03
7.89%
1.14E-02
10.10%
1.39E-03
82.87%
6.28E-04
4.57% 3.38E-04
2.46%
7.53E-03
0.25%
2.18E-05
87.39% -1.50E-05
-0.17% 1.08E-03
12.53%
3.05E-03
1.07%
8.26E-05
39.52% -1.42E-05
-0.18% 4.60E-03
59.60%
5.21E-03
2.66%
1.65E-04
84.01%
1.32E-04
2.13% 6.95E-04
11.21%
5.78E-03
0.50%
2.91E-05
99.27% -3.75E-05
-0.64% 5.10E-05
0.88%
3.30E-03
11.24%
6.37E-04
58.21%
6.22E-04
10.97% 1.11E-03
19.58%
4.85E-03
1.62%
8.29E-05
94.53%
9.90E-05
1.93% 9.89E-05
1.93%
4.74E-03
1.94%
9.66E-05
95.40% -1.02E-05
-0.21% 1.42E-04
2.86%
1.82E-03
31.62%
1.40E-03
41.11%
1.20E-03
27.11% 7.05E-06
0.16%
3.08E-03
0.37%
1.62E-05
69.57% -1.76E-06
-0.04% 1.33E-03
30.11%
3.82E-03
0.39%
1.51E-05
99.40% -2.21E-05
-0.58% 2.99E-05
0.78%
3.65E-06
0.15%
4.54E-06
0.12%
4.16E-06
0.13% 3.09E-03
99.60%
1.67E-03
8.43%
1.67E-04
84.33%
1.13E-04
5.71% 3.02E-05
1.53%
1.66E-03
2.81%
5.10E-05
91.31%
4.28E-05
2.35% 6.41E-05
3.53%
1.51E-03
0.21%
3.65E-06
84.98% -3.78E-06
-0.21% 2.67E-04
15.03%
1.51E-03
0.24%
4.16E-06
88.47% -3.28E-06
-0.19% 1.96E-04
11.48%
1.53E-03
0.47%
7.25E-06
98.85% -9.13E-08
-0.01% 1.07E-05
0.69%
1.42E-03
0.42%
6.07E-06
99.34% -8.11E-06
-0.57% 1.15E-05
0.80%
1.42E-03
0.42%
5.96E-06
99.38% -8.20E-06
-0.57% 1.11E-05
0.78%
7.12E-06
0.01%
7.27E-08
0.54%
9.20E-09
0.00% 1.30E-03
99.45%
1.25E-03
0.75%
9.45E-06
98.77% -5.43E-06
-0.43% 1.15E-05
0.91%
1.18E-03
0.42%
5.03E-06
99.35% -6.74E-06
-0.57% 9.42E-06
0.79%
1.09E-03
0.39%
4.31E-06
99.40% -6.31E-06
-0.58% 8.61E-06
0.79%
1.03E-03
0.42%
4.34E-06
99.36% -5.84E-06
-0.56% 8.17E-06
0.79%
6.04E-04
1.07%
9.68E-06
66.64%
6.65E-06
0.73% 2.86E-04
31.56%
6.02E-04
0.24%
1.46E-06
97.64% -1.48E-06
-0.24% 1.46E-05
2.37%
4.56E-04
2.09E-04
4.84E-07
3.90E-04
2.62E-04
1.42E-04
1.31E-04
2.23%
1.03%
0.14%
2.02%
0.39%
0.45%
0.42%
1.12E-05
4.99E-06
6.02E-07
8.07E-06
1.03E-06
6.49E-07
5.49E-07
90.85%
43.15%
0.11%
97.51%
99.40%
99.28%
99.38%
4.91E-06
3.32E-06
5.94E-07
1.44E-06
-1.51E-06
-7.34E-07
-7.57E-07
0.98%
0.69%
0.13%
0.36%
-0.57%
-0.51%
-0.57%
2.98E-05
2.67E-04
4.42E-04
4.56E-07
2.05E-06
1.12E-06
1.02E-06
5.94%
55.13%
99.62%
0.11%
0.78%
0.78%
0.77%
Total
(kg)
1.49E+01
1.32E+01
9.70E+00
5.99E+00
3.01E+00
2.52E+00
2.41E+00
9.54E-01
9.27E-01
2.81E-01
2.49E-01
3.19E-01
2.03E-01
1.85E-01
1.81E-01
7.49E-02
6.65E-02
9.74E-02
2.65E-02
1.71E-02
1.38E-02
8.62E-03
7.72E-03
6.20E-03
5.82E-03
5.67E-03
5.13E-03
4.97E-03
4.43E-03
4.42E-03
3.84E-03
3.10E-03
1.98E-03
1.82E-03
1.78E-03
1.71E-03
1.55E-03
1.43E-03
1.43E-03
1.31E-03
1.27E-03
1.19E-03
1.10E-03
1.04E-03
9.06E-04
6.17E-04
5.02E-04
4.84E-04
4.44E-04
4.00E-04
2.64E-04
1.43E-04
1.32E-04
165
Table D-3. Continued
Coal Mining
CCP
% of total
and
% of total
Coal
% of total Beneficial
from
CCP
% of total
Preparation
from
Combustion from coal
Use
beneficial Disposal
from
Substance
(kg)
mining/prep
(kg)
combustion
(kg)
use
(kg)
disposal
Ru
1.09E-04
0.37%
4.48E-07
89.10% -6.14E-07
-0.50% 1.35E-05
11.04%
NH3
8.04E-05
13.66%
1.41E-05
77.91% 8.44E-06
8.18% 2.61E-07
0.25%
SO3
6.63E-05
1.01%
7.26E-07
92.40% 3.74E-06
5.21% 9.91E-07
1.38%
DOC
2.54E-05
55.82%
3.24E-05
43.76% 1.22E-07
0.21% 1.24E-07
0.21%
triethylene glycol
2.54E-05
55.82%
3.24E-05
43.76% 1.22E-07
0.21% 1.24E-07
0.21%
cyanide
4.27E-05
6.37%
3.16E-06
86.04% 2.70E-06
5.44% 1.07E-06
2.16%
sulphide
4.50E-05
2.85%
1.34E-06
95.81% -2.14E-06
-4.56% 2.77E-06
5.90%
acids
(unspecified)
2.80E-05
6.89%
2.27E-06
84.95% 2.14E-06
6.49% 5.50E-07
1.67%
Hg
4.68E-07
2.08%
5.83E-07
1.67% 5.75E-07
2.05% 2.64E-05
94.20%
Sb
5.42E-07
0.55%
1.07E-07
2.77% 1.07E-07
0.55% 1.88E-05
96.13%
H2S
1.11E-05
6.85%
8.97E-07
84.82% 8.71E-07
6.66% 2.18E-07
1.67%
Cs
1.09E-05
0.36%
4.51E-08
87.59% -6.11E-08
-0.49% 1.56E-06
12.54%
CxHy
6.53E-06
2.93%
2.05E-07
93.30% -1.45E-07
-2.07% 4.09E-07
5.84%
chromate
5.79E-06
3.64%
2.23E-07
94.49% 1.06E-07
1.73% 8.66E-09
0.14%
Be
5.49E-09
0.14%
6.45E-09
0.12% 6.36E-09
0.14% 4.46E-06
99.59%
glutaraldehyde
3.06E-06
5.42%
1.78E-07
93.12% -1.35E-07
-4.11% 1.83E-07
5.57%
tributyltin
1.99E-06
11.13%
2.37E-07
93.46% -1.85E-07
-8.69% 8.72E-08
4.10%
OCl1.22E-06
17.82%
3.37E-07
64.52% 3.30E-07
17.45% 3.94E-09
0.21%
phenol
1.27E-06
2.02%
2.63E-08
97.50% 4.77E-09
0.37% 1.49E-09
0.11%
HOCL
1.22E-06
1.92%
2.43E-08
96.42% 1.71E-08
1.35% 3.93E-09
0.31%
acenaphthylene
6.01E-07
49.03%
6.00E-07
49.11% 1.68E-08
1.37% 5.99E-09
0.49%
chlorinated
solvents
9.90E-07
6.79%
7.93E-08
84.71% 7.97E-08
6.82% 1.97E-08
1.69%
nitrite
7.53E-07
6.65%
5.76E-08
86.96% 3.89E-08
4.49% 1.64E-08
1.89%
dichloro-methane
2.38E-07
55.67%
3.02E-07
43.87% 1.27E-09
0.23% 1.22E-09
0.22%
MTBE
1.59E-07
0.94%
1.62E-09
92.07% 9.44E-09
5.47% 2.64E-09
1.53%
P-compounds
1.19E-07
16.02%
2.41E-08
79.12% 3.63E-09
2.41% 3.68E-09
2.45%
dichloroethane
8.60E-08
12.09%
1.36E-08
76.44% 1.03E-08
9.15% 2.61E-09
2.32%
Total
(kg)
1.22E-04
1.03E-04
7.18E-05
5.80E-05
5.80E-05
4.96E-05
4.70E-05
3.30E-05
2.80E-05
1.96E-05
1.31E-05
1.24E-05
7.00E-06
6.13E-06
4.48E-06
3.29E-06
2.13E-06
1.89E-06
1.30E-06
1.27E-06
1.22E-06
1.17E-06
8.66E-07
5.42E-07
1.73E-07
1.50E-07
1.13E-07
tri-chloromethane
1,1,1trichloroethane
formaldehyde
Acid as H+
trichloroethene
Sn
dimethyl pphthalate
tetrachloromethane
di(2-ethylhexyl)
phthalate
5.38E-08
11.83%
8.29E-09
76.76%
6.37E-09
9.09%
1.63E-09
2.33%
7.01E-08
4.69E-08
1.36E-07
1.84E-08
1.43E-08
1.78E-09
0.56%
45.16%
2.02%
12.08%
2.21%
2.88E-10
1.14E-08
3.81E-10
2.26E-09
4.14E-11
90.68%
538.81%
97.50%
76.41%
94.91%
3.23E-09
-1.23E-07
6.89E-11
1.72E-09
4.36E-11
6.25%
-487.30%
0.37%
9.19%
2.32%
1.30E-09
8.41E-10
2.15E-11
4.34E-10
1.05E-11
2.51%
3.33%
0.11%
2.32%
0.56%
5.17E-08
2.52E-08
1.89E-08
1.87E-08
1.88E-09
3.83E-10
49.07%
3.83E-10
49.07%
1.07E-11
1.37%
3.82E-12
0.49%
7.81E-10
3.46E-10
12.06%
5.46E-11
76.45%
4.15E-11
9.17%
1.05E-11
2.32%
4.53E-10
3.63E-10
0.84%
3.39E-12
90.32%
2.54E-11
6.32%
1.01E-11
2.51%
4.02E-10
tetra-chloroethene
2.27E-10
12.06%
3.58E-11
76.46%
2.72E-11
9.16%
6.88E-12
2.32%
2.97E-10
dibutyl p-phthalate
chlorobenzenes
vinyl chloride
6.09E-11
1.02E-10
6.44E-11
49.03%
1.66%
12.11%
6.08E-11
2.00E-12
1.02E-11
49.11%
84.81%
76.43%
1.70E-12
6.73E-12
7.71E-12
1.37%
5.60%
9.15%
6.06E-13
9.54E-12
1.95E-12
0.49%
7.93%
2.31%
1.24E-10
1.20E-10
8.43E-11
hexa-chloroethane
P-tot
CxHy chloro
S
salt
H2
crude oil
1.91E-12
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
12.05%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
3.01E-13
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
76.46%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
2.29E-13
-2.89E-17
-3.13E-16
-8.04E-15
-7.43E-12
-8.66E-11
-9.32E-11
9.17%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
5.79E-14
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
2.32%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
2.50E-12
-2.89E-17
-3.13E-16
-8.04E-15
-7.43E-12
-8.66E-11
-9.32E-11
166
Table D-4: Inventory results for emissions to soil
Coal Mining
CCP
% of total
and
% of total
Coal
% of total Beneficial
from
CCP
% of total
Preparation from coal Combustion
from
Use
beneficial Disposal
from
Substance
(kg)
combustion
(kg)
mining/prep
(kg)
use
(kg)
disposal
Ba
1.57E-02
0.36%
1.95E-02
0.45% 1.92E-02
0.44% 4.32E+00
98.76%
Cu
9.58E-03
0.36%
1.19E-02
0.45% 1.18E-02
0.44% 2.64E+00
98.76%
Mn
3.08E-03
0.36%
3.83E-03
0.44% 3.78E-03
0.44% 8.50E-01
98.76%
Zn
2.69E-03
0.36%
3.35E-03
0.45% 3.31E-03
0.44% 7.43E-01
98.76%
Cr
1.66E-03
0.36%
2.07E-03
0.45% 2.04E-03
0.44% 4.58E-01
98.76%
Ni
1.14E-03
0.36%
1.42E-03
0.45% 1.40E-03
0.44% 3.14E-01
98.75%
As
1.08E-03
0.36%
1.35E-03
0.45% 1.33E-03
0.44% 2.99E-01
98.76%
Pb
8.97E-04
0.36%
1.12E-03
0.45% 1.10E-03
0.44% 2.47E-01
98.75%
V
5.14E-04
0.36%
6.40E-04
0.45% 6.32E-04
0.44% 1.42E-01
98.76%
Co
1.37E-04
0.36%
1.70E-04
0.45% 1.68E-04
0.44% 3.77E-02
98.76%
Hg
1.17E-05
0.36%
1.46E-05
0.45% 1.44E-05
0.44% 3.24E-03
98.76%
Mo
7.54E-06
0.36%
9.39E-06
0.45% 9.27E-06
0.44% 2.08E-03
98.76%
oil
1.54E-03
96.30%
4.03E-05
2.51% -5.46E-05
-3.41% 7.37E-05
4.59%
Be
1.72E-06
0.36%
2.15E-06
0.45% 2.12E-06
0.44% 4.76E-04
98.76%
C
2.70E-04
65.87%
1.36E-04
33.18% -6.73E-06
-1.64% 1.06E-05
2.59%
HF
1.30E-06
0.36%
1.61E-06
0.44% 1.59E-06
0.44% 3.58E-04
98.76%
Ca
1.36E-04
43.69%
1.74E-04
55.89% 6.53E-07
0.21% 6.63E-07
0.21%
Se
9.03E-07
0.36%
1.12E-06
0.44% 1.11E-06
0.44% 2.49E-04
98.76%
Fe
6.82E-05
43.79%
8.69E-05
55.79% 3.26E-07
0.21% 3.32E-07
0.21%
Al
3.41E-05
43.76%
4.35E-05
55.82% 1.63E-07
0.21% 1.66E-07
0.21%
S
2.14E-05
44.85%
2.61E-05
54.70% 5.38E-08
0.11% 1.57E-07
0.33%
P
5.16E-06
66.66%
2.37E-06
30.62% 6.32E-08
0.82% 1.48E-07
1.91%
N
1.77E-06
93.43%
7.16E-08
3.78% -4.31E-08
-2.28% 9.59E-08
5.06%
Cd
1.02E-07
93.50%
1.91E-09
1.75% 2.52E-09
2.31% 2.66E-09
2.44%
Total
(kg)
4.37E+00
2.67E+00
8.61E-01
7.52E-01
4.64E-01
3.18E-01
3.03E-01
2.50E-01
1.44E-01
3.82E-02
3.28E-03
2.11E-03
1.60E-03
4.82E-04
4.10E-04
3.63E-04
3.11E-04
2.52E-04
1.56E-04
7.79E-05
4.77E-05
7.74E-06
1.89E-06
1.09E-07
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BIOGRAPHICAL SKETCH
Callie Jane Whitfield received her Bachelor of Science in chemical engineering
from the Georgia Institute of Technology in 2001 and her Master of Engineering in
environmental engineering sciences from the University of Florida in 2003. Ms.
Whitfield is currently working towards her Ph.D. in environmental engineering sciences
with research interests in pollution prevention, life cycle assessment, and industrial
ecology. She has also performed research with Greening UF, a grassroots environmental
initiative that seeks to increase environmental literacy, examine current practices to
reduce environmental impact, and to create a culture of environmental stewardship on the
University of Florida campus. Ms. Whitfield’s research interests at Greening UF have
included a campus-wide greenhouse gas inventory and reduction plan, the state of
sustainability-related education on campus, green building, and sustainability indicators.
176