TOPICAL REPORT NUMBER 24 AUGUST 2006

Coal Utilization

By-Products
Cover Photos:

Top: Building materials used in the

Lewis & Clark Visitors Center in

Fort Mandan, ND include fly ash-based

mortar and stucco, wall board, and

high-volume fly ash concrete.

Bottom left: The Ronald Reagan

Building and International Trade Center

in Washington, D.C. was built with

concrete containing fly ash.

Bottom right: Fly ash is an important

component in mass concrete projects,

such as the Glen Canyon Dam near

Page, AZ.

Acknowledgement:

DOE greatly appreciates the

participation of the American Coal

Ash Association in the preparation of

this Topical Report.
Coal Utilization By-Products

Executive Summary .............................................................................................. 5

Introduction .......................................................................................................... 6

Where Do CUBs Come From? ............................................................................. 8

CUB Properties and Uses ................................................................................... 10

Market Analysis .................................................................................................. 14

DOE-Sponsored CUB Demonstrations .............................................................. 17

Examples of Best-Practice Utilization of CUB Materials .................................. 18

Factors Limiting the Use of CUBs ..................................................................... 22

Conclusions ........................................................................................................ 25

Acronyms and Abbreviations ............................................................................. 26

Bibliography ....................................................................................................... 27

5

Executive Summary

The Clean Coal Technology Demonstration

Program (CCTDP) is a government and

industry cofunded effort to demonstrate a new

generation of innovative coal utilization

processes in a series of facilities built across

the country. These projects are carried out on a

commercial scale to prove technical feasibility

and provide information for future applications.

The goal of the CCTDP is to furnish the

marketplace with advanced, more efficient

coal-based technologies that meet strict

environmental standards. Use of these

technologies is intended to minimize the

economic and environmental barriers that

limit the full utilization of coal.

To achieve this goal, beginning in 1985,

a multiphase effort consisting of five separate

solicitations was administered by the U.S.

Department of Energy (DOE) through its

National Energy Technology Laboratory.

Selected projects have demonstrated

technology options with the potential to meet

the needs of energy markets while satisfying

relevant environmental requirements. Two

follow-on programs have been developed

that build on the successes of the CCTDP:

the Power Plant Improvement Initiative

(PPII) and the Clean Coal Power Initiative

(CCPI).

Under the latter programs, three projects

have been selected or are underway with the

goal of increasing the use of coal utilization

by-products (CUBs) in construction and

other industries. One of these projects falls

under PPII and is being conducted by

Universal Aggregates, LLC. The others fall

under CCPI and are being conducted by

Western Greenbrier Co-Generation and the

University of Kentucky.

CUBs are the solid materials formed

during the combustion or gasification of coal

during electric power generation. The

primary large-volume CUBs are fly ash,

bottom ash, slag, ash produced via fluidized

bed combustion, and flue gas desulfurization

by-products. Historically, CUBs have been

disposed of in ashponds, landfills, and other

sites. However, there are many incentives for

developing more beneficial uses for these

materials, including power generation

economics, the conservation of natural

resources and landfill space, and reductions

in carbon dioxide emissions.

As time passes, more and more CUBs are

being sold or reused—over 40 percent in 2004

compared to less than 25 percent in 1996

while at the same time production of CUBs

has increased significantly. Government

agencies and other stakeholders have

established a goal of 50 percent utilization by

2010.

CUBs are used in the manufacture of pre-cast concrete pipe.
Coal Utilization By-Products

Topical Report Number 24

sulfur oxides to be removed from power plant

flue gas as well. Both actions result in

increased generation of solid material

referred to as coal utilization by-products

(CUBs).

Although these materials have been

referred to as coal combustion products

(CCPs), residues, or wastes, the U.S.

Department of Energy (DOE) prefers the

term “utilization” over “combustion”

because it accounts for coal gasification,

which also produces solid by-products that

must be managed. Similarly, DOE prefers the

term “by-products” because it describes most

accurately the nature of the materials at the

moment they are generated. They become

“products” when they are sold or beneficially

utilized and “wastes” when they are sent to

a permanent disposal site.

In 1980, CUBs were designated nonhazardous wastes by the Bevill Amendment

to the Resource Conservation and Recovery

Act. Further investigation has found that their

properties often allow their beneficial use.

In some cases, these properties make the

CUB better suited for certain applications

than the naturally occurring materials they

replace.

CUB utilization improves the economics

of power generation, conserves natural

resources, avoids the consumption of

increasingly scarce landfill space, and

reduces emissions of carbon dioxide (CO2)

that would otherwise be required to produce

Introduction

Coal contains a substantial number of

impurities, including mineral matter and

sulfur. When coal is burned, the mineral

matter is converted to ash and the sulfur is

converted to sulfur oxides.

Coal-fired power plants have long been

required to remove the bulk of the ash

entrained in the flue gas. Now, environmental

regulations are requiring more and more

CUB samples, clockwise from upper left: fly ash, bottom ash, FGD material, and boiler slag.

6
the raw materials for which CUBs are

substituted. CUBs are increasingly being

sold or reused—more than 40 percent in

2004 compared to less than 25 percent in

1996. Government agencies and other

stakeholders have established a goal of 50

percent utilization by 2010.

The principal organization promoting the

beneficial use of CUBs is the American Coal

Ash Association (ACAA). In addition, the

U.S. Department of Energy’s Power Plant

Improvement Initiative (PPII) and Clean

Coal Power Initiative (CCPI) sponsor a

number of projects that promote the

utilization of diverse types of domestic

CUBs. Several of these projects are noted

throughout this report.

7

Magnified view of boiler slag
 Chemical Composition of Representative Fly Ashes, weight % 

Class F Fly Ash Class C Fly Ash Portland Cement 

Compound 

Typical* 

ASTM 

C-618 Typical* 

ASTM 

C-618 Typical** 

ASTM 

C-150 

SiO2 53.6 --- 40.9 --- 20.3 --- 

Al2O3 26.3 --- 21.6 --- 4.3 --- 

Fe2O3 5.2 --- 5.5 --- 2.6 --- 

SiO2+Al2O3

+Fe2O3

90.7 70.0 

(min) 

67.7 50.0 

(min) --- --- 

CaO (Lime) 4.1 --- 19.1 --- 63.6 --- 

MgO 1.5 --- 3.9 --- 2.2 

6.0 

(max) 

Sulfate as 

SO3 0.9 

5.0 

(max) 1.4 

5.0 

(max) --- 

3.0 

(max) 

Loss on 

Ignition 6.0 6.0 6.0 6.0 0.6 

3.0 

(max) 

Moisture 

Content 

0.2 3.0 

(max) 0.0 

3.0 

(max) --- --- 

Insoluble 

Residue 0.0 --- 0.0 --- --- 

0.75 

(max) 

Available 

alkalies as 

Equivalent 

Na2

O 2.0 --- 1.6 --- 0.2 --- 

*Class F ash from We Energies Presque Isle Plant, Class C ash from We Energies Pleasant Prairie Plant – 

both normalized and adjusted to 6% LOI for ease of comparison with ASTM C-618 

**Type 1 Portland cement – Lafarge Corporation 

Where Do CUBs Come

From?

The combustion of coal to generate

electric power results in the formation of a

variety of solid materials, collectively

referred to as CUBs. The principal CUBs are

fly ash, bottom ash, boiler slag, ash produced

via fluidized bed combustion (FBC), and byproducts of flue gas desulfurization (FGD).

Pulverized coal and cyclone boilers

normally produce fly ash, bottom ash, and

slag. A substantial quantity of fly ash is

entrained in the boiler flue gas and collected

8

in electrostatic precipitators (ESPs) or

baghouses. Bottom ash is formed when ash

particles soften or melt and adhere to the

furnace walls and boiler tubes, agglomerating

and falling to hoppers located at the base of

the furnace. Some bottom ash is transported

to storage dry, but most is transported as a

slurry to dewatering bins or ponds, where

water is removed prior to the ash’s transfer to

utilization sites or storage stockpiles.

The yield ratio of fly ash to bottom ash

depends on boiler type. In dry-bottom

boilers, fly ash constitutes the major ash

component at 80–90 percent, with bottom

ash in the range of 10–20 percent.

Wet-bottom boilers yield molten ash, or

slag, from the furnace bottom. Slag removed

from the boiler in a molten state is dropped

into a water-filled ash hopper. When it is

quenched, it shatters and forms boiler slag

particles.

In cyclone boilers, the slag yield is a

greater percentage of total ash (70–85

percent). The ratio of slag to fly ash in other

wet-bottom boilers is about the same as that

of bottom ash to fly ash in dry-bottom units

(10–20 percent slag and 80–90 percent fly

ash).
FGD material is produced when sulfur

dioxide (SO2) is removed from stack gases.

This occurs in the flue gas scrubbers when

slurried limestone or lime reacts with the

gaseous SO2 to produce calcium sulfite

(CaSO3).

In “wet” FGD systems, which are by far

the most common in large, coal-fired utility

boilers, SO2 removal takes place downstream

of the particulate removal device. In many

installations, CaSO3 is further oxidized to

calcium sulfate (CaSO4). Because the sulfate

material is in an aqueous slurry, it forms the

hydrate, CaSO4 · 2H2O (gypsum).

9

Flowable fill typically contains fly ash and water and may contain small amounts of Portland cement.

“Dry” FGD systems are installed

upstream of the particulate removal device,

which removes the sorbent reaction products

(CaSO3 or CaSO4) along with the fly ash and

the unreacted sorbent, lime.

When combustion takes place in an FBC,

limestone is fed into the boiler with the coal

for SO2 removal. Bottom ash, fly ash, and

sorbent (a small portion of which is

unreacted) are removed. A dry FGD system

may be added between the FBC and

particulate removal device if greater SO2

removal is required.
CUB Properties

and Uses

Fly Ash

Fly ash is a fine, powdery material and by

far the largest-volume CUB. Its particles are

spherical in shape, glassy, with a size similar

to that of silt. The chemical make-up of fly

ash depends primarily on the chemical

properties of the coal burned, but also on the

grinding equipment, furnace, combustion

process, and nitrogen oxide (NO

X)-control

equipment used. The properties of a particular

fly ash are the key factor in determining its

potential use in manufacturing and

construction applications.

ASTM International (formerly the

American Society for Testing and Materials)

classifies fly ash into two categories—Class F

and Class C. Combustion of bituminous and

anthracite coals (except in FBCs) usually

produces Class F, a pozzolanic ash containing

silicon, aluminum, and high levels of iron.

Pozzolanic materials, a term originally applied

to volcanic ash, form cement when mixed with

water. The combustion of subbituminous and

lignite coals usually produces Class C, a

pozzolanic and cementitious ash high in

calcium or lime.

The most common and economical use for

Class C fly ash is as a partial replacement for

Portland cement in concrete manufacturing

(normally up to 30 percent, but can be as high

as 50 percent in some applications). In 2004,

approximately 14 million tons were used in

this capacity, generating several hundred

million dollars in revenue and demonstrating

the wide acceptance fly ash enjoys in the

concrete industry.

Two significant benefits are realized when

fly ash is used to displace Portland cement.

First, aluminosilicates in the ash react with

calcium hydroxide, augmenting its

cementitious properties and increasing the

strength and durability of the final product.

Second, Portland cement production releases

high levels of CO

2. For every ton of fly ash

used in replacement, one ton of CO

2 emission

is avoided. This could prove to be a significant

element of an overall U.S. greenhouse gas

reduction strategy.

In addition to cement manufacture, fly

ash is used to produce controlled lowstrength material, also known as flowable fill,

and as a filler in plastic compounds. Flowable

fill pours freely, sets up quickly, and has the

strength of compacted soil. In construction,

it cuts man-hours and improves worker safety

by allowing trenches to be backfilled

remotely rather than manually. In mining, it

is used as backfill and is especially useful in

preventing underground mine subsidence.

The finest-sized fly ash is used as filler in

plastic compounds, increasing the stiffness

of the plastic and reducing production cost

by displacing plastic resin.

The applications noted above use fly ash

with low carbon content, formally the

predominant fly ash produced by U.S. coalfired power plants. Due to changes in

environmental controls, however, high-carbon

fly ash is becoming more common. Efforts

are underway to identify uses for such

material, and two have been closely

investigated.

The first is fuel. Carbon from the ash is

high in surface area, which compensates for

its low volatile matter content. Tests

conducted by the University of Kentucky’s

Center for Applied Energy Research found

a 99 percent burnout rate for the carbon

when the fly ash is reblended with the coal

feed. The second is as a sorbent material.

The carbon’s pore structure and high surface

area help it adsorb odorous gases and

organic pollutants. Applications could

include removal of organic dyes and oils

from waste streams.

In reconstructing and/or upgrading

existing pavements, Class C fly ash is used

during cold in-place recycling (also known

as full-depth reclamation). The existing

pavement is pulverized along with its base,

and the mixture is stabilized by adding fly

ash and water. A new asphaltic concrete

surface is then installed above the stabilized

section. The properties of the Class C ash

enhance the recycled pavement’s structural

capacity to a much greater extent than either

Class F ash or traditional crushed stone

aggregate could do.

10
Class C fly ash is also widely used for soil

stabilization. When properly proportioned,

disked, and compacted, the ash increases the

shear strength of soils in embankment

sections. It can also serve as a drying agent.

Soil with high moisture content can be difficult

to compact during spring and fall. Adding fly

ash to the soil quickly reduces the soil’s

moisture content to levels suitable for

compaction. Finally, Class C ash is used to

reduce the shrink-swell potential of clay soils.

The cementitious products formed by

hydrating the ash bond with the clay particles

reduce the clay’s swell potential to levels

achievable with lime treatment.

Bottom Ash

Compared to fly ash, bottom ash is much

coarser, often containing significant voids

from gas bubbles. The chemical composition

of bottom ash is somewhat similar to that of

fly ash, but it typically contains more carbon

and less volatile impurities (mercury, boron,

etc.), which tend to report to the fly ash.

Bottom ash is also more inert. Because

its particles have fused in the boiler, they

show less pozzolanic activity and are

unsuitable as an additive constituent in

cement. Bottom ash can, however, be used

as a coarse aggregate for cement blocks, with

its porous nature often qualifying the

product for lightweight classification. At

one time this was a common use. However,

quality and supply problems have reduced

the amount of ash used in this type of

product.

Today, bottom ash is most commonly

used in structural fills, road base and subbase pavement, and for snow and ice

removal.

Boiler Slag

Boiler slags normally have a particle size

in the range of 0.5–5.0 mm. Typically, its

particles are smooth in texture, but if gases

are trapped in the molten slag as it is tapped

from the furnace, the slag can be somewhat

porous. The maximum dry bulk density

values of boiler slag are 10–25 percent

lower than natural granular materials.

By far the most common use of boiler

slag is for roofing granules and blasting

grit. These applications account for over

88 percent of slag sold.

Boiler slag is also used in road

construction. It enhances hot-mix asphalt

because of its hard, durable particles and

resistance to surface wear. It finds use in

asphalt wearing surface mixtures because

of its affinity for asphalt and its dust-free

surface, which increases the asphalt’s

adhesion and anti-stripping characteristics.

And, it has been used successfully as a

seal-coat aggregate for bituminous surface

treatments to enhance skid resistance.

Because it has a uniform particle size, the

slag is usually mixed with aggregates of

other sizes to achieve target gradation.

FBC Ash

FBC ash is a relatively new CUB that

already enjoys a utilization rate of over

50 percent. It is a mixture of unreacted lime,

CaSO3, anhydrous CaSO4, and ash that is

highly alkaline in nature. It is also selfcementing, although it has a tendency to

swell.

FBC fly ash is used in structural fills

where swelling is not an issue, soil

modification, and mining applications.

Efforts are also underway to find a use for

this material in cement manufacturing.

11

 Chemical Composition of Typical Bottom Ash, weight % 

Compound Bituminous Coal Sub-bituminous Coal 

SiO2 61.0 46.8 

Al2O3 25.4 18.8 

Fe2O3 6.6 5.9 

CaO 1.5 17.8 

MgO 1.0 4.0 

Na2O 0.9 1.3 

K2O 0.2 0.3 
FGD Material

Wet FGD scrubber material is initially

formed and primarily generated as CaSO3.

Calcium sulfite sludge can be fixated with

lime, fly ash, or cement and used for road

base. However, many wet scrubber systems

include a forced oxidation step that converts

CaSO3 to CaSO4. Because this process is

carried out in the aqueous phase, gypsum

is produced.

The purity of synthetic gypsum ranges

from 96 to 99 percent, depending on the

sorbent used for desulfurization and the

amount of fly ash collected in the scrubbers

along with the gypsum. The quantity

produced is directly proportional to the sulfur

content of the fuel being burned and the

system’s SO2 removal efficiency Synthetic

gypsum is widely used for wallboard—

where its purity often makes it more desirable

than natural rock gypsum—as a road base,

and in cement manufacturing.

When used as a road base, the gypsum is

stabilized with quicklime and pozzolanic fly

ash. In cement manufacturing, it is mixed

with the “clinker” product (calcium silicates)

from the cement kiln. The gypsum acts to

control the setting time of the resulting

cement. When introduced in wet form, it also

benefits the cement grinding process by

introducing moisture into the ball mill, thus

providing additional cooling.

Several uses for synthetic gypsum

currently constitute small markets. These

include agriculture and the manufacture of

various products. However, gypsum

production is expected to rise significantly

over the next 10 years along with the increase

in scrubber installations in response to

environmental regulations. These small

markets may prove increasingly important

to synthetic gypsum utilization.

12

 Chemical Composition of Typical Boiler Slag, weight % 

Compound Bituminous Coal Sub-bituminous Coal 

SiO2 48.9 40.5 

Al2O3 21.9 13.8 

Fe2O3 14.3 14.2 

CaO 1.4 22.4 

MgO 5.2 5.6 

Na2O 0.7 1.7 

K2O 0.1 1.1 

The purity of synthetic gypsum makes it more desirable than naturally occurring rock for the

production of wallboard and other construction materials.
Agriculture

Gypsum has proven to be an effective soil

amendment in many agricultural applications

to improve drainage and provide sulfur and

calcium nutriment. However, regulators are

reluctant to allow the use of soil amendments

that contain mercury, no matter how stable.

In addition, the agriculture industry has yet

to determine which crops would adequately

benefit from gypsum application.

Ohio State University is a national leader

in testing and research in FGD gypsum

utilization in this area. The Electric Power

Research Institute (EPRI) also is conducting

data reviews and field tests of crop

productivity to demonstrate the benefit and

environmental acceptability of using gypsum

in agriculture. Depending on the outcome of

these efforts, EPRI is scheduled to conduct

groundwater and subsurface migration tests

for mercury. In addition, EPRI will conduct

agronomic analyses to determine the

economic value of FGD gypsum use with

different crops, soils, and transportation

scenarios (from power plant to farm). EPRI’s

work is being cofunded by DOE.

13

CUBs improve the chemical and physical properties of soils, promoting plant growth and

increasing productivity.

Typical Chemical Composition

of Synthetic Gypsum

Constituent Weight Fraction (%)

Ca 24.0

SO4 54.0

CO3 3.0

SiO2 2.7

Inert 1.3

H2O 15.0

pH=7

Other Applications

Gypsum can be heated to produce several

hemihydrate and anhydrite forms of CaSO4.

The specific form of CaSO4 produced is

determined by the temperature to which it is

heated, the length of time it remains at

process temperature, and whether or not the

material is agitated.

Higher-value uses for hemihydrates

include plaster of Paris and a high-strength

plaster sometimes referred to as gypsum

cement. Gypsum cement can replace

standard cement in some applications and

has found broad application in self-leveling

flooring, especially in Europe.

Anhydrites can be manufactured as

either particulates or fibers. They are used

in plastics and thermoplastics, paper,

pharmaceuticals, food, adhesives, and paint.

In plastics and thermoplastics, fibrous

anhydrites add strength to the product.
Market Analysis

In 2004, the United States produced over

122 million tons of CUBs, over 49 million

tons of which were used constructively. This

makes 2004 the first year in which over

40 percent of the CUBs from coal-fired

power plants were effectively utilized.

The market value of various CUBs is

determined by several factors. These include

the uses for which the properties of the

material make it suitable, distance to the user,

and the state and local specifications that

determine which purposes are allowed.

The ACAA estimates ranges of expected

values for some of these products:

• Cement-quality fly ash—$40–60/ton

• Self-cementing fly ash for soil

stabilization—$10–20/ton

• Bottom ash and fly ash for snow and ice

control—$3–6/ton

• Bottom ash and fly ash for road base—

$4–8/ton

• Self-cementing fly ash for oilfield grouting

and waste stabilization—$15–25/ton

• Fly ash for use in flowable fill—$1/ton

Selling price is only one economic

aspect of CUB utilization, however. If CUBs

are not used beneficially, power plants incur

costs associated with disposal, which can

be as low as $3/ton for onsite disposal but

as high as $50/ton for landfilling in areas

where space is scarce or long hauls are

required.

14

CUB Regulatory History

In the Solid Waste Disposal Act Amendments of 1980, which amended the 1976

Resource Conservation and Recovery Act (RCRA), Congress temporarily

exempted from regulation as hazardous wastes a range of CUBs (fly ash, bottom

ash, slag, and FGD wastes) under RCRA Subtitle C. Congress then directed EPA

to study the adverse effects on human health and the environment caused by

CUB disposal. The study was to be followed by a Report to Congress (RTC) and,

six months later, a regulatory determination (RD) stating whether CUBs do or

do not warrant permanent regulation.

In response, EPA took the following actions:

• 1988: Submitted the RTC, “Wastes from the Combustion of Coal by Electric

Utility Power Plants,” in which it tentatively determined that CUBs do not

warrant regulation under Subtitle C.

• 1992: In response to a suit filed by a citizens’ group because it did not publish

its RD in the required timeframe, entered into a consent decree that divided

CUBs into two categories: (1) those generated by electric utility and independent

power production facilities and (2) all remaining wastes subject to RCRA Sections

3001(b) and 8002(n). The decree contained separate schedules for providing

RDs for each category.

• 1993: Issued an RD determining that Category 1 materials do not warrant

regulation when managed alone (i.e., not co-managed with low-volume wastes).

• 1999: Issued an RTC tentatively determining that Category 2 materials should

also remain exempt from Subtitle C.

• 2000: Issued an RD determining that Category 2 materials do not warrant

regulation. However, EPA also determined that “national regulations under

subtitle D of RCRA are warranted for [CUBs] when they are disposed in landfills

or surface impoundments, and that regulations under subtitle D of RCRA (and/

or possibly modifications to existing regulations established under authority of

the Surface Mining Control and Reclamation Act [SMCRA]) are warranted when

these wastes are used to fill surface or underground mines.” The EPA also

stated that it did not want to erect unnecessary barriers to the use of these

materials because they conserve natural resources and landfill space.

To ensure the consistent regulation of CUBs across all waste management

scenarios, EPA plans to develop national regulations for CUB disposal in surface

impoundments, landfills, and as minefilling. EPA’s regulations will be applicable to

CUBs that are generated at electric utility and independent power production

facilities and not co-managed with low-volume wastes.
Fly Ash

Fly ash is the largest-volume CUB with

respect to both production and utilization

(70.8 and 28.1 million tons in 2004,

respectively). It currently finds markets in

concrete manufacturing and in road and other

construction applications. However, with a

70 percent disposal rate, it is far from being

fully utilized.

Of the 70.8 million tons of fly ash available

annually, approximately 16.5 million tons are

used as a replacement for Portland cement in

concrete manufacturing and as a component

of the kiln feed to produce clinker. In 2004,

the United States used approximately

121 million tons of Portland cement, of which

fly ash with acceptable properties could have

replaced at least 30 percent (36.1 million tons).

Therefore, substantial opportunity still exists

for fly ash in this market—though not nearly

enough to fully utilize annual production.

High-volume construction is another,

potentially large market for fly ash and one

favored by EPA. The ash can be used in road

construction, as structural and mine fill, and

for waste stabilization.

In a PPII demonstration project, Universal

Aggregates is using spray dryer absorber ash,

a mixture of fly ash and spent sorbent, to

manufacture aggregate. According to the

United States Geological Survey (USGS), the

United States uses more than 1.2 billion tons/

year of crushed stone, sand, and gravel as

aggregate. Barriers to tapping this market with

fly ash include non-acceptance in some states

of fly ash as a base material, widely varying

specifications for use where it is accepted, and

potential cost. USGS reports that sand and

gravel sold for an average price of $5.28/ton

in 2004 (f.o.b. quarry) while crushed stone

sold for $6.08/ton. The cost of manufactured

aggregate must be competitive and it must

continue to gain acceptance as a safe, reliable

material. If these conditions are met, the

potential market for manufactured aggregate

is expected to be quite large.

15

Bottom Ash

Just under 50 percent of annual bottom

ash production currently finds a market as

structural fill, road base material, and a snow

and ice control product. As acceptance for

these applications increases, these large

markets have the potential to absorb all of

the bottom ash produced annually.

The most common uses of boiler slag are roofing granules and blasting grit. However,

quantities available are decreasing as cyclone boilers are being retired.

Boiler Slag

Nearly 90 percent of the boiler slag

currently generated each year is sold on the

market, primarily as blasting grit and roofing

granules. However, much of the slag is

produced in cyclone boilers, which have

fallen out of favor due to their high NOX

emissions.
As the older cyclone boilers are retired,

the quantities of boiler slag available will

decrease. According to ACAA data,

2.57 million tons were produced in 1996

compared to 1.97 million in 2004. The boiler

slag that is produced will certainly find a

ready market.

FBC Ash

The quantities of available FBC ash are

currently small compared to other forms of

ash. However, it already enjoys a utilization

rate of over 50 percent. Its highly alkaline

nature makes FBC ash especially useful in soil

modification and to mitigate acid mine

drainage. Work is also underway to find a use

for this material in cement manufacturing.

While FBC technology has been available

for some time, recent trends indicate that

installations will increase dramatically in the

coming decade. Therefore, the use of FBC

ash also needs to grow. If utilization rates

are to be maintained or increased, continuing

work is needed to expand the use of this CUB

in its current applications and to develop new

ways to utilize this important product.

FGD Material

In 2004, just under 12 million tons of

synthetic gypsum were produced in U.S.

FGD systems, and over 9 million tons were

sold. Of product sold, over 8 million tons

went into wallboard.

Because of its purity, which ranges from

96 to 99 percent, the CaSO4 · 2H2O produced

in FGD systems competes effectively with

natural gypsum. Some wallboard producers

have built manufacturing plants near power

plants. When the gypsum is to be used in a

remote wallboard plant, transportation costs

are critical.

16

Conversely, approximately 17.5 million

tons of CaSO3 FGD material were produced

in 2004, but less than 7 percent found a

market, primarily in structural fills and

mining applications. It would be relatively

easy to convert this material to gypsum if

the market would support it. Conversion of

all CaSO3 FGD material would nearly triple

current gypsum production to almost

30 million tons/year. An almost certain rise

in gypsum production will result from

industry compliance with SO2 emission

restrictions embodied in EPA’s Clean Air

Interstate Rule (CAIR). CAIR is expected to

greatly increase the number of plants

equipped with wet FGD systems, which in

turn will substantially increase the amount

of available FGD gypsum.

Because the United States uses a total of

only 39 million tons of gypsum/year, and

given the constraint of transportation costs,

it is unlikely that current uses can effectively

absorb all FGD material in the future. To

fully utilize future production, development

of other potential markets must continue,

including agriculture, gypsum cement, paper,

plastics, pharmaceuticals, food, adhesives,

and paint.

Fly ash and FGD material can be used as filler in paints.
DOE-Sponsored CUB

Demonstrations

As mentioned earlier, DOE has selected

projects under the PPII and CCPI programs

that will demonstrate effective use of CUBs.

These projects are currently in various stages

of development.

Western Greenbrier

One of the DOE-sponsored projects

intended to increase the use of CUBs is the

CCPI project being conducted by Western

Greenbrier Co-Generation, LLC. This

project will co-generate electric power and

steam for export to nearby users, as well as

produce cement from a portion of the ash

from the combustion system.

The Western Greenbrier project, to be

located in Rainelle, WV, will produce

75 megawatts (MW) of electric power while

burning beneficiated waste coal. The waste

coal will be obtained from the 4-million ton

Anjean waste coal pile. The combustion

system will be a circulating fluidized bed

(CFB). Limestone will be injected into the

bed to control SO2. The limestone will be

converted to lime in the CFB. SO2 removal

will be enhanced with a spray dryer

absorber (SDA). Particulate matter will be

controlled in a pulse jet baghouse located

downstream of the SDA. A portion of the

fly ash/lime mixture removed by the

baghouse will be hydrated and recycled.

The balance will be used for remediation

of the acid runoff from the Anjean waste

coal pile.

Spent bed material (lime and ash) will be

processed in a horizontal kiln to produce

clinker, which will then be crushed to

produce a fast-setting, high-strength cement.

University of Kentucky

Another CCPI project that will

demonstrate ash processing is being

sponsored by the University of Kentucky.

Collaborators in this project are CEMEX

USA and LG&E Corporation, the parent of

Kentucky Utilities (KU). The demonstration

will be carried out at KU’s Ghent Power

Station. The technology being demonstrated

will process the ash from a boiler and

convert it all into saleable products. The

demonstration will also use the plant’s ash

pond as a feed source during boiler outages

or when demand for the ash product is high.

17

The process moves the ash through a series

of separation equipment that includes screens,

crushers, hydraulic classifiers, concentrating

spirals, sieve bends, flotation cells, and dryers.

The end result is a series of products that

completely utilize the boiler ash. These

products are pozzolan, lightweight aggregate,

fill-sand, unburned carbon, and cenospheres.

Light-weight concrete block made with CUBs.

(Photo courtesy of FlexCrete Building Systems, LC.)
Universal Aggregates

This PPII project is being conducted by

Universal Aggregates, LLC, at the

Birchwood Power Facility in King George

County, VA. This demonstration will

transform 115,000 tons/year of spray dryer

solids into 167,000 tons/year of lightweight

aggregates that can be used to manufacture

light- and medium-weight masonry blocks.

In this process, spray dryer ash is mixed

with water and other recycled products and

fed to a mixer that produces a moist,

granular material. The product from the

mixer is fed directly to an extruder that

produces short, soft, wet extrusions (green

pellets). These are sent to a slow-turning

tumbler where the green pellets are mixed

with a dry embedding material. The

embedding material coats the green pellets

to keep them from agglomerating and to fill

voids between the pellets to cushion them

during subsequent processing. The green

pellets are then fed to a curing vessel where

they are allowed to cure via cementitious/

pozzolanic reactions. The hardened pellets

are screened to remove fines and embedding

material and sent to storage or to a final

crushing and screening process to generate

the final product.

Other Projects

In addition to these PPII and CCPI

projects, DOE is sponsoring 10 additional

projects under the Combustion Byproducts

Recycling Consortium, which is managed by

the National Energy Technology Laboratory

and the West Virginia University Water

Research Institute. These projects have a total

value of over $1.8 million.

18

Examples of BestPractice Utilization of

CUB Materials

We Energies

We Energies (Wisconsin Electric Power

and Wisconsin Gas LLC) is a leader in CUB

utilization, with more than 98 percent of its

total CUB production (645,000 tons/year)

going to reuse applications. The utility

developed a patented process designed to

remove coal ash from company landfills and

restore the land in accordance with all

applicable regulations. The process includes

identifying a disposal site that has the

appropriate CUBs and excavating cover

materials to access the deposited ash. A

portion of the ash is recovered to determine

loss-on-ignition (LOI) value. If it is cost

effective to do so, the ash material is removed

to a pulverized coal furnace for reburning,

utilizing one of two coal ash beneficiation

processes developed by We Energies. These

processes convert a high-carbon ash into a

more useable and marketable product while

extracting its residual fuel heating value.

The utility also patented a process to

remove ammonia (NH3) compounds from fly

ash. This process is applicable to ash

generated from units equipped with selective

catalytic reduction (SCR) or selective noncatalytic reduction (SNCR) technologies,

which use NH3 to control NOX. The process

involves the application of heat to the ash

using a high-temperature air slide. We

Energies patented two processes related to

the use of fly ash in producing metal matrix

composites (e.g., aluminum casings).

Prototype automotive parts, such as

manifolds and brake drums, have been

produced for testing. In these types of

products, fly ash is used in the composite to

alter the density, hardness, crack propensity,

and mechanical properties of the metal

matrix. These composite materials hold

promise for producing lower cost alloys and

providing a higher value use for fly ash.

We Energies also has a patent (and one

pending) for producing controlled lowstrength material and concrete material that

is less electrically resistant. These

materials have potential applications in the

utility and construction industry for

electrical grounding, lightning protection,

transportation system sensors, and ice

prevention on bridges, sidewalks, and

airport runways.

The utility has also produced a structural

lightweight aggregate that blends a mixture

of fly ash, paper mill sludge, and municipal

wastewater sludge. The process pelletizes

and dries the mixture, then fires the pellets

in a co-current flow rotary kiln to produce

a low-density, ceramic aggregate. From

1994 to 2000, We Energies owned and

operated a commercial-scale pilot plant for

the production of this product.

Great River Energy

Great River Energy markets fly ash from

the Coal Creek Power Station, a 1,100-MW

plant, located in Underwood, ND, and the

Stanton Station, a 180-MW plant located

near Stanton, ND. Sales of fly ash in 2004

from the Coal Creek Power Station are

projected to have been about 390,000 tons

out of the 440,000 tons produced. A

significant portion of the fly ash marketed

from both plants is mixed with cement to

make concrete that is stronger and more

durable than concrete made with cement

alone. In addition, the fly ash from these

plants is being used by the Amerada Hess

Corporation to restore oil production sites

in North Dakota after oil rigs are removed.

It is also used in manufacturing FlexCrete

(an aerated concrete) that will be used to help

construct the National Energy Technology

Training and Education Center at Bismarck

State College. The fly ash is also being tested

in new product development for ceramic tiles

and a spray product to protect and extend

the life of wooden power transmission poles.
Charah Inc.

Charah has explored new ways to bag

concrete mix to address issues of cleanliness

and container damage loss to appeal to bigbox retailers, who are the largest sellers of

these products. Working with Automatic

Packaging Machinery of Atlanta, GA, and

Concetti of Rome, Italy, Charah developed

a method to successfully place its CUBbased concrete mix into totally sealed

plastic bags fitted with two handles. In

addition, the plastic bags are more durable

than paper bags. These innovations will

eliminate leakage problems experienced by

retailers and make the product more

appealing to consumers.

Charah built a manufacturing plant in

Virginia that started production in January

of 2005. This plant includes automated,

state-of-the-art equipment and will have the

capacity to annually produce six million

bags of the CUB-based concrete mix. Over

the next three years, Charah plans to build

seven additional manufacturing plants to

utilize ash resources throughout the United

States.

EERC

The University of North Dakota Energy

and Environmental Research Center (EERC)

has the country’s most extensive research

program focused on the release of mercury

via leachates and vapor from CUBs impacted

by mercury emission controls. EERC has

developed the following technologies:

• Methods for determining the direct

leachability of mercury from CUBs

• Methods for evaluating vapor-phase

transport of mercury

• A method to evaluate the release of mercury

from CUBs at elevated temperatures (up

to 750 °C) in real time

• Experimental protocols to evaluate the

effect of microbiological activity on CUB

leachate.

19

The DOE Clean Coal Technology Programs

The DOE commitment to clean coal development has progressed through three

phases. First was the Clean Coal Technology Demonstration Program (CCTDP),

a model of government and industry cooperation that advanced DOE’s mission

to foster secure and reliable energy systems.

With 33 of its 34 active projects completed, the CCTDP has yielded technologies

that provide a foundation for meeting future energy demands and utilizing the

vast U.S. reserves of coal in an environmentally sound manner. Begun in 1985,

the CCTDP represents a total investment value of nearly $3.3 billion. DOE’s

share of the total cost is about $1.3 billion, or approximately 40 percent. The

projects’ industrial participants (i.e., non-DOE) have provided the remainder,

about $2.0 billion.

Two follow-on programs have been developed that build on the successes

of the CCTDP and are patterned after it. The Power Plant Improvement

Initiative (PPII) is a cost-shared program directed toward improved reliability

and environmental performance of the nation’s coal-burning power plants.

Authorized by the U.S. Congress in 2001, PPII involves six projects that

focus on technologies enabling coal-fired power plants to meet increasingly

stringent environmental regulations at the lowest possible cost.

The Clean Coal Power Initiative (CCPI), authorized in 2002, is aimed at

accelerating commercial deployment of advanced technologies to ensure the

nation will continue to have clean, reliable, and affordable electricity. Total Federal

funding will equal up to $2 billion over 10 years, with a matching cost share by

industrial participants of at least 50 percent. To date, nine CCPI projects are

either active or in negotiation.
LCRA

In 2004, the Lower Colorado River

Authority (LCRA) achieved a utilization

rate of nearly 150 percent of current

production of FGD CUBs by using material

that was deposited in landfills years ago.

LCRA plans to install scrubbers on Units 1

and 2 at the Fayette Power Project by 2012

and projects that its market will

accommodate the additional volume of

FGD by-products that it anticipates

generating in the near future.

LCRA’s bottom ash uses include

production of road-base materials (bottom

ash mixed with fly ash) and brick

manufacturing. Until 2002, LCRA’s

utilization rates of bottom ash averaged

nearly 50 percent. By 2004, LCRA pushed

its utilization rate to over 100 percent, again

using stored material produced in earlier

years to make up the difference. The

increased use is primarily due to a higher

local demand in surrounding counties for

road-base material. In addition, the demand

for bottom ash as an ingredient in brick

increased when a new brick plant opened

in the area. LCRA’s fly ash use, primarily

in ready-mix concrete, road stabilization,

and road-base mixtures, has also seen an

increase beyond 100 percent.

Kansas City Power and Light;

Lafarge North America; and the

University of Missouri, Kansas City

The partners are testing the “Full Depth

Cold In-Place Recycling of Asphalt

Pavement.” This process is used to

rehabilitate low-volume rural roads by

recycling existing asphalt pavement and base

materials in place, instead of hauling them

away and bringing virgin materials to the site.

The old road is ground up and left in place.

Self-cementing (Class C) fly ash and water

are then mixed in, and the blend is compacted

into a new road base.

20

In ancient times the Romans added volcanic ash to concrete to strengthen structures and roads.

CUBs are used to enhance modern road construction.
PMET

Pittsburgh Mineral and Environmental

Technology (PMET) developed and patented

the innovative Brixx Technology to produce

building products. The process produces

stand-alone building products from CUBs,

including both fly ash and bottom ash. Unlike

many concrete applications, the Brixx

process can utilize fly ash with LOI

exceeding 3 percent. The process consists of

mixing the raw materials, pressing the

mixture into desired shapes, and curing the

resulting product. The process produces

tobormorite (a calcium silicate hydrate)

crystals in the Brixx product that result in a

strong, weather-resistant material. PMET has

taken this technology from a laboratory-scale

process to the pilot scale. Currently, PMET

is producing paving brick as a demonstration

project for a Pennsylvania Department of

Environmental Protection-sponsored Energy

Harvest grant.

The fly ash used in this project has an LOI

of 6.3 percent, which is too high to use as an

additive in concrete. The Brixx paving bricks

have a compressive strength that exceeds

ASTM standards. For a full-scale plant, energy

consumption is expected to be 430,000 Btu/

ton of product, which is 67 percent less energy

than a modern clay brick high-efficiency kiln.

Production costs are expected to be

approximately $0.11/piece, compared to an

estimated selling price of $0.20. PMET

estimates that a plant producing 13.6 million

paving bricks/year would have a payback time

of two years.

21

Xcel Energy and Lafarge North

America

During the spring of 2002, Xcel Energy

and Lafarge North America demonstrated use

of fly ash alongside other materials

(including lime and oil emulsions) on a trial

highway project in Randall County, TX. The

paving contractor used approximately

200 tons of CUB material to stabilize the road

base. The fly ash performance on this project

was strong compared to the alternative

materials, and Lafarge has seen geotechnical

applications grow from 20 percent of the

stabilization work in the Amarillo market in

2002 to 90 percent of the market today.

The success of Xcel Energy and

Lafarge’s success in the traditional and

nontraditional CUB markets in Texas has

resulted in the beneficial use of all of the

500,000 tons of CUBs produced annually

at Xcel’s Harrington and Tolk power

stations. Xcel Energy estimates that in 2003,

15,865 tons of these CUBs were used in

Texas stabilization projects. Assuming

that 75 percent of fly ash used for soil

stabilization replaces the use of lime, the

corresponding ratio of CUB to lime use is

about 2:1. With an emission factor for lime

manufacture of 0.17 metric tonnes of carbon

equivalent (MTCE)/ton, then greenhouse

gas emissions reduction attributable to this

CUB use in stabilization projects is

1,350 MTCE/year.

CUBs are used in a range of construction materials, including masonry products.
Factors Limiting the

Use of CUBs

Unburned Carbon on Fly Ash

Increasingly strict limits on U.S. NOX

emissions have led to the widespread use

of low-NOX burners, reburning, and overfire

air. Often these strategies impair complete

coal combustion and produce high-carbon

fly ash, which is unsuitable for use in

cement manufacturing. The excessive

carbon adsorbs concrete’s air-entraining

agent, which impacts the setting process,

causes air entrainment problems, and

reduces the material’s strength and

durability, especially during freeze-thaw

conditions.

In some cases, careful design and

operation of low-NOX combustion systems

can mitigate the problem of excessive

carbon. Several organizations have also

developed processes to separate the

unburned carbon from the fly ash or

developed cement additives to block

adsorption of the air-entraining chemicals

by the carbon. The University of Kentucky

Center for Applied Energy Research is

currently demonstrating a DOE-sponsored

CCPI project that addresses the former

application.

Ammonia Deposition on Fly Ash

Two other NOX-reduction technologies—

SCR and SNCR—introduce NH3 into the

flue gas. Unreacted NH3, referred to as

ammonia slip, contaminates the system’s fly

ash via adsorption or other mechanisms. This

effect can be detrimental to both utilization

and disposal of the ash.

In the manufacture of building materials,

fly ash must meet permissible limits of

ammonia content based on exposure limits

for employees and product performance.

Even if exposure limits are not exceeded,

ammonia can present problems for sensitive

individuals.

If the ash is placed in a landfill, odor

becomes a factor. Further, in landfills,

rainwater can leach ammonia along with

other components of ash, resulting in

violation of groundwater pollution

regulations.

These effects must be taken into account

in establishing SCR/SNCR operations, and

several thermal and chemical techniques

have been developed to counteract the effects

of ammonia slip. One process subjects the

fly ash to an additional FBC step to remove

both the unburned carbon and the residual

ammonia. Another process treats the fly ash

with an alkali, such as lime, to release and

recover the ammonia. In addition, several

methods have been developed to remove

ammonia and other pollutants from the

wastewater that results from exposure of fly

ash in landfills to rainwater.

22

Increasing CUB Utilization

In 2003, the ash industry, in partnership with EPA, DOE, and the

Federal Highway Administration, established the Coal Combustion

Products Partnership (C2P2). This effort has been successful in

making end-users, specifiers, regulators, and others aware of how

CUBs can enhance highway and construction activities.

C2P2 has also recognized a number of organizations for their

initiatives to increase the use of CUBs. Awardees exemplify best

practices for promoting the commercial utilization of CUBs and

demonstrating the environmental benefits that can result.

In mid-2005, a number of C2P2’s founders began working on a

new program, the Green Highways Partnership. The partnership

combines public and private efforts to integrate transportation

planning with environmental protection. This includes addressing

such factors as watershed protection, ecosystem management,

and the use and reuse of recycled industrial materials.

By looking at the design, planning, construction, operation, and

maintenance of transportation systems in the broadest

environmental context, there will be less impact on the

environment and many opportunities for collaborative

partnerships. Coal ash and other industrial by-products can

contribute to the greening of America’s highways by conserving

natural materials, reducing greenhouse gas emissions, and lowering

overall costs.
23

ACAA Coal Utilization By-Product Data for 2004—All quantities are 1000s of tons. 

CUBs used for: Fly Ash 

Bottom 

Ash 

Boiler 

Slag 

FGD 

Gypsum 

Wet 

FGD 

Product 

Dry 

FGD 

Product 

FGD 

Other 

FBC 

Ash 

Concrete/concrete 

products/grout 14,122 789 0 291 0 37 0 0 

Structure/fills 

 embankments 4,685 3,065 7 0 267 0 0 62 

Cement/raw feed for 

cement clinker 2,345 615 34 449 39 0 0 0 

Road base/ 

subbase/pavement 488 1,092 7 0 0 0 0 0 

Snow & ice control 6 830 88 0 0 0 0 0 

Agriculture 52 19 0 131 11 3 0 0 

Aggregate 8 409 38 0 0 3 0 0 

Flowable fill 180 0 0 0 0 11 0 0 

Mineral filler in 

asphalt 90 0 40 0 0 0 0 0 

Wallboard 0 0 0 8,148 0 0 0 0 

Waste stabilization/ 

solidification 2442 257 5 0 0 0 0 71 

Mining applications 1,113 40 0 0 282 123 0 135 

Blasting grit/ 

roof granules 0 70 1,747 0 0 0 0 0 

Soil modification/ 

stabilization 501 21 0 0 0 0 0 190 

Miscellaneous 2,037 944 8 25 597 0 3 16 

Total used 28,069 8,152 1,973 9,045 1,196 177 3 473 

Total produced 70,800 17,200 2,202 11,950 17,500 1,829 115 867 

Percent used 39.7 47.4 89.6 75.7 6.8 9.7 2.9 54.6 
24

Mercury

Recent regulations to control mercury

emissions in stack gases could also have a

deleterious effect on the utilization of CUBs.

One method likely to be widely used for

mercury control is the injection of powdered,

activated carbon into the flue gas. Currently,

the carbon is removed along with the fly ash

using standard fly ash removal equipment.

This results in ash contaminated with high

carbon levels.

We Energies Inc. is conducting a CCPI

project at its Presque Isle Power Plant to

demonstrate EPRI’s TOXECONTM mercurycontrol process. Using this process, the bulk

of the fly ash is removed by existing ESPs

before carbon is injected into the system. The

carbon is later removed, along with any

residual ash, via a baghouse installed

downstream of the ESP.

Wet FGD processes can also be effective

for mercury removal, especially if the

mercury in the flue gas is in the oxidized state

when it enters the FGD system. There is

currently some interest in enhancing these

processes to achieve higher levels of mercury

removal. One concern is the possibility of

FGD by-products containing elevated levels

of mercury. However, tests to date indicate

that mercury contamination will not be a

problem for either the disposal or

constructive use of these CUBs.

A second concern is the re-release of

gaseous mercury during the manufacture of

wallboard, cement, and other products that

contain FGD CUBs. The Innovations for

Existing Plants program of DOE’s National

Energy Technology Laboratory is currently

investigating the extent to which such rereleases of mercury may occur.

To Receive Additional

Information

To be placed on the Department

of Energy’s distribution list for

future information on the Clean

Coal Demonstration Programs,

the projects they are financing, or

other Fossil Energy Programs,

please contact:

John L. Grasser

Director, Office of Communication

FE-5/Forrestal Building

U.S. Department of Energy

1000 Independence Ave., SW

Washington, DC 20585

202-586-6803

202-586-5146 fax

john.grasser@hq.doe.gov

David J. Anna

Office of Public Affairs Coordination

U.S. Department of Energy

National Energy Technology

Laboratory

P.O. Box 10940

Pittsburgh, PA 15236-0940

412-386-4646

412-386-6195 fax

david.anna@netl.doe.gov

Agriculture is a potentially significant market for gypsum and other CUBs.
25

Contacts for CCT

Projects and U.S.

DOE CCT Program

Gene Kight

FE-20/Germantown Building

U.S. Department of Energy

1000 Independence Ave., S.W.

Washington, DC 20585-1290

301-903-2624

301-903-9301 fax

gene.kight@hq.doe.gov

Ronald L. Cutright

Director

Advanced Energy Systems

Division

National Energy Technology

Laboratory

P.O. Box 880

Morgantown, WV 26507-0880

304-285-4012

304-285-4403 fax

This report is available on

the Internet at:

www.netl.doe.gov

Conclusions

CUB reuse carries with it many economic

and environmental advantages, including

cost savings to the power industry,

conservation of natural resources and landfill

disposal space, and reduced CO2 emissions.

The challenges are to ensure that CUBs

produced are available and salable and

continue to find profitable market outlets.

Through research and increased public

awareness, these challenges are being

addressed by government and private

stakeholders. The quantities of CUBs

generated are increasing, but the utilization

of CUBs is increasing faster.

We have nearly reached the goal of

50 percent utilization to be achieved by 2010.

With continued product and market

development, this goal will be met and

exceeded, and our nation will have come a

long way in the responsible stewardship of

its CUBs.
List of Acronyms and Abbreviations

ACAA ........................... American Coal Ash Association

ASTM ........................... American Society for Testing and Materials

CaSO3 .......................................... calcium sulfite

CaSO4 .......................................... calcium sulfate

CaSO4•2H20 .................. gypsum

CCPs ............................. coal combustion products

CCPI ............................. Clean Coal Power Initiative

CCWs............................ coal combustion wastes

CFB ............................... circulating fluid bed

CO2 ................................................ carbon dioxide

CCTDP .........................Clean Coal Technology Demonstration Program

CUBs ............................ Coal Utilization By-Products

DOE .............................. U.S. Department of Energy

EERC ............................ University of North Dakota Energy and Environmental Research Center

EPA ............................... U.S. Environmental Protection Agency

EPRI ............................. Electric Power Research Institute

ESP ............................... electrostatic precipitator

FBC ............................... fluidized bed combustion

FGD .............................. flue gas desulfurization

KU ................................ Kentucky Utilities

LCRA ........................... Lower Colorado River Authority

LOI ............................... loss on ignition

MTCE ........................... metric tonnes of carbon equivalent

MW ............................... megawatts of electric power

NH3 ............................................... ammonia

NOX .............................................. nitrogen oxides

PMET ........................... Pittsburgh Mineral and Environmental Technology, Inc.

PPII ............................... Power Plant Improvement Initiative

RCRA ........................... Resource Conservation and Recovery Act

RD................................. regulatory determination

RTC ............................... Report to Congress

SCR ............................... selective catalytic reduction

SDA .............................. spray dryer absorber

SNCR............................ selective non-catalytic reduction

SO2 ................................................sulfur dioxide

USGS ............................ United States Geological Survey

26
Bibliography

American Coal Ash Association, Coal Ash:

Innovative Applications of Coal Combustion

Products (CCPs), 1998

American Coal Ash Association, 2004 data at http://

www.ACAA-USA.org

American Coal Council,

http://americancoalcouncil.org

Coal Combustion Products Partnership (C2

P2),

www.epa.gov/epaoswer/osw/conserve/c2p2/

index.htm, www.epa.gov/rcc/c2p2/pubs/pmet.pdf

Combustion Byproducts Recycling Consortium,

wvwri.nrcce.wvu.edu/programs/cbrc

Ellison, W., New Frontiers for Byproduct Gypsum,

Internal report prepared for

U.S. DOE, February 1989

EPRI 2006 Portfolio, P078.002, Technologies and

Information to Increase Use of All CCPs,

www.epri.com/portfolio/

product.aspx?id=1213&area=25&type=10

Groves, A.W., Gypsum and Anhydrite, Overseas

Geological Surveys, Her Majesty’s Stationery

Office, 1958

Kelly, T. and Van Oss, H.G., U.S. Geological Survey,

Coal Combustion Products Statistics, June 2004;

http://minerals.usgs/gov/minerals/pubs/commodity/

coal/#pubs

National Research Council, Managing Coal

Combustion Residues in Mines, March 2006

Ramme, B. and Tharaniyil, M., Coal Combustion

Products Utilization Handbook, 2nd Edition, 2004,

www.we-energies.com/environmental/

ccp_handbook_preface.pdf

U.S. Department of Energy, www.fossil.energy.gov/

programs/powersystems/index.html

U.S. Environmental Protection Agency, Using Coal

Ash in Highway Construction: A Guide to Benefits

and Impacts,

EPA-530-K-05-0002, April 2005

World of Coal Ash, Conference Proceedings,

April 2005, www.worldofcoalash.org/index.html

27

The most common and economical use for fly ash is in the manufacture of

concrete and concrete products.
National Energy

Technology Laboratory

1450 Queen Avenue SW

Albany, OR 97321-2198

541-967-5892

2175 University Avenue South, Suite 201

Fairbanks, AK 99709

907-452-2559

3610 Collins Ferry Road

P.O. Box 880

Morgantown, WV 26507-0880

304-285-4764

626 Cochrans Mill Road

P.O. Box 10940

Pittsburgh, PA 15236-0940

412-386-4687

One West Third Street, Suite 1400

Tulsa, OK 74103-3519

918-699-2000

Visit the NETL website at:

www.netl.doe.gov

Customer Service:

1-800-553-7681

U.S. Department of Energy

Office of Fossil Energy

Printed in the United States on recycled paper

August 2006