Waste to Energy Technology for Improving the Environment
Waste to Energy Technology for Improving Air Quality in Las Vegas
Brief: This white paper is provided as an example of the air quality impact of an air fed waste to
energy gasification facility. The assessment described in this paper showed that construction
and operation of the an EnviroPower Renewable (EPR) 48 MW Gasification Facility in North Las
Vegas would have an overall positive environmental impact on air quality in the Las Vegas
valley, when compared to the present Air Quality status as well as alternatives for both solid
waste disposal and generation of renewable electrical energy.
Introduction and Overview
When considering the construction and operation of renewable energy power plants, assessing
the environmental impacts, and any potential for related impacts on health risk represented by
the new facilities, is paramount. In order to understand the potential for effects on health risk,
current ambient concentrations of various pollutants of concern in the local environment are
first determined. These existing ambient concentrations are then compared with those
associated with the new facility, and the possible effects of any contribution from the new
facility is identified and quantified to the extent possible.
Air quality in the Las Vegas Valley is monitored on a near continuous basis. As an overview of
the information provided in this document, Table 1 compares the air concentrations of criteria
pollutants under National Ambient Air Quality Standards (NAAQS) to concentrations of these
constituents as reported by the USEPA for the Las Vegas Valley in 2012, and specifically for
North Las Vegas in 2009. The data are then compared to the ground level concentrations for
the same NAAQS constituents that would result from operation of the EPR waste to energy
gasification facility. Comparisons are in terms of maximum ground level concentrations; the
parameter of significance in determination of potential health effects.
Table 1 Air Quality in the Las Vegas Valley and North Las Vegas as compared to NAAQ Standards
under the Clean Air Act, the US Average, and EPR Emissions concentrations at ground level
Criteria Pollutant
Particulate Matter PM 2.5
Particulate Matter PM10
(Course)
Ozone
(O3)
Carbon Monoxide (CO)
Nitrogen Dioxide (NOx)
Sulfur Dioxide
(SOx)
NAAQS
3
35 ug/m
150ug/ m3
35ug/ m3
0.075 ppm
9 ppm
53 ppb
75 ppb
EnviroPower Renewable, Inc.
LV 2012
3
NLV 2009
US Avg.
EPR
21 ug/m
139 ug/ m3
3
8.5 ug/m
24ug/ m3
3
9.5ug/m
20ug/ m3
0.03ug/m3
0.04 ug/ m3
0.085 ppm
3 ppm
14 ppb
9 ppb
.048 ppm
0.59ppm
7 ppb
1.2 ppb
.045 ppm
0.34 ppm
9 ppb
20 ppb
N/D
0.0009 ppm
0.043 ppb
0.45 ppb
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As described in detail in this document, results from this analysis (as shown in Table 1), based
largely on data from recent studies carried out on air quality in the Las Vegas valley,
demonstrate that the proposed EPR facility would have a clear positive impact on the local
environment in terms of air quality. This improvement would accrue from reduced diesel truck
traffic on I-15 to otherwise required haul waste to the Apex landfill, reduced overall emission of
greenhouse gas equivalents, and a average reduction in particulate matter in the ambient air as
a result of its extensive precipitation and removal from the stack gas by equipment at EPR.
National Ambient Air Quality Standards (NAAQS): NAAQS are EPA outdoor air quality
standards established under authority of the Clean Air Act and apply throughout the US.
Primary standards are designed to protect human health, with an adequate margin of safety,
even for sensitive populations. Secondary standards are designed to protect public welfare
from known of possible anticipated adverse effects. A jurisdiction that meets these standards is
known as an attainment area, while one that does not is known as a non-attainment area. Prior
to 2012, the Las Vegas Valley (Hydrographic Area 212), had been designated as a nonattainment area for particulate matter (24 hr. PM10) under the Clean Air Act (Clark County DAQ,
2012). NAAQ Standards are shown in Table 2 below. (Nitrogen dioxide and sulfur dioxide are
components of NOx and SOx, respectively.)
Table 2. Primary and secondary average concentrations limits on NAAQS criteria pollutants
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Las Vegas Valley Air Quality Index: The U.S. EPA Office of Air Quality Planning and Standards
(OAQPS) in Research Triangle Park, NC supports a website (www.airnow.gov) that provides
current air quality index (AQI) values for many parts of the US, including the Las Vegas Valley.
This resource describes current air quality status and provides parameter values for current
concentrations of NAAQS pollutants of concern, and especially those that are mainly
responsible for the current AQI. Particulate and ozone are often the constituents that drive the
AQI in Las Vegas. Figure 1 and Figure 2 below are screenshots from www.airnow.gov.
Figure 1 Screenshot of the AirNow website for the Las Vegas area on February 25, 2014 showing areas
of both good and moderate air quality in the area around Las Vegas <www.airnow.gov>
Figure 2 Average air concentrations of NAAQS pollutants that determine the color coded AQI values
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Permitted Maximum Particulate Emissions from the EPR 48 MW Gasification Facility: Air
particulate matter (PM) can be characterized according to particle size. Particles with
aerodynamic diameters up to 10 microns are designated as PM10. Particles with aerodynamic
diameters up to 2.5 microns are designated PM2.5. Particles with aerodynamic diameters less
than 0.1 microns are designated as PM0.1. As shown in Figure 3 on the following page, PM2.5 and
PM0.1 are subsets of PM10, and the mass of all particles up to 10 micron in aerodynamic
diameter is included in the PM10 concentration value.
As a initial means of comparing the maximum ground level concentrations of particulate matter
( PM10 and PM2.5) from the EPR 48 MW facility to existing ambient air PM concentrations in the
Las Vegas Valley, concentrations resulting from the EPR maximum permitted emissions are
shown in the Table 3 below. This table lists the ground level concentrations for PM emissions
from the EPR Facility, as compared to the NAAQ Standards and the GOOD DAY AQI values for
the Las Vegas Valley (Figure 1). The fraction of the NAAQS values represented by the maximum
ground level concentrations of PM from the EPR facility are also shown.
Table 3 Ground level concentrations for PM emissions from the EPR Facility, as compared to
the NAAQ Standards and the GOOD DAY AQI values for the Las Vegas Valley
Criteria HAPs
NAAQS
Standard
(ug/m3)
LV Good AQI Day EPRLV Max
Value
Ground Conc.
(ug/m3)
(ug/m3)
Maximum
Fraction of
Standard
PM (TSP)
35
< 54
<0.05
0.001
PM 10
35
<54
0.03
0.0008
PM 2.5
12
<12.4
<0.03
0.0024
In the following section, PM concentrations attributable to the EPR are compared to current
measured ambient levels of these particulates at specific sites in the Las Vegas area, including
two middle schools, Las Vegas City Center, along East Charleston Ave, a four lane arterial road.
In addition, sources of the particulate found in the vicinity of the proposed EPR site are
identified and their contribution to local air particulate matter concentrations is provided from
estimates based on direct measurements.
Ambient Air Particulate Matter in the Las Vegas Area
A primary determinant of air quality in the Las Vegas Valley is airborne particulate matter,
which arises from a number of sources. The relative contribution of each source in a given area
depends mainly on geographical proximity to that source and weather conditions (mainly
atmospheric stability a determined largely by surface level wind velocity and direction).
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Among the important sources of fine (PM2.5) particulate, as measured in air quality studies in
the Las Vegas area, are exhaust from gasoline and diesel powered motor vehicles. As described
below vehicle exhaust includes nitrogen and sulfur oxides and non methane hydrocarbons that
can give rise to secondary particles and eventually react with sunlight to form smog). Tire and
break wear on paved roadways, burning of wood in residential fire places, and disturbed bare
land and pollen from plants and trees can also be sources of airborne PM2.5 and PM10 .
Figure 3 below shows the size range designations (e.g. PM10, PM 2.5 and PM 0.1 ) for air
particulate and indicates the most likely sources and compositions of airborne particles in the
various size ranges. As indicated, other general designations such as course, fine and ultrafine
are also used to distinguish particles according to their size.
Figure 3 Particulate matter designations according to aerodynamic diameter in microns
Particulate Emissions from Bare Land: Due in part to the dry climate, and the amount of
exposed land with little natural vegetation, much of the particulate that would normally remain
on the ground in other environments is readily picked up by the wind and becomes airborne in
the Las Vegas Valley. Air particulate concentrations at ground level due to emission (designated
as crustal or soil particulate) from bare land at wind speeds over about 15 -20 mph easily reach
200 – 300 ug/ m3 in the Las Vegas valley under dry conditions (See Figure 5 below).
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Suspension rates for soil and other particulates into the air from bare land has been measured
at approximately 1 kg/hr per acre at wind speeds of approximately 20 mph or more. During
windy conditions, bare land in the vicinity of the EPR Facility gives rise to ground level air
concentrations of particulate matter that will reach more than 6,000 times those from the EPR
facility. Shown below in the Images below are the visual effects of windblown dust, mainly
classified as PM10 (Figure 5) and stagnant air smog (Figure 6), which is comprised mainly of fine
carbon particles and secondary accumulated fine particles including sulfates and nitrates and
photochemical reaction products (See below)
Figure 5 Airborne dust mainly from bare land on a windy day in Las Vegas
Emissions from Motor Vehicles: Motor vehicles are a major source of particulate matter, with
gas and diesel engine exhaust being the major source of PM 2.5 in most areas and under most
conditions in the Las Vegas area.
As shown below, typical air concentrations of particulates from motor vehicles are in the range
from approximately 5 ug/m3 to more than 20ug/m3 in sampling studies carried in the Las Vegas
area. These particles, especially from diesel engines, are of significant health concern, because
they are typically carbon particles coated with condensed organic species and are of a size that
allows them to be deposited in the deep lung. Soluble constituents can be absorbed into the
circulation where their concentrations can be measured. Under certain other weather
conditions such as thermal inversions, small particles remain suspended in the air and can be
acted on by sunlight to generate photochemical smog of the type visible in Figure 6 below.
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Figure 6 Smog comprised mainly of PM2.5 particulate under stagnant air conditions in Las Vegas.
Emissions from Burning of Wood and Vegetative Material: Burning of wood and vegetation is
another important source of PM in Las Vegas. These particles arise mainly from the combustion
of wood in residential fireplaces, and can also result from range and forest fires. As described
below, these particles can be distinguished from those arising from diesel exhaust, for example,
and can constitute a significant fraction of the suspended particulate in residential areas under
stagnant air conditions, especially in winter time.
Ultrafine and Nanoparticle Emissions: Nanoparticles are products of combustion, including in
internal combustion engines, the source to which most attention in this area has been directed
(Kettleson, 2001). Regulations of nanoparticle emissions are now included within the PM 2.5 air
quality standard. However, more stringent regulations on particles under 100 nanometers
(under 0.1 micron, designated as PM 0.1) are being contemplated by the USEPA.
There has been growing recognition over the last decade or so that the PM 10 and PM 2.5
standards for particulate emissions may need to be updated to specifically regulate particles
with an aerodynamic diameter of less than 0.1 micron. The main source of concern here is
internal combustion engines, which emit combustion products and to which large populations
are routinely exposed. Engine particulate emission standards are mass based.
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Recently, however, interest in other parameters such as particle, size, number, or surface area,
has increased. In anticipation of these new EPA standards, the EPR Facility plans to install high
efficiency electrostatic precipitator (ESP) unit. Such units are capable of removing from 99 to99.99% of particles in the size range from 0.01 to 100 microns (IEA, USDOD, 2004).
Air Particulate Concentrations Measured in the Las Vegas Area
Under the NAAQS, applicable ground particulate matter concentrations standards for the EPR
gasifiers are 35 ug/m3. As determined by USEPA approved AERMOD modeling, ground level
particulate concentrations as a result of operation of these gasifiers will not exceed 0.03ug/m3
(approximately one thousand times lower than the standard.). To obtain a perspective on the
environmental impact of these particulate concentrations, it is instructive to consider ground
level concentrations of various particulates as measured at several sampling sites around Las
Vegas.
Shown below in Figure 7 are the results from measurements made along East Charleston Ave, ,
a four lane arterial with traffic volume and density roughly comparable to that of Craig Ave.
Details as to the sources of the particles collected are shown on the graph. Figure7 shows the
concentration, composition, and probable source of PM 2.5 particulate measured along East
Charleston. Not surprisingly, motor vehicles and bare land (exposed soil) were the main sources
of particulate, total concentrations of which ranged up to more than 40 ug/m3 .
Figure 5. Results from air particulate concentration measurement along East Charleston in La Vegas
(from Desert Research Institute, 2007)
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Figure 8 below shows the portion of the air particulate (as determined by optical extinction or
opacity) along Charleston Ave., which represents a local increase over what could be considered
"background". This increase is due mainly to greater local motor vehicle traffic volume, as
compared to a less populated area represented by Jean.
Figure 8. Comparison of organic compounds from motor vehicles (OMC), elemental carbon
(EC), SO4, NO3 and fine soil and course soil particulates as measured along Charleston Ave. as
compared to Jean. (from Desert Research Institute, 2007)
Air Particulate Measurements at Las Vegas Schools: A study carried out by the Desert Research
Institute (2007) provided direct measurements and characterization of particulates at several
sampling sites in the Las Vegas, North Las Vegas and Jean. Among the sites at which sampling
was carried out were two schools (William E. Orr Middle School and J.D. Smith Middle School).
In this study, particulates collected at the sampling sites were characterized as to their
composition and probable source.
Shown below in Figures 8 and 9 are the results from particulate collection and analysis carried
out at the two Middle Schools (Desert Research Institute, 2007). It is evident from the data that dust
generated on paved roads, including particles from tire and brake wear, was consistently
present as a significant portion of the total particulate. Particles from gas powered vehicles was
also made up a significant portion of the particulate on each measuring day. Figure 9 shows
data from particulate measurements at the J.D. Smith Middle School. Of particular interest here
is the large contribution from the burning of wood in home fireplaces (green segment
representing more than half the airborne particulate) in measurements taken on January 4. It is
interesting to note that if the particulate contribution from the EPR facility were plotted the
graphs in Figures 8 and 9, it would not be visible above the x-axis line.
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Figure 8. Results from air particulate concentration measurement at Orr Middle School
Figure 9. Results from air particulate concentration measurement at JD Smith Middle School
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In other words, at a ground level concentration of 0.03 ug/m3, the presence of the EPR facility
would al not be detectable by measurements of the particulates collected for this study.
Figure 6 below depicts the major sources of particulate material in the vicinity of the proposed
EPR facility. These major sources are outlined in red and include more than 100 acres of bare
land, the I-15 Freeway and Craig Ave.
Figure 6. Major sources of airborne particulate matter in the vicinity of the proposed EPR Site
Assuming that the particulate concentrations in the air of the Las Vegas valley reported by the
USEPA as reflected on the Air Now website are accurate, and that concentrations measured at
two schools, are accurate, it is clear that local particulate concentrations are along a four lane
arterial in Las Vegas, and along freeways such as I-15, would far exceed any from EPR.
To conclude this brief discussion of airborne particulate in the Las Vegas area, below are several
conclusion taken directly from the Southern Nevada Air Quality Study – Final Report (2007)
that are pertinent to the issue of airborne particulate sources and concentrations:
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





The most abundant chemical species were carbonaceous compounds (organic matter)
which comprised more than 80% of PM 2.5.
Chemical analysis of aerosol filter samples collected with the in-plume system indicated
that as much as 50–60% of the PM2.5 is composed of geologic material (i.e., oxides of
Fe, Al, Si, Ca, and Ti), and secondary aerosols of ammonium bisulfate ([NH4]·HSO4) and
NH4NO3.
The contribution of paved road dust to both OC and EC was 5% to 10% at the four sites.
On-road diesel vehicles contribute 22% of the organic carbon and 34% of the elemental
carbon measured at City Center, which is located immediately downwind of US-95.
The contribution of on-road diesel vehicles to haze decreased 50% as the distance
between the source (US-95) and receptor increases (i.e., from the City Center site to the
J.D. Smith School site).
Residential wood combustion is a more important contributor at the East Charleston
and Orr Middle School sites than on-road diesel vehicles, probably due to their
residential neighborhoods.
Comparison of Permitted Emissions with Ambient Levels of Other NAAQS Pollutants
Aside from particulates, which are of primary concern with regard to air quality in Las Vegas,
there are number of other NAAQS criteria pollutants for which regulatory concentrations have
been set by the Clean Air Act. These additional constituents, designated as Hazardous Air
Pollutants, or HAPs, are listed in the left hand column of Table 4 and below .. Also provided in
Table 4 are the applicable NAAQS standards and the maximum ground level concentrations due
to operation of the EPR.
Table 4 Maximum round Level concentration for NAAQS criteria pollutants other than PM
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Comparison of NOx Emissions with those from a Local Clean Natural Gas Power Plant
As an example of the relative environmental impact of the EPR Facility in terms of NOx
emissions, AERMOD modeling of EPR emissions allows several comparisons with current air
quality in the general area. The major source of NOx in the area is the SWG gas turbine power
plant located on Alexander Street. As shown in Figure 10, NOx concentrations inside the EPR
facility perimeter are strongly influenced by the SWG facility located approximately two miles
away. The additional contribution of the EPR plant to the NOx concentrations in the area is
negligible in comparison with those from the SWG power plant. In addition, the combined NOx
concentration in or near the perimeter of the EPR facility will, in no case, exceed applicable
NAAQS standards. In fact, they will remain between 90% and 95% below applicable standards.
Figure 10. Maximum one-hour NOx concentrations, in parts per billion (ppb), as predicted by AERMOD.
The plot is centered on the NV Energy facility. The increased NOx concentration to the southwest is due
to the SWG Nevada generating station. Scale is shown on lower left (color concentration scale is in ppb).
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Figure 11 shows the ground level concentrations of NOx in the vicinity of the proposed EPR
facility in greater detail. Again, these concentration isobars were generated by AERMOD using
the maximum permitted emissions from the SWG combustion turbine power plant. These data
show that the major source of NOx in the area of the proposed EPR Facility is the combustion
gas turbine plant located more than a mile away. The footprint from the EPR plant can be seen
as the wedge shaped area of 1.8 to 2.1 ppb in the upper right hand quadrant of the grid.
Figure 11. Maximum one-hour NOx concentrations, in parts per billion (ppb), as predicted by
AERMOD. The plot is centered on the location of the proposed stacks. Maximum NOx concentrations
were found to the Northeast and Southwest of the site. Scale is shown on lower left (color concentration
scale is in ppb). .
Nitrogen oxides and non-methane hydrocarbons come mainly from automotive exhaust, and
are of primary concern with regard to air quality because they react with sunlight to form
photochemical smog. The sequence of these mainly photo-driven reactions is complex, but
proceeds roughly as follows: 1) Nitrogen oxides generate oxygen atoms, 2) These oxygen
atoms form hydroxyl radicals, 3) Hydroxyl radicals generate hydrocarbon radicals, 4)
Hydrocarbon radicals form hydrocarbon peroxides, 5) Hydrocarbon peroxides form aldehydes,
6) Aldehydes form aldehyde peroxides, 7) Aldehyde peroxides form peroxyacylnitrates. The
latter substances in this reaction sequence are the compounds that irritate sensitive biological
tissues and cause most of the health problems associated with photochemical smog (Faust,
2014).
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National Emissions Standards for Hazardous Air Pollutants Criteria Pollutants
In addition to the criteria pollutants regulated under NAAQS, a number of additional pollutants,
known or suspected to be hazardous in sufficient concentrations in the environment, are also
regulated under the National Emissions Standards for Hazardous Air Pollutants, or NESHA.
The standards for regulating a particular source of these constituents require the maximum
degree of emission reduction that the EPA determines to be achievable by best available
technology. This type of regulation is referred to as the required application of Maximum
Achievable Control Technology, or MACT.
Among the constituents that must be controlled to MACT levels under NESHAP are several
members of a class of compound known as volatile organic compounds, or VOCs, including
dioxins and furans. Toxic metals, including mercury and cadmium, are also regulated according
to MACT. (Thus, in Table 5, no numbers are shown NAAQS or Maximum Fraction columns.)
Among the toxic metals, mercury is of the greatest concern once released into the
environment, where it undergoes chemical reactions that allow its bioaccumulation in plant
and animal tissues. Mercury emissions from ordinary incinerators can come from mercury
containing materials such as fluorescent light bulbs, small electronic device batteries and
electrical switches in the waste stream.
No mercury containing waste materials are anticipated to be present in the waste stream
entering the EPR Facility. Any mercury containing waste that is found in the waste stream will
be removed and stored in a secure are for eventual disposal in a landfill. As shown in Table 5,
maximum mercury emissions will remain well below the detection limit of the monitoring
equipment used to detect it in the stack gas from the EPR Facility. Therefore, for all practical
purposes, mercury emissions from the facility will be essentially zero.
Table 5 Maximum ground level concentrations of MACT regulated constituents of interest
Dioxins and furans are trace products of the combustion process. As a class of chemicals, they
comprise more than 200 separate compounds with widely varying toxicities. As combustion
products, these compounds are generated by everything from fossil fuel combustion in motor
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vehicles (especially diesel trucks), to natural gas and coal fired power plants, burning wood in a
fireplace, and even the burning tobacco in cigarettes. The USEPA strictly regulates the amount
of dioxins that can be released into the atmosphere by cars, trucks and power plants, and has in
recent years encouraged the banning smoking in public buildings.
Data from operating waste to energy gasification facilities, using only a baghouse for flue gas
clean up, show that dioxins in the flue gas typically remain below the level of detection. As
described below, the flue gas clean-up train used with EPR gasification systems includes a
Cyclone, a Dry Scrubber (Acid Gas Removal Unit), Selective Catalytic Reduction (SCR) Unit, and
an Electrostatic Precipitator (ESP) unit, as well as a baghouse with carbon injection on each 12
MW line. This five component flue gas clean-up system allows the EPR gasifiers to far exceed
the requirements for dioxin and furan removal by the USEPA. Just as importantly, the
temperature regimes and availability of oxygen for combustion throughout the process will be
controlled to minimize the formation of these compounds in the first place.
Incremental Health Risk
Results from studies that look at the relative health risk of air pollution, and specifically
particulate matter, can be used In assessing the environmental impact and potential
incremental health risk of the EPR facility. As described by the USEPA, NAAQ standards are set
at levels believed to be safe, even for sensitive individuals such as the elderly or the every
young. Thus, upper limits on the concentrations of the NAAQS criteria pollutants are have been
set to be well below those that would represent a threshold for the onset of adverse health
effects in the overall population.
In large independent studies on the health effects of ambient PM2.5, the threshold for adverse
health effects from causes other than cardiovascular-respiratory disease, was approximately 50
ug/m3. For cardiovascular-respiratory causes, the preferred model for assessing incremental
risk was characterized approximately linear with no threshold for ambient PM2.5 (Brugge, 2007).
Historic annual averaged particulate matter numbers in US cities considered in the study range
between approximately 6 and 12 ug/m3, with a weighted average ranging between
approximately 3.5 and 5.5 ug/m3. With a maximum PM2.5 stack emission concentration at
ground level of less than 0.03 ug/m3 it is reasonable to claim that, on average, ground level
concentrations of particulate matter in gasses emitted from the stack will be lower than those
in the ambient air around the stack.
Thus, even using a linear no threshold model for incremental health risk from particulate
matter, the EPR facility must be seen as a protective factor as opposed to a risk factor in terms
of particulate matter emissions.
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Comparison of EPR Environmental Impacts with the Alternatives for Solid Waste Disposal
When considering the potential environmental impact of the EPR facility, it is reasonable to ask
how its operation compares with the impact of available alternatives for disposal of solid waste
and generation of electrical energy. These alternatives are discussed below.
Recycling: Recycling is the preferred means of diverting waste from landfills, and recycling is an
integral component of the EPR operation. However, not all waste is recyclable, either because it
is impractical to separate certain components from the bulk raw waste stream, or no market
exists for such materials. Such non-recyclable materials are often designated as residues or
discards, and are normally disposed in landfills.
Disposal in Landfills: In 2009, the USEPA signaled its increasing concern with the long term
effects of greenhouse gasses from municipal solid waste landfills (Thorneloe, 2012) . The EPA
cited studies showing that thermal waste to energy conversion is between two and six times
more efficient in converting solid waste to energy as compared to disposal of "as-collected"
solid waste in landfills with landfill gas recovery. The EPA noted that landfills can emit
greenhouse gasses, as well as other criteria pollutants, from the decomposition of waste for as
much as 50 years after it is disposed. As one researcher put it, "Landfills are forever".
Figure 13 below compared the landfill, incineration disposal options to air fed gasification in
terms of greenhouse gas equivalents and NOx, SOx and particulate emissions, in terms of
emissions per kWh of electrical power generated.
Fig.13 Comparison of (left) carbon dioxide equivalents and (right) NOx, SOx and particulate emission. per
kWh generated by landfill gas capture, incineration and gasification waste to energy conversion plants.
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With regard to particulate and NOx emissions, it should also be noted that the EPR Facility will
reduce the consumption of diesel fuel, which would otherwise be used in hauling the waste to
the APEX landfill, by a substantial amount. Not only are the savings in fuel significant, the
reduction of truck miles represents an associated reduction in particulate, both from the
burning of this fuel in the Las Vegas Valley, and from the reduced particle emissions associated
with tire wear and fugitive dust from the trucks at highway speeds. Table 6 shows the reduce
fuel use and associated reduction
Table 6. Comparison of Carbon Dioxide Emissions from
in greenhouse gas emission that
Motor Vehicles Transporting Waste and Personnel to Apex
will be realized from hauling of
Landfill as compared to the New EPR Facility
waste from the North Las Vegas
area to the EPR Facility instead
of the APEX landfill. As shown in
Table1, locating the EPR Facility
on Lone Mountain Road will
lower carbon emissions by some
2,000 tons per year from
reductions in diesel consumption
alone, as compared to hauling
the waste to the APEX Landfill.
When one considers the
greenhouse gas equivalents
produced by a land filling, the
additional criteria pollutants produced by the truck traffic to and from the Apex Facility, and the
combustion of coal to generate the power not generated by the EPR Facility, EPR can be shown
to contribute to a net improvement in the environment.
New legislation in the European Union (EU), which (of necessity) is now well ahead of the US in
many ways when it comes to solid waste management, will no longer allow for any gasproducing wastes to be placed into landfill. Integrated waste management systems in the EU
now call for mandatory recycling, combustion of gasification of discards or residues, and the
landfilling of only inert ash or other inorganic wastes. One strong motivation for this innovation
in waste management is that waste volume is reduced by up to 90%, as compared to waste
management practices in the US.
In 2009, the EPA noted that, while the amount of MSW generated in the US had doubled since
the 1970s, green house gasses from municipal solid waste (MSW) has decreased significantly
because of programs to improve collection, recycling and discards management. Such programs
included landfill gas collection and the increased use of direct thermal conversion of MSW.
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In terms of discards management, that is management of materials that cannot be recycled, the
EPA reports that direct thermal conversion (combustion or gasification) is, on average, six to
eleven times more efficient in recovering energy from waste than landfills.
EPR Waste to Energy Gasification is a Clean Air Technology
Any number of studies, including those carried out by the USEPA (1996) and the USDOE (2002),
as well as reports from Los Angeles (URS, 2005), Victoria, BC (Stantec, 2011), and BPA (2009)
and a large study from Europe (Munster, 2009), show that properly designed and operated air
fed gasification systems are, by far, the most efficient and cleanest technologies for converting
solid waste to energy.
EnviroPower Renewable works with equipment manufacturers and operators to design the
cleanest air fed gasification systems available. Designing for clean operation starts with the
procedures used to collect and separate the refuse derived fuel that will be used in the
gasification systems, and continue through the thermodynamic design of the facility and
selection of stack gas cleaning equipment.
Recycling: Any materials that can be sent to economically viable recycling market will be removed
from the waste stream and recycled. In fact, the waste materials are first sorted and recycled at
an offsite Material Recovery Facility (MRF), and then are again sorted, and recyclables and
unacceptable waste are removed at the EPR Sorting Facility. The only materials that will be
gasified are combustible residues from the sorting lines that have no value as recyclable
materials, or for which no viable market exists.
Fuel Selection: Refuse derived fuel (RDF) is generated by sorting the incoming waste streams
and removing recyclable materials, non-combustible materials (also known as inerts), and any
hazardous materials or wastes that might generate materials during the gasification process.
Characteristics of the RDF that is used in the facility are highly dependent on the incoming
waste stream. The fuel selection, fuel feed rate and under fire air feed rate are computer
controlled to maintain optimal temperature and oxygen partial pressure inside the gasification
reactor. More important is the fact that the EPR.
Odor and Fugitive Dust: The EPR facility will only accept dry combustible materials, as
contained in construction as demolition waste and source separated commercial waste. These
materials are comprised mainly of wood, plastics, cardboard and paper, carpeting, roofing
material, with minor amount of leather, textiles, and other fiber materials. No odor causing
materials such as food or kitchen waste is accepted. For this reason and because all operations
will be conducted inside a building at negative pressure, The EPR facility will not be a source of
odor of fugitive dust emission.
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Hot Cyclone: A hot cyclone is installed directly after the gasification reactor to remove most
particulate before it enters the fuel gas burner, which is operated in such a way to avoid the
formation of NOx. Hot gases entering the boiler from the fuel gas burner are controlled to a
temperature that is below the melting point of any remaining particulate material to prevent
fouling of the boiler tubes and maintain the efficiency and reliability of the steam boiler.
Flue Gas Clean-up Process Units: Flu gas from the boiler is then routed through a series of
process units to neutralize or remove remaining particulates or criteria pollutants. These units
include a dry scrubber to remove any acid gas residues including SOx and traces of HCl. The dry
scrubber is followed by an selective catalytic reduction (SRC) unit that provides a reagent and
catalyst that promotes a reaction with any remaining NOx to convert it to molecular nitrogen
(N2) and water. Any remaining particulate in the flue gas at this point is removed by a high
efficiency electrostatic precipitator (ESP). The ESP unit is followed by a fabric filter baghouse,
into which activated carbon is injected to absorb any traces of organic molecules remaining in
the gas stream. The baghouse also serves as a final filter for any particulate that has not already
been removed by the ESP.
The flue gas clean up units incorporated into the EPR gasification systems, including a cyclone,
dry scrubber, selective catalyst reduction (SCR) unit (for NOx abatement) fabric filter
(baghouse) with carbon injection, and high efficiency electrostatic precipitator will remove
approximately 99% of the material with a mean particle size of 1 micron and approximately
95% of the particles with a mean size of 0.1 microns. It should be noted that, at the present
time, there is no reliable method for measurements of nanoparticles with aerodynamic
diameters of less than 0.01 microns in diameter that would allow for enforcement of new
regulations on particles of this size.
The combined and sequential action of these flue gas clean-up process units means that, as
shown in Table 1, the gas leaving the EPR facility will be, on average, much cleaner than the
ambient North Las Vegas air that enters the facility in terms of ground level concentrations the
NAAQS and NESHAP criteria pollutants than the average ambient air in the Las Vegas Valley.
_______________________________
Final Notes:
1. References used in this white paper have been selected from those readily available on the internet
so that the reader can easily access source information (URLs are provided for all reverences.).
2. EPR gasification systems are specifically designed for the environment in which they will be operating.
The specific equipment described in this white paper is available on the EnviroPower Renewable
systems, but may or may not be used in the EPR facility.
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References
Brugge, D. et al (2007) Near-highway pollutants in motor vehicle exhaust: A review of epidemiologic
evidence of cardiac and pulmonary health risks Environmental Health 2007, 6:23
http://www.ehjournal.net/content/6/1/23
Clark County DAQ, (2012) Redesignation Request and Maintenance Plan for Particulate Matter (PM10)
Clark County, Nevada
http://www.clarkcountynv.gov/Depts/AirQuality/Documents/PM10%20Plan%202012.pdf
Desert Research Institute (2007) Southern Nevada Air Quality Study – Final Report FTA-NV-26-70032006.01 (February 2007)
http://www.fta.dot.gov/documents/Desert_Research_Institute_Final_Report.pdf
Faust (2014) http://mtweb.mtsu.edu/nchong/Smog-Atm1.htm
IEA Electrostatic Precipitators
http://www.iea-coal.org.uk/site/ieacoal/databases/ccts/electrostatic-precipitators-esp
BPA (2009) Evaluation of Emissions from Thermal Conversion Technologies Processing Municipal Solid
Waste and Biomass: Final Report (2009) Bioenergy Producers Association
http://socalconversion.org/pdfs/UCR_Emissions_Report_62109.pdf
Kaplan. PO, et al; Is It Better to Burn or Bury Waste for Clean Electricity Generation? Environ. Sci.
Technology, 2009, 43, 1711-1717. http://pubs.acs.org/doi/abs/10.1021/es802395e
Kettleson, DB (2001) Recent Measurements of Nanoparticle Emissions from Engines
http://www.me.umn.edu/centers/cdr/reports/JAASTpaper.pdf
Münster, M (2009) Energy Systems Analysis of Waste to Energy Technologies by use of Energy PLAN,
Danish Technical Research Counsel; ISBN 978-87-550-3719-9
http://www.wtert.com.br/home2010/arquivo/noticias_eventos/ris-r-1667.pdf
URS (2005): Summary Report: Evaluation of Alternative Solid Waste Processing Technologies. City of Los
Angeles Dept of Public Works. Prepared by URS Corporation, Los Angeles, CA.
http://www.lacitysan.org/solid_resources/strategic_programs/alternative_tech/PDF/summary_report.pdf
Stantec (2011): Waste to Energy: A Technical Review of Municipal Solid Waste Thermal Treatment
Practices Final Report (2011) Environmental Quality Branch Victoria BC
http://www.env.gov.bc.ca/epd/mun-waste/reports/pdf/BCMOE-WTE-Emissions-final.pdf
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Thorneloe, SA (2012) U.S. Trends in Solid Waste Management and GHG Emissions Health and
Environmental Concerns for Landfills ,Berlin Germany
http://www.umweltbundesamt.de/sites/default/files/medien/421/dokumente/us_epa_swm_and_ghg_
emission.pdf
USDOE (2002): Gasification Markets and Technologies – Present and Future: An Industry Perspective
USDOE Report DOE/FE-0447 http://www.docstoc.com/docs/629501/Gasification-Markets-TechnologiesPresent-and-Future-An-Industry-Perspective-July
USEPA (2009) Gasification and Renewable Energy
http://www.epa.gov/osw/hazard/wastemin/minimize/energyrec/renew.htm
WA-RD (1002) Analysis of particulate matter dispersion near urban roadways
http://www.wsdot.wa.gov/research/reports/fullreports/262.2.pdf
__________________________________________________________________________________
Author Contact Information:
Bary Wilson, Ph.D.
[email protected]
Phone: 954 683 8706
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