Research Policy 43 (2014) 1816–1826
Contents lists available at ScienceDirect
Research Policy
journal homepage: www.elsevier.com/locate/respol
The evolution of waste into a resource: Examining innovation in
technologies reusing coal combustion by-products using patent data
Joo Young Park ∗
Center for Industrial Ecology, School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT 06511, United States
a r t i c l e
i n f o
Article history:
Received 19 February 2013
Received in revised form 6 November 2013
Accepted 10 June 2014
Available online 1 July 2014
Keywords:
Waste reuse
Technological innovation
Patent count
Coal combustion by-product
Fly ash
Bottom ash
a b s t r a c t
The reuse of waste begins with the development of new technologies for ways to use waste. Despite the
critical role of innovation in waste reuse, innovation for waste reuse technologies has been largely overlooked in innovation studies. This paper presents the first patent study examining the innovation process
for a specific waste reuse technology, to elucidate how waste evolves into a resource with a greater possibility of being used. This study specifically analyzes how innovation occurs, what drives it, and the
consequences of this innovation. Coal combustion by-products (CCBs), which are solid residues generated from coal-fired utilities, are specifically examined as a test case because they have been promoted as
a resource through century-long innovative efforts for use in construction, mining, and agricultural applications. Having examined more than 700 patents from the United States Patent and Trademark Office
database, the results of this study show that innovation has primarily occurred: (1) to reuse CCBs, particularly fly ash, in various building, construction, and structural products; (2) by businesses, particularly
those that need to use CCBs; and (3) since 1967, and the number of CCB-related patents peaked during
the early 1980s and 1990s. For the drivers of innovation, this study identifies the impact of some market
factors, such as cement and lime price, and institutional activities, such as the establishment of industrial
associations that support CCB reuse, on patent filings. The role of regulation in innovation, however, is
ambiguous with regard to CCB reuse. Although more CCBs have been used as more innovation occurs,
the use of CCBs has increased with a lag, due to variation in the values of individual technologies and
barriers to the implementation of technologies in the reuse market.
© 2014 Elsevier B.V. All rights reserved.
1. Introduction
Technology governs the life cycle of materials with regard
to how they are mined, manufactured, used, and discarded. The
interplay between technology and materials, however, is not well
understood in the case of waste. Waste exists in the anthroposphere, often without the appropriate technology to use it, which
is different from natural resources that are extracted according
to the available technology. Taking no actions for waste bears
costs to society and the environment, because discarding waste
increases the anthropogenic disturbance when it is either landfilled
or released back to nature. The alternative way, recycling and reuse
of waste, requires the development of appropriate technologies
that make reuse possible. Along with new knowledge about where
and how to reuse waste materials, the hidden value of these materials have started to be recognized (Park and Chertow, 2014). This
∗ Tel.: +1 203 432 4985; fax: +1 203 432 5556; mobile: +1 475 201 8237.
E-mail address: [email protected]
http://dx.doi.org/10.1016/j.respol.2014.06.002
0048-7333/© 2014 Elsevier B.V. All rights reserved.
innovation process requires skills that are sometimes more creative
than the original production process because reuse opportunities
need to be explored given specific characteristics of the material
(Reno, 2009). Therefore, innovation is a pre-requisite for facilitating waste reuse and forms a basis for the sustainable materials
management that is envisioned by the United States Environmental
Protection Agency (USEPA, 2003, 2009) and the concept of industrial ecosystem that has closed-loop material flows (Frosch and
Gallopoulos, 1989; Graedel and Allenby, 2003).
Despite the importance of innovation in waste reuse, no previous studies have examined the innovation of a specific waste reuse
technology. Only a few studies briefly examined the patent data
for waste management, which includes disposal, incineration, and
recovery, or waste recycling as a single component within a larger
group of environmentally responsible technologies (Johnstone
et al., 2010a; OECD, 2008). Instead, studies have focused on emission control technologies (Popp, 2003, 2006, 2010; Taylor et al.,
2003), climate change mitigation technologies (Dechezleprêtre
et al., 2011; Haščič et al., 2010), renewable energy technologies
(Johnstone et al., 2010b), and technologies for green chemistry
J.Y. Park / Research Policy 43 (2014) 1816–1826
(Nameroff et al., 2004). Other studies have examined innovation
as conditions of waste reuse or consequences thereof, but those
studies addressed innovation in a broader sense by encompassing social, organizational, behavioral, and institutional dimensions
(Boons and Berends, 2001; Harris and Pritchard, 2004; Mirata and
Emtairah, 2005). Therefore, these studies lack a specific focus on
technological innovation, how it occurs, what drives it, and its consequences.
Because of the lack of studies regarding the role of technological innovation in waste reuse, this is the first study to empirically
examine the innovation patterns and processes of a waste reuse
technology. It first identifies the patterns of innovation by counting
the number of successful patent applications, and then discusses
the underlying causes and effects of innovation. For driving forces
behind innovation, it investigates relevant regulatory actions, institutional activities, and economic factors in relation to patterns of
patent filings. To examine the consequences of innovation, patent
patterns are compared to the amount of waste that is actually
reused. A detailed study of innovation for a waste reuse technology
can advance understanding of environmental innovation, particularly by investigating its unique characteristics compared to other
environmental innovations.
Coal combustion by-products (CCBs) are selected for the empirical portion of this study. CCBs refer to several types of solid residues,
such as fly ash, bottom ash, boiler slag, flue-gas desulfurization
residues, and fluidized bed combustion ash, which are generated
during coal-fired electricity production. Fly ash is a fine particulate
captured by particulate control equipment, whereas bottom ash
and boiler slag are coarser and heavier fractions that are collected
at the bottom of the furnace. Bottom ash consists of porous particles
that have fallen from pulverized dry-bottom boilers, and boiler slag
comes from pulverized wet-bottom boilers (slap-tap furnace) or
cyclone boilers where it is quenched with water and fractures into
an angular, glassy slag (EPRI, 2009; Pflughoeft-Hasset et al., 1999).
Different types of flue-gas desulfurization (FGD) residues are generated from a sulfur dioxide scrubbing process depending on the
type of sorbent used, the extent of oxidation, and post-scrubbing
processes including dewatering, drying, and blending (Kosson et al.,
2009). FGD gypsum is formed when wet residues from limestonebased scrubbing process are subject to forced oxidation (Ward,
2010). Fluidized bed combustion (FBC) ash collectively refers to
the fly ash and bed ash generated by a FBC boiler in which a
mixture of coal and a sorbent such as limestone is fluidized by
combustion air that is forced upwards. CCBs have evolved from
materials that were mostly discarded in the 1930s, to materials
that are reused more and more often, through the development of
reuse applications over a century. Some countries, such as France,
Germany, South Korea, and the Netherlands, were reusing greater
than 90% of the fly ash, bottom ash, and boiler slag during the
late 1980s and early 1990s (Manz, 1997). Recent statistics showed
that Japan and 15 countries in Europe reused more than 96% and
89% of CCBs, respectively (European Coal Combustion Products
Association, 2008; JCOAL, 2009). Therefore, CCBs can be seen as a
category that straddles the boundary between what is defined as a
waste and what as a resource, thus provide an interesting example
at the interface where technology meets waste.
1817
technologies to economize the use of input factors (Hicks, 1932).
Porter has also argued that regulation can increase profits while
inducing R&D investment because innovation that involves a high
degree of uncertainty is not the result of an optimization process (Porter and van der Linde, 1995). When addressing the
effect of regulation on innovation, regulatory stringency, which
is often measured by pollution abatement expenditures, has been
of interest (Brunnermeier and Cohen, 2003; Lanjouw and Mody,
1996; Pickman, 1998); however, increasing focus has been placed
on the different forms of regulation (Jaffe et al., 2002; Magat,
1979). Compared to direct command-and-control type regulations,
market-based instruments are known to often be more effective
for encouraging the adoption and diffusion of new technologies.
For example, Popp (2003) empirically showed that trading of
sulfur dioxide allowances under the 1990 Clean Air Act led to
more environmentally-friendly innovation in scrubbers. The strong
relationship between regulation and environmental innovation,
however, sometimes makes regulation a major barrier for inducing and adopting environmental technology (Office of Technology
Policy, 1998). Whether regulation acts as a driver or a barrier
for innovation depends on its design and implementation. For
example, the negative influence of regulation can be particularly
aggravated when it is overly unpredictable, prescriptive, and inflexible (Johnstone and Haščič, 2009).
Whereas regulatory pressure has been studied as the primary
determinant of environmental innovation, innovation is also influenced by other factors. It is generally accepted that technology
push factors are particularly important during the initial stage
of innovation, whereas market demand factors are important for
the diffusion phase (Pavitt, 1984). In a case study of environmental product innovation in Germany, price was observed to be
the primary obstacle in the commercialization of environmentally
superior products (Rehfeld et al., 2007). In addition, organizational
measures such as certified environmental management systems
and other firm specific factors, can influence environmental innovation (Horbach, 2008). Different factors may exert different levels
of influence on environmental innovation. In an empirical study,
Cleff and Rennings (1999) observed that environmental innovation
at the product level is influenced more by market factors, whereas
environmental process innovation is influenced more by regulations. They argued that a simplistic regulatory stimulus, such as the
innovation response approach, is not appropriate for addressing all
environmental innovations.
In this study, findings from previous studies are expanded and
built upon, and the innovation for a waste reuse technology, its
patterns, drivers, and consequences, are investigated to determine whether observations of other environmental innovations
are also applicable to waste reuse innovation. Because waste reuse
requires the involvement of diverse actors, such as waste generators, processors, marketers, and users in different sectors of
industry, innovation for a waste reuse technology may have more
complicated underlying drivers. Whereas the role of regulation in
innovation has been examined as a strong driver in the environmental innovation literature, this may not be the case for waste
reuse innovation. Waste reuse and innovation can be influenced by
regulations that support waste reuse, regulations that address the
disposal of waste, and regulations that have an indirect impact on
reuse by changing the quantity and quality of waste.
2. Literature review of environmental innovation studies
3. Methods
The role of government regulation in inducing changes of environmental technology has been a main focus of the environmental
technology literature. This type of research was motivated by
Hicks’ “induced innovation” whereby a change in the relative price
of production factors, which can be influenced by government
interventions, would motivate firms to invent new production
3.1. Data collection and management
To track innovation, particularly invention in CCB reuse technology, this study examined patent statistics. Despite their
shortcomings, patent statistics are the most widely used measure of
1818
J.Y. Park / Research Policy 43 (2014) 1816–1826
innovation in empirical studies due to their accessibility, availability, and the amount of technological and organizational information
that can be derived from these statistics (Griliches, 1990). Patent
data were retrieved from the United States Patent and Trademark
Office (USPTO) patent full-text and image database (USPTO, 2011).
This database provides patent information for patents published
from 1790 to the present. To search for patents that were related
to CCB reuse, several complementary methods were used because
no unique patent classifications are assigned to CCBs other than
fly ash. First, different combinations of keywords were used to
identify patents that were most likely to be related to CCB reuse.
The keywords used in this search were coal ash, coal combustion
product/by-product/waste, pulverized fuel ash, fly ash, cenosphere,
bottom ash, clinker ash, synthetic gypsum, flue gas desulfurization gypsum, boiler slag, slap tap/cyclone boiler/wet bottom ash, fluidized bed
combustion ash, and scrubber sludge. For fly ash, the classification
number was also used in addition to the keywords.
The collected patents were then filtered using the following 9
criteria: (1) include any patent related to the reuse of CCBs, (2)
exclude any patent related to the disposal of CCBs, (3) exclude
any patent related to combustion technologies or pollution control
technologies for coal-fired power plants, (4) exclude any patent in
which the invention does not emphasize the reuse of CCBs but does
emphasize the reuse of other waste products (e.g., if the invention
incorporates CCBs in only a minor fashion or when the use of CCBs
follows already established knowledge or common practice), (5)
exclude any patent if the use of CCBs is optional only, (6) exclude
any patent that enhances the quality of CCBs as a result of improving
process efficiency (e.g., the quality of FGD gypsum is increased as
the efficiency of the desulfurization process increases), (7) exclude
any patent that applies to both synthetic and natural gypsum, does
not differentiate between the two, and ignores differentiation for
the source of the synthetic gypsum (e.g., synthetic gypsum can be
generated from the desulfurization process or from the phosphoric
acid production process), (8) include any patent that targets coal
slag generated from burning coal only but not from coal gasification
or carbonization, such as coke production and coal tar production, and (9) exclude any reissued patent. To filter the data, the
abstract or full patent, if necessary, was read to determine whether
the patented technology facilitated the reuse of CCBs. For example,
a patent for reusing fly ash from municipal solid waste incineration was filtered out. For each patent selected, all patents that
were directly referenced as prior art were reviewed and filtered in
the same manner. The reference check was particularly useful for
searching patents published prior to 1976 because these patents
cannot be searched via key words. Through this iterative search
process, a total of 707 patents, beginning in 1875, were identified.1
For the final list of patents, basic information including the
patent number, date published, date filed, title, abstract, inventors,
and assignees were recorded. Additional features of the patent were
also analyzed and documented. The types of CCBs that were targeted for reuse were classified into the following 6 groups: fly ash,
bottom ash, boiler slag, flue-gas desulfurization gypsum, fluidized bed
combustion ash, and a mixture of these or unspecified types of CCBs.
Reuse applications of CCBs were classified into the following 21
categories: aggregate, agriculture, base, processing, treatment, building/structural/construction materials, cement, concrete, fills, mineral
filler for asphalt, filler, gypsum panel, metal extraction, mining, mineral
wool, pavement, roofing materials, snow and ice control, soil stabilization, waste stabilization, and miscellaneous. “Processing” of CCBs
was included as a reuse category due to its important role in reuse,
even though processing itself does not constitute reuse. These
1
The time period of the search was from 1790 until February 1, 2011.
reuse application categories are more comprehensive than those
of the American Coal Ash Association’s (ACAA) reporting statistics
because additional reuse options were identified during the patent
analyses. Depending on the nature of the invention, one patent may
provide multiple applications for CCB reuse; therefore, more than
two reuse options were sometimes allotted to a single patent.
Assignee information was tracked and classified as business,
research, university, government, individual, and unspecified. The
business category was further classified, if possible, into businesses
that generate CCBs, businesses that act as intermediaries in reusing
CCBs, businesses that incorporate CCBs into production processes,
and businesses that include a research and development department. For example, the first category includes power utilities and
boiler manufacturers, the second category includes CCB marketers,
waste management companies, and consulting companies, and the
third category includes companies that produce cement, concrete,
or building materials. If the type of business could not be identified,
if the business could act both as a CCB generator and user, or if a
business was not directly related to the reuse of CCBs, such as lime
producer, it was assigned to group, labeled “business.” Any corporations with multiple subsidiaries encompassing different sectors
were also marked as a general business category. All patents without designated assignees were categorized as “unspecified.”
3.2. Analysis method
Based on the compiled patent database, three analyses were
conducted. The first analysis examined the nature of CCB reuse
technologies from 1875 to the present by examining which CCB
components were targeted for reuse by which applications and by
investigating what was involved in the innovation.
The second analysis examined the temporal pattern of innovation from 1950 to 2009 by counting the number of patents filed each
year. The timeframe of the longitudinal analysis was truncated to
1950, considering that the patenting activity and major environmental regulations in the United States had occurred after then.
The year filed was used instead of the year published because the
former is more likely to be closer to the time when the innovation
was first organized and developed (Popp, 2003). This temporal pattern was then examined in relation to economic factors, regulatory
actions, and institutional activities to understand the causes of the
historical development of CCB reuse technology.
As economic drivers, the prices of cement, lime, construction
sand and gravel, and gypsum were examined in relation to the temporal pattern of patent filings (Kelly and Matos, 2011).2 CCBs can be
used in place of these natural resources: fly ash can be used in place
of cement or lime, bottom ash can be used in place of construction
sand and gravel, and FGD gypsum can be used in place of natural
gypsum. Therefore, increases in the price of these resources may
drive innovation toward the use of less expensive CCBs instead.
The level of construction activities, in terms of annual value of construction put in place, was also presented to show changes in the
overall demand both for CCBs and their natural substitutes (U.S.
Census Bureau, 1964–2002, 2002–2012). The cost for collecting and
disposing of CCBs was not included in the analysis because it was
difficult to examine its impact on innovation only with several years
of data that were available.
In addition, any federal regulation that has a direct and indirect
influence on CCB use and innovation was documented in terms
of when it was first instituted or proposed. Finally, for the role
of social factors in waste reuse, the institutional environment
was examined as a means to support innovation for CCB reuse.
2
Here, gypsum includes both natural and by-product gypsum.
J.Y. Park / Research Policy 43 (2014) 1816–1826
140
The number of patents
120
100
80
Fly Ash
Mixture or Unspecified CCBs
FGD Gypsum
FBC Ash
Boiler Slag
Bottom Ash
Table 1
Distribution of patents according to the ownership type.
Ownership type
Business
60
40
20
0
Fig. 1. The number of patents classified according to the CCB reuse application categories, and the composition of CCB components that the invented technology aims
to reuse.
Institutional activities such as the establishment of trade associations that have outreach programs, training workshops, and
conferences, research institute that develop reuse technologies, or
standards that approve the use of CCBs in certain applications can
help facilitate the sharing of relevant knowledge and information,
and may provide peer pressure and norms for waste reuse. Relevant institutions and their information were investigated through
various websites and reports, and information about CCB-related
standards was compiled through the search of the American Society for Testing and Materials (ASTM), the National Resource for
Global Standards, American National Standard Institute, and IHS
Standard Store.
In addition to the potential drivers of technological innovation, the implications of these innovations were finally analyzed by
examining the relationship between patent filing and the actual utilization of CCBs. The comparison was made in two different ways:
one across CCB use categories and the other across time. The former
comparison allowed us to examine the varying impact of a group of
technologies for each use application on CCB utilization. Through
the latter comparison, any discrepancy or a lag between the temporal pattern of patent filing and the amount of CCBs used could be
identified.
4. Results and discussions
4.1. The nature of CCB reuse technologies
Fig. 1 indicates the value of CCBs for building-, construction-,
and structural-related products. Among the 707 identified patents,
more than half (395 patents) were targeted toward the use of CCBs
in aggregate, cement, concrete, road base/sub-base, fills, gypsum
panel products, roofing materials, pavement, asphalt, and more
general applications in the relevant industries. The single category
with the largest number of patents (129 patents) was processing
because CCBs need to be treated or processed into an appropriate form before they can be used. For example, residual carbon or
ammonia in fly ash needs to be removed, the size distribution of
ash particles needs to be controlled, and slurry, including FGD gypsum, needs to be oxidized and dewatered. CCBs can also be used to
solidify waste materials to reduce hazards from leaching. Similarly,
CCBs help to stabilize the soil or subsurface to enhance the strength
of a foundation and channel the flow of groundwater. Other CCB use
1819
Research
Academia
Public
Miscellaneous
Generator of CCBs
Intermediary actor for
CCB use
User of CCBs
Research &
development
Unclassified
Subtotal
Research Institute
University
Government
Individual
Unspecified
No assignee
The
number of
patents
Percentage
34
50
4.6%
6.8%
156
4
21.3%
0.5%
226
470
24
43
17
24
7
157
30.8%
64.0%
3.3%
5.9%
2.3%
3.3%
1.0%
21.4%
applications that were identified in the study included gas or water
purification, agricultural products such as fertilizers, soil amendments, or soil conditioners, mine filling, fillers such as those for
plastic resin, abrasives, and others, a source of metals, and mineral wools that can be used for insulation. The remaining patent
in the “miscellaneous” category included CCB uses in a magnetic
field shield, surface coatings, a metal matrix composite, ceramic or
soda-lime glass, electrophotographic imaging, artificial turf, landscape pebbles, animal litter, reinforcing materials for shoes, and
others.
In all 21 reuse categories, fly ash was the most widely used
CCB component. Fly ash has attractive characteristics for various
applications. Its fine particle size distribution, large surface area,
and spherical particle shape are ideal properties for mineral filler
in asphalt, flowable fill, and treatment absorbents. Its pozzolanic
and/or cementitious properties, depending on the type of fly ash,
make it a popular ingredient in cement, concrete, and related products, and its consistency and abundance make it easily usable
in structural fills and other highway applications (ACAA, 2003).
Fly ash contains hollow spherical particles known as cenospheres
that have excellent insulating properties and are valuable fillers in
paints, plastics, and metal alloys. The majority of patents involving
FGD gypsum were for processing technologies, with the remaining
patents related to technologies that incorporate FGD gypsum into
gypsum panel products, cement products, and agricultural products. The advantage of FGD gypsum is that its composition is similar
to mined gypsum and it is easy to obtain high purity (NETL, 2006).
FBC ash is also used in diverse applications, although the number
of technological developments regarding FBC ash remains small.
However, the development of FBC ash reuse technology is expected
to grow as fluidized-bed combustion technology becomes more
widely adopted. Boiler slag and bottom ash patents indicated their
particular uses in aggregate, mineral wool, and pavement.
Technological innovations compiled in this analysis were
driven primarily by businesses (470 patents or 64%), as shown in
Table 1. Excluding businesses that could not be classified further
into sub-categories, 21% of patents (156 patents) were assigned
to businesses using CCBs, whereas 5% (34 patents) and 7% (50
patents) of patents were assigned to businesses generating CCBs
and businesses acting as intermediaries between generators and
users of CCBs, respectively. Assuming this proportion is consistent
across the “business” category, then the actors that predominantly
drive these innovative activities are the businesses that need to use
CCBs. Representative businesses include the Wisconsin Electric
Power Company, Halliburton, the United States Gypsum Company, Lafarge Canada, N-Viro International Corp., Amax Resource
J.Y. Park / Research Policy 43 (2014) 1816–1826
30
25
20
15
10
Mixture of CCBs or Unspecified
FGD Gypsum
FBC Ash
Fly Ash
Boiler Slag
Bottom Ash
Total Patent Applications
Total Patents Grant
5
0
35
The number of CCB patents
500
450
400
350
300
250
200
150
100
50
30
25
20
15
Number of Patents
Normalized by Patent Applications
Normalized by Patents Grant
10
5
0
0.045
0.04
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
Normalized patenting (%)
The number of CCB patents
35
Total pantets (thousnads)
1820
Fig. 2. The number of CCB patents filed each year between 1950 and 2009 according to the target CCB components, total patent applications and total patents grant each
year between 1963 and 2009 (above), and the CCB-patent counts normalized by total patent applications and by total patents grant (unit: %) each year between 1963 and
2009 (below). The data for total patent statistics were obtained from the U.S. Patent and Trademark Office (1963–2012).
Recovery Systems, Inc., American Fly Ash Company, G. & W.H.
Corson, Inc., JTM Industries, Inc., and The Dow Chemical Company.
The diversity of industrial actors that participate in innovation
appears to be a key characteristic of waste reuse technology. Waste
reuse links generators, processors or marketers, and users in different sectors of industry. This presents challenges to cooperation
because these industries are not in the traditional supply chain;
however, it also presents opportunities for knowledge sharing and
positive spillover for technology development. For CCBs, the primary actors for innovation are businesses that use CCBs. For this
type of business, incentives for innovation are most likely to occur
in the input price structure. Therefore, this suggests that market
demand factors may play a certain role in the innovation of reuse
technologies.
4.2. The development of CCB reuse technology and its
relationship to drivers
Fig. 2 demonstrates the longitudinal trend in patent filings
since 1950 and Fig. 3 presents the patent filings in the context of
economic, regulatory, and institutional environment, which may
impact on innovation. Prior to the 1950s, patents related to CCB
reuse were sporadic, with only one or two per year. An overall
trend shows that the number of patents has increased rapidly since
1967, peaking in the early 1980s and 1990s, and decreasing after
2003. According to the pattern of patents normalized either by
total patent applications or total patents grant, relative patenting activities for CCB reuse technologies started to decrease from
1993 instead of 2003. This implies that patenting between 1993
and 2003 could be partly explained by the increase in propensity
to patent. Overall, this trend shows a similar temporal distribution of patents for waste recycling technologies in the United States
studied elsewhere (OECD, 2008). Based on this pattern, the period
between 1967 and 2009 can be divided into the following three
phases with distinct characteristics: Phase 1 (1967–1980), characterized by a rapid increase in the number of patent filings, Phase 2
(1981–2002), characterized by a leveling off in patent filings, and
Phase 3 (2003–2009), characterized by a decreased in the number
of patent filings.
4.2.1. Phase 1: Rapid growth (1967–1980)
For environmental regulations and environmental technologies
in general, the first large-impetus for innovation occurred during the 1970s. Major command-and-control type regulations were
established to control air and water pollution, and regulation was
the primary means to achieve environmental goals and spurred
the development of environmental technologies (National Science
and Technology Council, 1995; Office of Technology Policy, 1998).
One example is desulfurization technology. The patenting activity
associated with desulfurization technology increased coincidently
with the adoption of the 1970 Clean Air Act (CAA) and the 1971
New Source Performance Standards, which established a national
market for desulfurization technology (Rubin et al., 2004; Taylor
et al., 2003).
During this period, the number of patents related to CCB reuse
began to increase. In 1967, 6 patents were filed and the number
of patents increased to 26 in 1980. This pattern of patent filing,
particularly between 1970 and 1980, was highly correlated with
changes in the prices of cement and lime while the level of construction activities remained stable. Considering that the majority
of patents filed each year are targeted toward the reuse of fly ash, it
is understandable that the cement and lime prices showed a higher
correlation with patent filings than either the sand/gravel or gypsum price during this period. The price of construction sand and
gravel was too low and stable to significantly impact innovation.
The price of gypsum has also remained low following a continuous
decline since 1948. The impact of price on innovation may be partially explained by the fact that CCB reuse involves components of
environmental product innovation. The previous analysis of innovation patterns in this study showed that the majority of innovation
occurred to incorporate CCBs into a product, such as concrete or
gypsum panel. Additionally, the majority of inventors were businesses that used CCBs. It is likely that input price factors motivated
these actors toward innovation. The role of price factors, however,
J.Y. Park / Research Policy 43 (2014) 1816–1826
Lime Price
Construction Activities
140
ASTM
’10 C2P2 Suspended
’10 Proposed Rule
’08 TVA Spill
ASTM
’06 NAS Report
’05 CAMR
’03 C2P2
ASTM
’00 RD
’97 ASTM
’78 USWAG
’98 RMRC
’99 RTC
’93 RD
’80 SWDAA
Regulatory
’76 RCRA
’60 CAA
Timeline
(1950 ~ 2010)
Institutional
’95 ASTM
0
’89 UWM-CBU
20
0
’90 CAAA
5
’85 CARRC
40
’87 ACI226.3R
60
10
’88 RTC
80
15
’83 EPA Guide.
100
20
’82 CAER
25
’78 ASTM C618
120
’74 CRC
30
’68 NAA
The number of patents
Cement Price
Gypsum Price
Price ($98/metric ton) or
construction activities (10
million $96)
Number of Patents
Construction Sand and Gravel Price
35
1821
Fig. 3. The number of CCB patents filed each year between 1950 and 2009 and changes in the price of cement, lime, construction sand and gravel, and gypsum (unit: constant
dollars of 1998/metric ton gross weight) and in the level of construction activities (unit: value of construction put in place in 10 million of 1996 constant dollars) (above),
and selected regulatory and institutional actions during the time period (below). The red arrows below the timeline represent regulatory actions, whereas the blue and gray
arrows above the timeline represent institutional activities and the establishment of standards or relevant events, respectively. The solid arrows represent actions favorable
to CCB use, whereas the dotted arrows represent unfavorable actions or events. (For interpretation of the references to color in this figure legend, the reader is referred to
the web version of the article).
was evident only between 1970 and 1980 when the innovation for
CCB reuse technologies began to increase. Based on this observation, it is hypothesized that innovation first obtained momentum
through economic drivers.
Regulatory actions were also examined to determine their
impact on innovation in addition to economic factors. The following
two important regulations were instituted during this period: the
Clean Air Act of 1970 and the Resource Conservation and Recovery
Act of 1976. The Clean Air Act (CAA) forced utilities to collect all the
fly ash they generated to reduce its influence on air quality (Ward,
2010). This likely led to questions regarding how to make use of this
increased amount of ash. The Resource Conservation and Recovery
Act (RCRA) is the dominant statute governing the management and
use of CCBs. The original draft of the RCRA did not address whether
CCBs should be regulated as either hazardous or non-hazardous
waste. It was not until 1980 that CCBs were exempted from the
Subtitle C, hazardous waste regulations through the Solid Waste
Disposal Act Amendment, known as the Bevill Amendment (USEPA,
2010d). Through this exemption, CCBs avoided stricter regulatory
requirements and restrictions as well as a harsher public perception. Still, CCBs have remained subject to Subtitle D, non-hazardous
waste regulations.
There were several important institutional actions regarding
CCBs use during these years. In 1967, the first Ash Utilization
Symposium was held in Pittsburgh, Pennsylvania, as a result of continuous activities to address coal ash utilization. Discussions from
this symposium then led to the establishment of the National Ash
Association, a leading trade association on coal ash technology and
utilization, and a forerunner to the ACAA (Manz and PflughoeftHasset, 2005; The Coal Ash Resources Research Consortium, 2009).
ACAA started to publish CCB production and use statistics since
1977. In 1978, the Utility Solid Waste Activity Group (USWAG)
was created to address CCB-related regulatory issues (Manz and
Pflughoeft-Hasset, 2005). Currently, the ACAA and USWAG continue to actively lead CCB reuse efforts and market expansion. In
the same year, the first ASTM standard specification for the use of
CCBs was published (American Society for Testing and Materials,
1978), which was later superseded by following ASTM standards
and adopted by ACI and AASHTO standards.
4.2.2. Phase 2: Leveling off (1981–2002)
Environmental policy development continued during the 1980s
with cleanup efforts for contaminated sites and adoption of the
polluter-pays approach. Nameroff et al. (2004) observed a large
increase in the number of patents for green chemistry during
this time period with Superfund and the 1990 CAA as the major
amendments in environmental regulation. However, entering into
the 1990s, environmental policies became less important as environmental performance became acceptable compared to that of
the 1960s. Additionally, an economic recession made the environment less of a priority. The issuance of regulations slowed and the
enforcement became weaker, which led to an increase in regulatory uncertainty and stagnation in the demand for environmental
technology; therefore the competitiveness of many environmental industries decreased (National Science and Technology Council,
1995; Office of Technology Policy, 1998). Rather than strong
governmental intervention in the form of regulations, marketbased instruments have been adopted since 1996.
Innovation was active throughout the 1980s and 1990s for CCB
reuse technologies, with more than half of all patents (411 patents
or 58%) filed during this second period. Starting in this period,
the relationship between the price of natural resources and patent
filing became less evident and failed to support the role of price
with regard to the promotion of innovation.
During these two decades, a series of regulatory decisions
upheld the Bevill Amendment, which exempted CCBs from hazardous waste regulations. The EPA reaffirmed the exemption of
large-volume utility CCBs in a report to Congress in 1988 and issued
the final regulatory determination in 1993.3 In 1999 and 2000,
3
The CCBs exempted from the 1993 final regulatory determination included fly
ash, bottom ash, boiler slag, and FGD materials generated from coal-fired electric
utilities and independent power producers.
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J.Y. Park / Research Policy 43 (2014) 1816–1826
the EPA submitted a second report to Congress and published a
regulatory determination concluding that the remaining fossil fuel
combustion wastes also fell under the hazardous waste exemption
and that reusing these wastes posed no significant risks (USEPA,
2010d).4
The Clean Air Act Amendment (CAAA) of 1990 required the
control of sulfur dioxide and nitrogen emissions through an acid
deposition control program (USEPA, 2010a). This affected the quantity and quality of CCBs (Pflughoeft-Hasset et al., 1999). For CCB
quantity, the installation of desulfurization units in utilities led
to the massive production of a new type of CCBs, the FGD materials. The increasing quantities of a benign by-product such as
FGD gypsum may lead to the development of new technologies
for the utilization of these materials. However, the effect of CAAA
on patenting for FGD gypsum was not entirely evident as shown
in Fig. 2. Patents for FGD gypsum has been filed since 1972 and
the use of a desulfurization unit already occurred before the CAAA.
The reporting of the production and use of FGD materials by ACAA
began in 1986. The use of FGD gypsum would benefit from existing
knowledge regarding the use of natural gypsum and other synthetic
gypsum due to their similar compositions. From a quality aspect,
nitrogen oxide-control equipment, such as NOx burners or selective catalytic reduction, deteriorates the quality of fly ash either
by allowing a higher percentage of carbon carryovers or by leaving ammonia remain in the ash (Pflughoeft-Hasset et al., 1999).
This may adversely affect the reuse market and innovation; however, this may also lead to the development of technologies and
counteract these adverse effects to maintain the reuse markets.
On the institutional side, four research institutes were established for basic research on the utilization of CCBs: The Center for
Applied Energy Research in 1982, the Coal Ash Resources Research
Consortium in 1985, the University of Wisconsin-Milwaukee Center for By-products Utilization in 1989, and the Recycled Materials
Resource Center in 1998. Housed at universities, these institutes
often formed a consortium with government and industry to generate scientific and engineering knowledge for CCBs, develop reuse
applications, and support relevant regulations and specifications.
This period was also characterized by a burgeoning establishment
of standards. Table 2 presented 20 ASTM standards and 2 ACI standards instituted during this period. These standards cover the use
of CCBs in more diverse applications such as in structural fills, soil
stabilization, waste solidification, and mine reclamation, as well
as test methods for sulfur, mercury, carbon, and major/minor elements in CCBs. However, these are not a comprehensive list of
standards and there may be many more that address the use of
CCBs as the knowledge became more widely spread. In 1983, the
EPA implemented federal procurement guidelines that promoted
the purchase of cement and concrete products containing fly ash
(The Coal Ash Resources Research Consortium, 2009).
4.2.3. Phase 3: Decline (2003–2009)
Since 2003, patent filings have decreased and the number of
patents has remained low although there were a few institutional
movements that were favorable toward CCB reuse. In 2003, the
EPA began sponsoring the Coal Combustion Products Partnerships
(C2P2) program, a partnership formed among industries, the EPA,
the Department of Energy, and the Department of Transportation’s
Federal Highway Administration to promote the beneficial use of
CCBs (Ward, 2010). This program was suspended in 2010, however,
following a large ash spill at the Kingston plant of the Tennessee
4
This included fluidized-bed combustion (FBC) waste, co-managed waste, CCBs
from non-utilities, petroleum coke combustion waste, co-burning of coal and fuel,
and oil and natural gas combustion. The Subtitle C hazardous waste regulation could
be applied to low-volume wastes depending on the management methods.
Valley Authority (USEPA, 2010e). The EPA has been reviewing and
revising the regulatory scheme since then in response to concerns and criticisms raised over their regulatory approach (USEPA,
2010c).
In 2005, the Clean Air Mercury Rule was first issued. This rule
targeted the reduction of mercury emissions from coal-fired power
plants through a cap-and-trade program (USEPA, 2010b). A leading
technology for mercury control uses activated carbon as absorbers.
If activated carbon is commingled with fly ash, then the marketability of fly ash for certain uses is decreased. For example, carbon that
absorbed mercury interferes with the air entrainment in a concrete
product (Ward, 2010). Whereas mercury control contributes to the
improvement of air quality, without alternative solutions, it is a
threat to the CCB reuse market. However, similar to nitrogen oxide
control strategies in that how these strategies impacted the residual carbon in ash and what adjustments were needed, this threat
to the CCB reuse market could be a new opportunity for technological development. The Clean Air Mercury Rule of 2005 was vacated
by the District of Columbia in 2008, and more stringent Mercury
and Air Toxics Standards for power plants were proposed in 2011
instead. Despite uncertainty, the expectation of the new rule regulating mercury may lead to innovation in the control of mercury in
CCBs to secure CCB reuse markets. However, this has not yet been
identified in the current analysis.
The above analysis identified favorable institutional efforts for
CCB reuse and innovation throughout all three phases prior to the
Kingston ash spill in 2008. The efforts are postulated to be much
larger than what is documented here based on the number of existing institutions and programs relevant to this field. Many more
industrial associations, government agencies, research institutes,
and universities are likely to be involved in information sharing to
spread reuse ideas, induce further innovation, and direct the implementation of technologies. Therefore, institutional activities appear
to be one of the factors that foster such innovations in CCB reuse
technologies.
Yet it is unclear whether regulations directly drove the innovation for CCB reuse technologies. There was no federal regulation
that required the reuse of CCBs. Instead, regulations indirectly
affected innovation by controlling the overall management and disposal of CCBs and by changing their generation and quality. These
two types of regulations provided mixed signals in terms of innovation. For example, it is possible that waste regulation hindered
the innovation for the reuse of waste materials such as CCBs, or
that the long delay in determining the regulatory status of CCBs
hindered innovation. However, it is also possible that air quality
regulations that affected the quantity and quality of CCBs induced
innovation if businesses wanted to maintain reuse markets that had
already been developed. Or, non-hazardous waste regulations may
have provided fewer barriers than hazardous waste regulations. For
CCBs, the relationship between regulation and innovation turned
out to be ambiguous, which is different from the relationship as
seen in pollution control technology.
4.3. The development of CCB reuse technology and actual
utilization of CCBs
For the implications of technological developments, questions
remain as to how innovations in CCB reuse technologies lead to the
actual utilization of CCBs. To understand the relationship between
innovation and the actual utilization of CCBs, Fig. 4 first compares
the relative shares of patents in each CCB application category with
the relative shares of actual CCB utilization in 2008 and 2009 (ACAA,
2000–2011). The relative shares of the patents were calculated as
the number of patents in each category divided by the total number of patents in all categories. The same calculation was applied
to the relative shares of actual CCB utilization. Categories such
J.Y. Park / Research Policy 43 (2014) 1816–1826
1823
Table 2
Main U.S. regulatory actions, institutional actions, and relevant events related to CCB use.
Year
Regulatory actions
1960
1967
1968
1974
1976
The Clean Air Act (CAA) was enacted and forced utilities to collect fly ash
1977
1978
1980
First Ash Utilization Symposium
The National Ash Association (NAA)
The Coal Research Center (CRC), Southern Illinois University
Resource Conservation and Recovery Act (RCRA) was passed, no determination on
hazardousness of CCBs
The first set of proposed hazardous waste management standards in the Federal
Register (43 FR 58946) exempted CCBs as one of the six “special waste” categories
from Subtitle C regulations
Section 3001(b)(3)(A)(i–iii) of the Solid Waste Disposal Act Amendments of 1980
(“Bevill Amendment”) temporally exempted three special waste, including part of
CCBs, from hazardous waste regulation
1983
1985
1986
EPA submitted a Report to Congress (RTC) on Wastes from the Combustion of Coal by
Electric Utility Power Plants (EPA530-SW-88-002), which addressed the
management of CCBs from electric utility power plants
The University of Wisconsin-Milwaukee Center for By-Products
Utilization (UWM-CBU), ACI SP-114
1989
1990
1993
The Clean Air Act Amendment (CAAA) required the control of sulfur dioxide and
nitrogen emissions through an acid deposition control program, which affected the
quantity and quality of CCBs
EPA published the first part of its Regulatory Determination (RD) in the Federal
Register (58 FR 42466), which excluded a large-volume utility CCBs from the
definition of hazardous waste
1995
1997
1998
1999
2000
Report to Congress on remaining CCBs
Regulatory Determination concluded that the remaining CCBs do not warrant
hazardous waste regulation, but Subtitle D regulations are needed for CCB disposal. It
further determined that no federal regulations are needed for the beneficial uses of
CCBs
2001
2002
2003
2004
2005
The Clean Air Mercury Rule (CAMR) was issued to target the reduction of mercury
emissions from coal-fired power plants, which affects the quality of CCBs
National Academy of Sciences (NAS)’s report on the placement of
CCBs in coal mines
The Office of Surface Mining Reclamation and Enforcement (OSM) published an
advanced notice of proposed rule (72 FR 12025) about placement of CCBs in active
and abandoned coal mines
2008
2009
2010
2011
ASTM D5759, ASTM PS23-05
ASTM E1871-97
The Recycled Materials Resource Center (RMRC), ASTM D5239, ASTM
D5016
ASTM E1266-88(1999), ASTM D6414-99
ASTM C311, ASTM C593-95(2000), ASTM E2060, ASTM D6316, ASTM
D6357-00a, ASTM D6349-00
ASTM D6722
ASTM E2243-02, ASTM E2201
Coal Combustion Products Partnerships (C2P2) program, ASTM
E2277-03
ASTM E2278-04
2006
2007
ACAA’s first Production and Use Statement
The Utility Solid Waste Activity Group (USWAG), ASTM C618
The Center for Applied Energy Research (CAER), the University of
Kentucky
EPA’s procurement guideline for the purchase of cement and
concrete products containing fly ash
The Coal Ash Resources Research Consortium (CARRC), the
University of North Dakota
The first reporting of the production and use of flue-gas
desulfurization materials by ACAA
ACI 226.3R
1982
1987
1988
Institutional actions and relevant events
EPA proposed to regulate CCBs with two possible options
A Mercury and Air Toxics Standards for power plants were proposed
Tennessee Valley Authority’s ash spill
AASHTO Standard practice for coal combustion fly ash for
embankment
The C2P2 program was suspended
ASTM D7762, AASHTO Standard specification for coal fly ash and raw
or calcined natural pozzolans for use in concrete (same as ASTM
C618)
*ASTM C618 Standard specification for fly ash and raw or calcined natural pozzolan for use as a mineral admixture in Portland cement concrete; ACI 226.3R Use of fly ash in
concrete; ACI SP-114 Fly ash, silica fume, slag, and natural pozzolans in concrete; ASTM D5759 Standard guide for characterization of coal fly ash and clean coal combustion
fly ash for potential uses; ASTM PS23-05 Guide for the use of coal combustion fly ash in structural fills (withdrawn 1997); ASTM E1871-97 Standard guide for use of coal
combustion by-products in structural fills (withdrawn 2003); ASTM D5239 Standard practice for characterizing fly ash for use in soil stabilization; ASTM D5016 Standard
test method for sulfur in ash from coal, coke, and residues from coal combustion using high-temperature tube furnace combustion method with infrared absorption; ASTM
E1266-88(1999) Standard practice for processing mixtures of lime, fly ash, and heavy metal wastes in structural fills and other construction applications; ASTM D6414-99
Standard test method for total mercury in coal and coal combustion residues by acid extraction or wet oxidation/cold vapor atomic absorption; ASTM C311 Standard test
methods for sampling and testing fly ash or natural pozzolans for use as a mineral admixture in Portland-cement concrete; ASTM C593-95(2000) Standard specification
for fly ash and other pozzolans for use with lime; ASTM E2060 Standard guide for use of coal combustion products for solidification/stabilization of inorganic wastes;
ASTM D6316 Standard test method for determination of total, combustible and carbonate carbon in solid residues from coal and coke; ASTM D6357-00a Test methods for
determination of trace elements in coal, coke and combustion residues from coal utilization process by inductively coupled plasma atomic emission, inductively coupled
plasma mass and graphite furnace atomic absorption spectrometry; ASTM D6349-00 standard test methods for determination of major and minor elements in coal, coke,
and solid residues from combustion of coal and coke by inductively coupled plasma-atomic emission spectrometry; ASTM D6722 Standard test method for total mercury in
coal and coal combustion residues by direct combustion analysis; ASTM E2243-02 Standard guide for use of coal combustion products (CCPs) for surface mine reclamation:
re-contouring and highwall reclamation (withdrawn 2011); ASTM E2201 Standard terminology for coal combustion products (withdrawn 2011); ASTM E2277-03 Standard
guide for design and construction of coal ash structural fills (withdrawn 2012); ASTM E2278-04 Standard guide for use of coal combustion products (CCPs) for surface mine
reclamation: revegetation and mitigation of acid mine drainage (withdrawn 2013); ASTM D7762 Standard practice for design of stabilization of soil and soil-like materials
with self-cementing fly ash.
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40%
Million metric tons
Relative Shares of CCB Use in 2008
35%
0
2
4
6
8
10
12
14
16
Relative Shares of CCB Use in 2009
30%
Relative Shares of Patents
Concrete Products
25%
Cement/Raw Feed for Clinker
20%
15%
Flowable Fill
10%
Structural Fills/Embankments
5%
2001
2002
2003
0%
Road Base/Sub-base/Pavement
2004
Fig. 4. Comparison between the shares of patents in each category to all patents
filed between 1875 and 2010 (scattered plot) and the shares of CCB use in each
category to the overall amount of CCBs used during 2008 (dark bars) and 2009 (light
bars) as reported by ACAA.
Soil Modification/Stabilization
2005
Mineral Filler in Asphalt
2006
2007
Snow and Ice Control
2008
Blasting Grit/Roofing Granules
2009
Mining Applications
as road base/sub-base, cement products, concrete products, and
waste stabilization show comparable levels of both relative patent
shares and CCB utilization. For gypsum panel products and mining applications, however, the amount of utilization far outweighs
the respective proportion of patents. This indicates that technologies that were developed for these applications utilized a relatively
large amount of CCBs during both years. By contrast, categories such
as aggregate and agricultural use show the reverse gap between the
level of technological development and the level of CCB utilization.
This indicates that technological development as measured by the
number of patents does not always correlate with a greater amount
of CCB utilization. Although it is important to develop more technologies, it is equally or more important to develop technologies
that can use a larger amount of CCBs. For example, there was only
one patent identified for snow and ice control, but the actual utilization of CCBs in this category was greater than 1% of the total
CCB utilization in 2009 (ACAA, 2000–2011).
Fig. 5 shows an overlap of the temporal pattern of patent filings with the amount of CCBs used and the reuse rate since 1966,
the earliest year for which data were available. Overall, greater
technological innovation appeared to result in the higher utilization of CCBs. This shows a correlation between innovation and the
evolution of CCBs from waste into resources. The period between
1966 and 2009 can be divided into three phases according to the
relative growth patterns of patent filings and CCB reuse. The rate
of growth for patent filings was similar to that of CCB use during the first phase between 1966 and 1978, but began to exceed
Cumulative No. of Patents
Cumulative number of patents
700
600
500
400
300
CCB Used (million metric tons)
CCB Reuse Rate (%)
50
40
30
20
200
100
0
10
The amount of CCBs used (million metric
tons) or Reuse rate (%)
60
800
0
Fig. 5. Cumulative number of patents filed (bar graph, reading on the left axis), the
total amount of CCBs used in million metric tons (solid line graph, reading on the
right axis), and the reuse rate of CCBs in percentage (dotted line graph, reading on
the right axis) each year between 1966 and 2009. The data for the line graph were
obtained from Kelly and Sullivan (2006).
Gypsum Panel Products
Waste Stabilization/Solidification
Agriculture
Aggregate
Miscellaneous
Fig. 6. The amount of CCBs used in each category from 2001 to 2009.
that of CCB use during the second phase between 1978 and 2000.
The same relationship holds even when the amount of CCB used
is normalized by their total generation (i.e., reuse rate). This indicates that not all technological developments necessarily resulted
in actual CCB use, suggesting the existence of barriers to the adoption and diffusion of CCB reuse technologies as well as barriers to
the reuse of CCBs. Although the possibility of CCB reuse increased as
more technologies were developed, actual reuse did not increase
as much as expected due to various economic, technical, and/or
informational barriers. During the third phase, from 2001 to 2009,
CCB use or reuse rate increased faster than the rate of patent filings. This increase in CCB use during the third phase is likely a
result of the wider implementation of certain CCB reuse technologies that were previously developed rather than the result of new
innovation.
To determine which technological implementation primarily
drove the actual increase in CCB use during the third phase, the
amount of CCBs used in each reuse category between 2001 and 2009
was analyzed (Fig. 6) (ACAA, 2000–2011). CCB use in constructionrelated activities such as concrete products, cement, structural
fills/embankments, and gypsum panel products, increased the total
amount of CCBs used from 2001 to 2006. Since 2007, mining applications have been the primary category contributing to the increase
in CCB use. The sudden increase of CCB reuse in mining applications was partly due to a change in data. Beginning in 2007, ACAA
statistics have included FBC ash data from ARIPPA, a trade association located in Pennsylvania comprising co-generation plants
using alternative fuels, such as coal refuse or biomass, and businesses associated with that industry (ARIPPA, 2011). The continued
increase of CCB use in mining applications after 2007 reflected
the burgeoning application of mine backfilling technology using
CCBs.
J.Y. Park / Research Policy 43 (2014) 1816–1826
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5. Policy implications
6. Conclusions
Analysis of the innovation pattern showed that innovation for
CCB reuse technologies involved diverse industrial actors, because
waste reuse could only happen with the cooperation of generators,
processors, marketers, and users in different sectors of industry.
This presents challenges regarding how to incentivize innovation
for a waste reuse technology because different industrial actors
are likely to have different incentives for innovation. For example,
waste generators are more likely to respond to disposal regulations,
whereas waste users are more likely to be influenced by input price
factors. To some extent, the examination of potential drivers of
innovation for CCB reuse technology in the second part of this study
corroborated this expectation by showing the mixed influence of
market, institutional, and regulatory factors.
For CCBs, the number of patents for reuse technologies and the
normalized patenting activities began to increase in response to the
changes in the price of cement and lime, which can be substituted
by fly ash. If this is applicable to other waste reuse technologies,
it suggests that the high price of natural counterparts can initiate
the evolution of a waste material into a potential resource, and
conversely, an insignificant price gap between natural and waste
materials cannot initiate this evolution. Therefore, a government
subsidy granted toward natural resources can hamper the use of
waste substitutes and innovation for waste reuse technologies. This
role of market dynamics on innovation, however, needs to be corroborated through further studies.
Although favorable market dynamics provide the initial drive for
innovation, innovation also requires institutional support to maintain momentum. After the 1980s, when the role of price factors
became less evident, the large number of patent filing could be
explained by active institutional support, such as the establishment
of standards that approve the use of CCBs, industrial associations, government procurement programs, and research institutes
dedicated to the promotion of CCB reuse through research and
development, training, and outreach. The mobilization of institutional resources, however, requires concerted efforts. CCBs have
favorable characteristics that garner institutional support, such
as enormous quantity and potential toxicity that attract national
attention, and/or the involvement of utility power sectors. But
waste with a smaller quantity, for example, may find it hard to
obtain the same level of institutional support.
The role of regulatory actions as drivers of innovation could not
be determined in this study, but this study implicitly demonstrated
the problem of current regulatory systems. It has taken more than
30 years for federal regulations to be finalized regarding the management of CCBs, and this process still remains ongoing, which
increases the uncertainty surrounding CCB reuse. Regulations have
also put a stronger focus on controlling CCB disposal rather than
supporting their reuse. Even though it is unrealistic to expect that
all regulations, particularly regulations that have an indirect impact
on the quantity and quality of waste materials, should be designed
to support waste reuse, there should at least be regulations that
provide a channel for the safe reuse of waste.
In addition to these drivers of innovation, realizing the
latent value of waste requires efforts to remove barriers to the
implementation of reuse technologies in the market. This study
demonstrated the existence of a lag between innovation, as measured in terms of patent filings, and the actual use of CCBs. This
is partly because of various economic, regulatory, and behavioral
barriers in the reuse market and the varying values of individual
patents. To increase the actual use of CCBs, it is important to address
these barriers and to focus both on the nature of innovation and the
level of innovation. The development of technologies that reuse a
greater amount of CCBs can be equally or even more important than
the development of a greater number of technologies.
This study examined the innovation patterns and processes of
a specific waste reuse technology using patent data. Based on a
total of 707 patents identified since 1875, the study demonstrated
that the majority of innovation occurred to incorporate CCBs into
concrete and cement products, and also by businesses, particularly
businesses that require CCBs. These observed patterns of innovation suggest a certain role of market factors in driving innovation.
Environmental product innovation is known to be governed primarily by market factors, and users of CCBs are more likely to be
motivated to innovate by input price factors.
To understand the cause and effect of innovation, temporal patterns of patent filing were examined in relation to potential driving
factors and the actual use of CCBs. Between 1970 and 1980, a strong
correlation was observed between the patent filings and cement
and lime prices, indicating the possible influence of substitute
prices on innovation. During the 1980s and 1990s, however, the
role of price factors became less evident. A large number of patents
filed during this period could instead be explained by institutional
support, such as the establishment of standards that approve the
use of CCBs, industrial associations, government procurement programs, and research institutes dedicated to the promotion of CCB
reuse through research and development, training, and outreach.
Regulatory actions at the federal level were also examined, but their
role as drivers of innovation was indeterminable. Overall, innovation measured in terms of patent filing overlapped well with the
increasing pattern of actual CCB use since 1966, suggesting a positive impact of innovation on actual use. However, the actual amount
of CCBs that were reused increased with a lag following the increase
in the number of patent filings. These lags were most likely due
to varying values of individual patents and barriers to technology
implementation in the reuse market.
Based on these results, this study identified unique characteristics of innovation for a waste reuse technology. In the case of
CCB reuse technologies, the impact of regulation on innovation
was uncertain, which is different from the previous findings that
observed a strong role of regulation in inducing innovation, particularly in the case of pollution control technologies. There was no
federal-level regulation that required the reuse of CCBs, but there
were regulations that directed their disposal and influenced the
quantity and quality of CCBs. These regulations had indirect impacts
on innovations and sometimes exerted mixed signals. Another
characteristic of innovation for a waste reuse technology was that
it involve diverse industrial actors. This has an important policy
implication regarding how to incentivize different industrial actors
with varying motivations.
The analyses conducted in this study provide an initial understanding about the development of CCB reuse technologies, but
with limitations. It ignored innovations were not patented and did
not consider varying values and the content of innovation. Also, this
study did not address any knowledge transfer or spillover effects
between countries and different technology areas, which may have
a sizable impact on the innovation of CCB reuse technologies. In
exploring potential drivers of innovation, this study examined a
limited set of factors and in a qualitative fashion. More studies need
to be done to address these aspects and to provide additional empirical findings to broaden our understanding of innovation for various
waste reuse technologies.
Acknowledgements
The author gratefully acknowledges a scholarship from the
Environmental Research and Education Foundation, which supported this research during the author’s Ph.D. program. The author
would like to thank Prof. Marian Chertow, Prof. Thomas Graedel,
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Prof. Matthew Kotchen, and Reid Lifset for their assistance and
feedback.
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