Environmental Benefits of Clean Coal Technologies

TOPICAL REPORT NUMBER 18 April 2001

TOPICAL REPORT NUMBER 18

The U.S. Department of Energy

April, 2001

Environmental Benefits of

Clean Coal Technologies

Environmental Benefits of

Clean Coal Technologies

Executive Summary........................................................................................... 1

Background........................................................................................................ 2

Environmental Regulations ............................................................................... 3

SO2 Emissions ............................................................................................... 4

NOx Emissions.............................................................................................. 4

Particulate Emissions .................................................................................... 4

Air Toxics Emissions .................................................................................... 5

Climate Change ............................................................................................. 5

CCT Program Market Sectors ........................................................................... 6

Environmental Progress..................................................................................... 8

Acid Rain Program ........................................................................................ 8

Air Quality Improvements .......................................................................... 10

Additional Environmental Effects............................................................... 12

CCT Participant Comments ........................................................................ 14

EPA Comments ........................................................................................... 14

DOE’s Continuing Role in Environmental Issues ........................................... 16

Track Record of Environmental Progress ....................................................... 18

Bibliography .................................................................................................... 20

Contacts for U.S. DOE CCT Program............................................................. 25

List of Acronyms and Abbreviations .............................................................. 28

1

Executive Summary

The Clean Coal Technology (CCT) Demonstration Program is a government and

industry co-funded 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 the information required for future commercial applications.

The goal of the CCT Program is to furnish the marketplace with a number of advanced, more efficient coal-based

technologies that meet strict environmental

standards. These technologies minimize the

economic and environmental barriers that

limit the full utilization of coal.

Beginning in 1985, a multi-phased effort

consisting of five separate solicitations was

administered by the U.S. Department of

Energy’s (DOE) National Energy Technology Laboratory. The CCT Program has successfully demonstrated a number of coal

utilization technologies that are being applied commercially with beneficial results

to the environment and increased efficiency

in the use of energy.

A major criticism of coal as a fuel source

for power generation is that it produces large

amounts of pollutants, primarily sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter (PM), as well as carbon dioxide

(CO2), which is implicated in global climate

change. This report summarizes the contributions of the CCT Program in achieving significant reductions in emissions of these pollutants.

Uncontrolled SO2 emissions from U.S.

coal-burning power plants could exceed 20

million tons/yr. As a result of controls already in place, SO2 emissions have been

reduced to about 12 million tons/yr. If CCTdeveloped technologies were applied to all

coal-fired boilers, it is estimated that SO2

emissions could be further reduced by another 10 million tons/yr.

Total NOx emissions from coal-fired boilers are about 6.8 million tons/yr, equivalent

to an emissions rate of 0.75 lb/million Btu. If

average NOx emissions were reduced to 0.35

lb/million Btu, a goal easily reached using

demonstrated technologies, total NOx emissions would be reduced by an additional 3.6

million tons/yr to approximately 3.2 million

tons/yr.

CCT Program successes include:

• Advanced technologies that have dramatically improved the economic and

environmental performance of flue gas

desulfurization systems for SO2 control. By-product gypsum is now recovered for sale as wallboard, thereby

eliminating a major waste disposal

problem.

• NOx reduction technologies that have

been or are being retrofitted to a large

segment of the nation’s coal-fired

power generating capacity. Low-NOx

burners now cost a fraction of the cost

of NOx pollution controls available in

the 1980s.

• New power generation systems now in

commercial operation, based on coal

gasification. These systems are among

the cleanest power plants in the world,

with extremely low emissions of SO2,

NOx, and particulates.

The Healy power plant is located near

the Denali National Park and Preserve,

an environmentally sensitive area in

Alaska.
2

Environmental

Benefits of Clean

Coal Technologies

Background

The Clean Coal Technology (CCT) Demonstration Program, sponsored by the U.S.

Department of Energy (DOE) and administered by the National Energy Technology

Laboratory (NETL), has been underway

since 1985. Its goal is to develop innovative,

environmentally friendly coal utilization processes for the world energy marketplace.

The CCT Program involves a series of demonstration projects that provide data for design, construction, operation, and technical/

economic evaluation of full-scale commercial facilities.

The CCT Program represents an investment of over $5 billion in the demonstration of advanced coal-based

technologies, with industry and state

governments providing a significant

share — 66% — of the funding. With

26 of the 38 projects having completed

operations, the CCT Program has

yielded a variety of processes that are

capable of meeting existing and emerging environmental regulations and competing economically in a deregulated

electric power marketplace.
3

Clean Coal for a Better Tomorrow

Environmental

Regulations

The Clean Air Act Amendments (CAAA) of

1990 is one of the most complex and comprehensive pieces of environmental legislation ever written. It authorized the Environmental Protection

Agency (EPA) to establish regulations controlling

emissions from a variety of stationary sources,

including coal-fired boilers.

The CCT Program has introduced a variety of

options to policy-making bodies by providing data

from cutting-edge technologies to aid in formulating regulatory decisions. As an example, DOE and

the industrial participants in several CCT projects

have provided EPA with data to help establish

realistic emissions targets for coal-fired boilers.

The CAAA addresses six major substances, referred to as

criteria pollutants: carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), particulate matter (PM), and

sulfur dioxide (SO2). Ozone is not emitted directly into the

air, but is formed by interaction of volatile organic compounds (VOCs) and nitrogen oxides (NOx). Although NO2

is a criteria pollutant, the CAAA has focused on NOx, owing

to its direct connection with ozone formation.

The portions of the CAAA of greatest relevance to the

CCT Program are Title I and Title IV. Title I addresses the

issue of ozone in ambient air, and targets NOx emissions

reduction as a means of achieving compliance. Title IV,

referred to as the Acid Rain Program, addresses emissions

of SO2 and NOx.
4

SO2 Emissions

SO2 is formed during coal combustion by

oxidation of sulfur in the coal. SO2 control is

achieved by removing it from the flue gas.

Even before enactment of the CAAA, the

CCT Program was cognizant of the likely

effects of the anticipated regulations on electric power generation. Several projects in

the CCT Program were conducted at units

designated as Phase I units under Title IV,

which were required to meet SO2 reductions

by January 1, 1995. CCT Program projects

installed at Phase I units successfully reduced SO2 emissions using advanced flue

gas desulfurization (FGD) processes.

With the arrival of the January 1, 2000

deadline for Phase II of Title IV, the CCT

Program had developed a portfolio of technologies to help industry meet the more

stringent SO2 emission limits. Unit operators now have the option of either meeting

SO2 reduction requirements or exceeding

them to generate SO2 credits that can be sold

in the emissions credit market.

NOx Emissions

NOx is formed from oxidation of nitrogen contained within the coal (fuel NOx)

and oxidation of the nitrogen in the air at

high temperatures of combustion (thermal

NOx).

NOx became the focus of a series of regulatory actions to severely limit emissions after

being identified as a source of both acid rain

(targeted under Title IV) and urban smog

(targeted under Title I). Coal-fired boilers

represent a primary source of NOx emissions and a specific target of regulatory

action. Although combustion of gas and oil

also results in NOx emissions, and mobile

sources contribute significantly to this problem, the focus of the CCT Program is control

of pollution resulting from coal combustion/

gasification.

 The Acid Rain Program (Title IV of the

CAAA) calls for major reductions in NOx

emissions. The CCT Program has successfully demonstrated control techniques that

are applicable to all major boiler types. Furthermore, these technologies are applicable

not only to Title IV but also to Title I NOx

reductions.

The issue of ozone nonattainment, covered under Title I, took on new proportions

in 1997 as EPA issued a call for state implementation plans (SIP) to 22 states and the

District of Columbia. These plans required

action to reduce regional transport of pollutants that contribute to ozone nonattainment

in the U.S. Northeast. The SIP Call requires

the 23 affected jurisdictions to reduce power

plant NOx emissions by 85% from 1990

rates or achieve a 0.15 lb/million Btu emission rate. These reductions were to be

achieved by the target compliance date of

May 2003.

In addition, EPA tightened the New

Source Performance Standards (NSPS) for

electric and industrial boilers built or modified after July 9, 1997.

Particulate Emissions

Particulate matter is the general term for

a mixture of solid particles and liquid droplets found in the atmosphere. Some particles

are large enough to be seen as soot or smoke.

Others are so small that they can be detected

only with an electron microscope. PM2.5

describes the fine particles that are less than

or equal to 2.5 microns (μ) in diameter. A

micron is one millionth of a meter, or about

0.00004 inch. Coarse particles are those

greater than 2.5 μ and less than 10 μ in

diameter. The latter are referred to as PM10.

PM originates from many different stationary and mobile sources as well as natural

sources. Fine particles result from fuel combustion in motor vehicles, during power

generation, and in industrial facilities. Coarse

particles are generally emitted from sources

such as vehicles traveling on unpaved roads,

materials handling, crushing, and grinding

operations, as well as windblown dust. Some

particles are emitted directly from their

SO2 Formation

All coals contain sulfur. Some of

this sulfur, known as organic sulfur,

is intimately associated within the

coal matrix. The rest of the sulfur,

in the form of pyrites or sulfates, is

associated with the mineral matter.

High-sulfur bituminous coals contain 1-4% sulfur, whereas low-sulfur Western coals may have sulfur

content below 1%. Upon combustion, most of the sulfur is converted

to sulfur dioxide (SO2), with a small

amount being further oxidized to

sulfur trioxide (SO3).
5

sources, such as smokestacks and cars. In other

cases, gases such as SO2, NOx, and volatile

organic compounds (VOCs) interact with other

compounds in the air to form fine particles.

Their chemical and physical compositions

vary depending on location, time of year, and

weather.

SO2 reduction may contribute to meeting

emissions requirements for PM2.5 because some

sulfur species are also included in PM2.5.

Air Toxics Emissions

Air toxics is another important area of environmental concern addressed by the CCT Program. Under Title I of the CAAA, EPA is

responsible for determining the hazards to public health posed by 189 identified hazardous air

pollutants (HAPs). The CCT Program has made

a significant contribution to a better understanding of this issue from power plant emissions by monitoring HAPs from several project

sites. The results of these and other studies

have significantly mitigated concerns about

HAP emissions from coal-fired power plants

and focused attention on only a few flue gas

constituents. EPA has recently determined that

emissions of mercury, a HAP of major concern, will require control. Regulations are to be

proposed by the year 2003, with implementation by 2005.

Climate Change

Global climate change is one of the primary

environmental concerns of the 21st century.

Response to climate change could dictate fundamental changes in the ways that we generate

and use energy. Such measures as energy efficiency improvements, forest management options, and renewable energy applications are

potentially important methods for reducing

greenhouse gas (GHG) emissions in the short to

medium term.

The CCT Program addresses climate change

concerns. Advanced coal-based technologies

being demonstrated in the CCT Program offer

utilities an option to make substantial reductions in GHG emissions through enhanced

efficiency of first-generation systems.

SO2 Emissions Control Technologies

Wet Scrubbing

Wet scrubbing or flue gas desulfurization (FGD) is the most frequently used technology for post-combustion control of SO2 emissions. Wet FGD is frequently used with existing boilers and has the

advantage that no modifications either to the boiler or to the particulate emission control device are required. Typically, the flue gas is

contacted with an aqueous slurry of limestone (CaCO3) in a countercurrent absorber, or scrubber. The SO2 reacts to form CaSO3 which

is then oxidized to CaSO4 (gypsum).

Allowable gas flow per unit cross sectional area is determined by

the mass transfer characteristics of the system. This determines the

diameter of the scrubber. These vessels and the accompanying

equipment used for slurry recycle, gypsum dewatering, and product

conveyance tend to be quite large. Some variations of this technology

produce high quality gypsum for sale. Less pure waste product may

be sold for use in cement production. If neither of these options is

practiced, the scrubber waste must be disposed of in a sludge

pond or similar facility.

Dry Sorbent Injection (DSI)

In DSI, a reactive calcium- or sodium-based sorbent is injected into

the economizer or flue gas duct to react directly with the SO2 in the

flue gas. The two most common calcium-based sorbents are limestone and slaked lime, Ca(OH)2. Limestone, which generally requires

a higher reaction temperature, is usually injected as a dry powder.

Slaked lime, on the other hand, is usually handled as a slurry, which

dries as soon as it is injected into the hot flue gas. Upon injection,

Ca(OH)2 immediately begins to dehydrate. The escaping water vapor

creates internal pores that provide access for SO2 diffusion into the

interior of the particles. The CaO produced by dehydration reacts with

SO2 to give CaSO3, which can be oxidized to CaSO4.

Typical sodium-based sorbents are sodium bicarbonate (NaHCO3),

sodium sesquicarbonate (NaHCO3•Na2CO3•2H2O), and sodium carbonate (Na2CO3). Below 300 oF, NaHCO3 reacts immediately with

SO2 to form Na2SO3. At higher temperatures, NaHCO3 decomposes

to Na2CO3 before reacting with SO2. As water and CO2 are given off

by the sorbent particles, additional surface area becomes available for

reaction with SO2. Although CO2 is a product of CaCO3, NaHCO3,

and Na2CO3 decomposition, the amount generated is minimal compared to that already present in the flue gas.

In some cases, flue gas humidification may be necessary for proper

operation of the downstream particulate removal system.

Production of Sulfuric Acid

In this process option, the SO2 in the flue gas is first converted to

SO3 by passing the flue gas over a catalyst bed. The SO3 reacts with

water to form sulfuric acid, which is recovered for sale.
6

CCT Program Market Sectors

This report focuses primarily on the

success of the CCT Program in reducing

emissions of SO2, NOx, and particulates.

CCT demonstration projects have covered

a wide variety of processes, addressing

four market sectors:

Environmental Controls

These technologies were developed to

remove or prevent the formation of SO2,

NOx, and particulates when coal is burned

to generate electric power using conventional technologies.

Advanced Power Generation

These are advanced, coal-fired technologies designed to replace conventional

coal-fired power generation. They are characterized by high thermal efficiency, very

low pollutant emissions, reduced CO2

emissions, few solid waste problems, and

enhanced economics. Three major areas of

technology are considered to be advanced

electric power generators:

• Fluidized-Bed Combustion (FBC)

• Integrated Gasification Combined Cycle

(IGCC)

• Advanced Combustion/Heat Engines.

FBC reduces emissions of SO2 and NOx

by controlling combustion parameters and

by injecting a sorbent into the combustion

chamber along with the coal. Crushed coal

mixed with the sorbent (e.g. calcium carbonate) is fluidized on jets of air in the combustion chamber. Sulfur released from the coal

as SO2 is captured by the sorbent to form a

solid calcium compound that is removed with

the ash. Greater than 90% SO2 removal can

be achieved. FBCs operate at a much lower

temperature than that of conventional pulverized-coal boilers, greatly reducing the

amount of thermal NOx formed.

2,500,000

Emissions Scale

(In Tons)

2,000,000

1,500,000

1,000,000

500,000

0

1980 1990 1996 1997

1997 1996 1990 1980

20

15

10

5

0

(Millions Tons)

Key

Annual S2O Emissions

SO2 emissions reductions are occurring where they are needed –

in some of the highest emitting areas of the country.
7

Responding to New Marketplace Realities

DOE programs developing coal utilization technologies and power generation systems are responding to dramatic changes occurring in the energy marketplace. Energy industry deregulation is creating intense

cost-reduction pressures on power producers. DOE programs are geared

to provide these producers with cost-competitive solutions to environmental

challenges. At the same time, natural gas, electric, water, and oil companies are merging into larger business entities that are investing less in research. Therefore, DOE programs must leverage limited private-sector

research dollars more effectively than ever. Deregulation is also creating

new markets for energy

concepts that use natural gas, coal, and biomass fuels to generate a

mix of products that include electricity, liquid

fuels, and chemicals,

with virtually zero environmental impact.

IGCC systems involve gasification of coal,

cleaning the gas, and combusting it in a gas

turbine generator to produce electricity. Residual

heat in the exhaust gas from the gas turbine is

recovered in a heat recovery boiler as steam,

which can be used to produce additional electricity in a steam turbine generator. IGCC systems are

among the cleanest and most efficient of the

emerging clean coal technologies. Sulfur, nitrogen compounds, and particulates are removed

before the gas is burned in the gas turbine.

In the gasifier, the sulfur in the coal is released

in the form of hydrogen sulfide (H2S), which is

readily removed by commercially available processes. By-products are salable sulfur or sulfuric

acid. Sulfur removal exceeds 99.9%, and thermal

efficiencies of over 50% can be achieved. High

levels of nitrogen removal are also possible. Some

of the coal’s nitrogen is converted to NH3, which

can be almost totally removed by established

chemical processes. NOx formed in the gas turbine can be held to well within allowable levels by

staged combustion or by adding moisture to control flame temperature.

Advanced combustion/heat engines include

slagging combustors that are designed to remove

coal ash as molten slag in the combustor rather

than the furnace, and coal-fired diesel engines.

These engines use either a coal-oil or coal-water

slurry fuel to drive an electric generation system.

Coal Processing for Clean Fuels

This area includes a variety of technologies

designed to produce solid and clean liquid fuels

having high energy density and low sulfur.

Industrial Applications

This category includes a steel-making process

in which coal replaces a portion of the coke

traditionally used in iron-making furnaces. It also

includes a process to remove SO2 from the flue

gas produced in cement manufacture.

Air Quality Act of 1967 ESP’s or baghouses required for coal-fired power plants

New Source Performance Standards established for NOx, SO2, and PM

PM emissions limits for new coal-fired boilers reduced by 70%

Acid Rain program initiated, resulting in widespread switching to low-sulfur 

coal and installation of low-NOx burners

Coal Combustion By-Products (fly ash, bottom ash, boiler slag and 

FGD residue) cited by EPA as non-hazardous solid wastes, with disposal 

and use to be regulated by states under RCRA Subtitle D

Fine Particulates cited by EPA as a health hazard, corresponding 

primary PM, NOx and/or SO2 emissions to be reduced by 70% in 

19 eastern states by 2007

Ground-Level Ozone, NOx emissions to be reduced by 70% 

in 19 eastern states by 2007

Mercury EPA report to Congress suggests a plausible link between 

mercury emissions from power plants and contamination on fish

Information Collection Request, EPA requires certain U.S. 

coal utilities to sample coal feedstock and stack emissions 

and test for mercury content

Regional Haze rule cites fine particulates as the primary 

cause of haze and sets a goal of achieving natural background 

visibility in 60 years

Toxics Release Inventory, power plants begin reporting 

releases of mercury, acid gases (SO3, HCI, HF) and other species

1970 1980 1990 2000 2010 2020

Environmental regulation of coal-fired electricity generating plants

is becoming increasingly stringent.
8

Environmental Progress

Overall, air quality levels measured at

thousands of monitoring stations across the

country have shown improvement (i.e. reductions) over the past 20 years for all six

criteria pollutants.

Between 1900 and 1970, emissions of

these six pollutants had increased significantly, with increases of 690% in NOx,

260% in VOCs, and 210% in SO

2. Without

the controls imposed by the 1970 Clean Air

Act and its 1977 and 1990 Amendments,

emissions would have increased at a higher

rate. Since enactment of the CAAA, emissions of the criteria pollutants have decreased

significantly, with the exception of NOx.

Efforts to protect the stratospheric ozone

layer have also been effective. Concentrations of methyl chloroform and chlorofluorocarbons in the upper layers of the

atmosphere have begun to decrease.

Acid Rain Program

Compliance with Title IV of the CAAA

has resulted in significant progress in reducing emissions of SO2 and NOx from U.S.

coal-burning power plants, with major contributions resulting from widespread use of

control technologies developed in the CCT

Program.

SO

2 Emissions Reductions

The CAAA sent a clear signal to industry

in the statement, “SO

2, a primary precursor

to acid rain, must cease to be a major pollutant emission by the beginning of the 21st

century.” Interim response to the regulation

included fuel switching, allowance trading,

and some installation of available emissions

controls. However, to meet the post-2000

cap on SO

2 emissions, high-efficiency control technologies are required.

Prior to the CCT Program, scrubbers capable of high SO2 removal were costly to

build, difficult to maintain, placed a significant

parasitic load on plant output, and produced a

sludge waste requiring extraordinary disposal

measures with considerable land use.

The demonstration projects conducted

under the CCT Program have redefined the

state of the art in scrubber technology. Use

of innovative capture technologies have

nearly halved capital and operating costs,

produced valuable by-products such as wallboard-grade gypsum instead of waste, mitigated plant efficiency losses, and captured

multiple air pollutants.

As a result, advanced FGD systems are

now in operation that provide SO

2 removal

efficiencies of 95-98%. The CCT demonstration projects involving SO2 scrubbers

predated the Title IV Phase 1 compliance

date by two to three years. In 1995, the first

year of compliance under Title IV, SO

2

emissions dropped dramatically, by 3 million tons. Over the first four years of the

CCT Program, SO

2 emissions from the 263

continued on page 10
9

NOx Reduction Technologies

NOx reduction technologies can be grouped

into two broad categories: combustion modifications and post-combustion processes. Some

of the more important NOx control technologies are briefly discussed below.

Combustion Modification

Low-NOx Burners — LNBs are designed to

control the mixing of fuel and air to achieve

what amounts to staged combustion. This results in a lower maximum flame temperature

and a reduced oxygen concentration during

some phases of combustion. This results in

both lower thermal NOx and lower fuel NOx

production.

Overfire Air— OFA is air that is injected into

the furnace above the normal combustion zone.

OFA is generally used in conjunction with operating the burners at a lower than normal air-tofuel ratio, which reduces NOx formation. The

OFA completes the combustion at a lower temperature. OFA is frequently used in conjunction

with LNBs.

Reburning— With reburning, part of the

boiler fuel input (typically 10-25%) is added in

a separate reburn zone. In this zone, the fuelrich reducing conditions lead to the reduction

of NOx formed in the normal combustion zone.

OFA is injected above the reburn zone to complete combustion. Thus, with reburn there are

three zones in the furnace: (1) a combustion

zone with an approximately normal air-to-fuel

ratio; (2) a reburn zone, where added fuel results in a fuel-rich condition; and (3) a burnout

zone, where OFA leads to completion of combustion. Coal, oil, or gas can be used as the

reburn fuel.

Flue Gas Recirculation— FGR, in which

part of the flue gas is recirculated to the furnace, can be used to modify conditions in the

combustion zone (lowering the temperature

and reducing the oxygen concentration) to reduce NOx formation. Another use for FGR is

as a carrier to inject fuel into a reburn zone to

increase penetration and mixing.

Operational Modifications— These modifications involve changing certain boiler operational parameters to create conditions in

the furnace that will lower NOx production.

Examples are burners-out-of-service

(BOOS), low excess air (LEA), and biased

firing (BF). In BOOS, selected burners are

removed from service by stopping fuel flow,

but air flow is maintained to create staged

combustion in the furnace. LEA involves

operating at the lowest possible excess air

level without interfering with good combustion, and BF involves injecting more fuel to

some burners (typically the lower burners)

while reducing fuel to other burners (typically the upper burners) to create staged

combustion conditions in the furnace.

Post-Combustion Treatment

Selective Catalytic Reduction — In SCR,

a catalyst vessel is installed downstream of

the furnace. Ammonia (NH3) is injected into

the flue gas before it passes over the fixedbed catalyst. The catalyst promotes a reaction between NOx and NH3 to form nitrogen

and water vapor. NOx reductions as high as

90% are achievable, but careful design and

operation, such as control of the reagent

dosage and assuring good mixing, are necessary to keep NH3 emissions (referred to

as NH3 slip) to a concentration of a few

ppm.

Selective Noncatalytic Reduction— In

SNCR, a reducing agent (typically NH3 or

urea) is injected into the furnace above the

combustion zone, where it reacts with NOx

as in the case of SCR. Critical factors in applying SNCR are sufficient residence time

in the appropriate temperature range and

even distribution and mixing of the reducing

agent across the full furnace cross section.

Hybrid Processes— SNCR and SCR can

be used in conjunction with each other with

some synergistic benefits. Also, either process can be used in conjunction with LNBs.
10

largest, highest emitting utility plants were

about 5 million tons below their 1980 levels.

The overall reduction in SO2 emissions between 1990 and 1999 was 21%.

These reductions in emissions have occurred where they are most needed — in

some of the highest emitting areas of the

country. For example, affected power plants

in Ohio and Indiana reduced SO2 emissions

by about 44% and 50%, respectively. Moreover, this decrease supports an economic

premise of the Acid Rain Program. Utilities

have more incentive to make substantial

emissions reductions at the highest emitting

plants because they can achieve them at a

lower cost per ton. Concerns that the largest

emitters of SO2 would simply buy allowances and continue to emit at their historical

levels have proved unwarranted thus far.

NOx Emissions Reductions

Prior to the CCT Program, NOx control

technology proven in U.S. utility service

was essentially nonexistent. Today that situation has changed dramatically. The CCT

Program has met the regulatory challenge

by developing and incorporating emerging

NOx control technologies into a portfolio of

cost-effective compliance options for the

full range of boiler types being used commercially.

Products of the CCT Program for NOx

control include:

• Low-NOx burners (LNBs), overfire

air (OFA), and reburning systems that

modify the combustion process to limit

NOx formation.

• Selective catalytic and non-catalytic

reduction technologies (SCR and

SNCR) that remove NOx already

formed.

• Artificial intelligence-based control

systems that effectively handle numerous dynamic parameters to optimize

operational and environmental performance of boilers.

As a result, over three quarters of U.S.

coal-fired generation plants have installed

LNBs. Reburning and artificial intelligence

systems have made significant market penetration as well. All sites that developed

these NOx control technologies have retained them for commercial use. In addition,

numerous commercial installations of SCR

and, to some extent SNCR, are planned or

are under construction to meet the May 1,

2003, target date for implementation of Title

I NOx control requirements.

While overall NOx emissions have remained relatively constant at about 23 million tons/yr since the 1980s, the average

emissions rate (in terms of lb NOx/million

Btu) for power plants participating in Title

IV has decreased by 42% since 1996. Power

plants generate about 30% of total NOx

emissions, with motor vehicles and other

industrial sources contributing most of the

remainder. Although cleaner technologies

are now being used in power plants, the total

amount of electricity generated has increased

significantly, as has the number of vehiclemiles traveled per year.

The IGCC demonstration projects have

achieved excellent environmental performance, with emissions as low as 0.02 lb/

million Btu for SO2 and 0.08 lb/million Btu

for NOx.

Other Emissions Reductions

During the 1990-1999 time period, U.S.

emissions reductions have been 7% for CO,

23% for Pb, 15% for VOCs, and 16% for

PM10. CO and Pb emissions are almost

entirely associated with automotive exhaust.

Between 1970 and 1999, total emissions of

the six principal pollutants decreased 31%.

While this result can be attributed only in

part to the implementation of technologies

developed in the CCT Program, it is worthy

of noting that substantial progress has been

made.

Air Quality Improvements

The emissions reductions cited above are

contributing to measurably improved air

quality. Data collected for the past 10 years

show that ambient SO2 concentrations also

are declining, as are ambient sulfate concentrations. Sulfates are compounds formed

from SO2 emissions and are capable of being transported long distances. They are fine

particulates that aggravate respiratory health

problems, can lead to premature mortality,

and degrade visibility, resulting in a hazy

view of the horizon.

Long-term trends in annual mean aerosol

sulfate concentrations show significant decreases at upwind locations in the U.S. Midwest and at two downwind rural locations in

New York State. During the period from

1978 through 1996, sulfates declined sharply,

continued on page 12
11

Integrated Gasification Combined-Cycle (IGCC)

chemicals, to meet future market requirements.

IGCC technology is applicable to both domestic

and international baseload and repowering applications. Industrial markets also include the production

of environmentally superior transportation fuels,

premium chemicals, and commodity products.

IGCC systems are also very effective in converting

hazardous industrial wastes into valuable, benign

products.

By converting carbonaceous feedstocks, such

as coal and biomass, to high-value and commodity products as well as to baseload power, IGCC

can meet diverse national and international energy

market needs. Coproduction of energy products

maximizes return on investment in these facilities

while minimizing waste and environmental impact.

Thanks to investments in energy R&D by the Federal Government and industry partners, U.S.-

based companies are well-positioned to apply

IGCC systems at home and to capture a healthy

share of what promises to be a multi-billion-dollar

export market for clean power generation technologies.

IGCC technology consists of four basic steps: (1) fuel

gas is generated from coal reacting with high-temperature steam and an oxidant (oxygen or air) in a reducing

atmosphere; (2) the fuel gas is either passed directly to

a hot-gas cleanup system to remove particulates, sulfur,

and nitrogen compounds, or first cooled to produce

steam and then cleaned conventionally; (3) the clean fuel

gas is combusted in a gas turbine generator to produce

electricity; and (4) the residual heat in the hot exhaust

gas from the gas turbine is recovered in a heat-recovery

steam generator. The steam is used to produce additional electricity in a steam turbine generator.

IGCC systems are among the cleanest and most efficient of the emerging clean coal power production technologies. Sulfur, nitrogen compounds, and particulates

are removed before the fuel is burned in the gas turbine,

that is, before combustion air is added. For this reason,

there is a much lower volume of gas to be treated than in

a postcombustion scrubber. The chemical composition of

the gas requires that the gas stream be cleaned to a high

degree, not only to achieve low emissions, but to protect

downstream components, such as the gas turbine, from

erosion and corrosion.

In the gasifier, the sulfur in the coal is released in the

form of hydrogen sulfide (H2S) rather than as SO2. In

some IGCC systems, much of the sulfur-containing gas

is captured by a sorbent injected into the gasifier. Others

use proven commercial H2S removal processes, which

remove up to 99+ % of the sulfur. By-products include

salable sulfur or sulfuric acid.

High levels of nitrogen removal are also possible.

Some of the coal’s nitrogen is converted to NH3, which

can be almost totally removed by commercially available

chemical processes. NOx formed in the gas turbine can

be held to well within allowable levels by staged combustion or by adding moisture to control flame temperature.

IGCC provides industry with highly efficient options for

meeting a wide spectrum of market applications. Gasification technology can process all carbonaceous feedstocks, including coal, petroleum coke, residual oil,

biomass, and municipal and hazardous wastes. It is the

only advanced technology capable of coproducing electric power and a wide variety of commodity and premium

products, such as ultra-clean transportation fuels and
12

Environmental Concerns

are the Driving Force

The environmental drivers influencing the operation

of existing coal-fired power plants over the next decade

are being defined today. Key environmental regulations

have been proposed or promulgated, thus establishing

a need for new compliance technology. These environmental factors include but are not limited to the

following:

• Revised NAAQS for fine particulate matter and ozone.

• Instructions to revise State Implementation Plans to

address ozone concerns in the eastern United States.

• Petitions by northeastern states for the EPA to require

upwind states to reduce NOx emissions from power

plants.

• Requirements for states to address regional haze.

• Proposals to regulate mercury emissions from power

plants.

The cost to comply with these regulations is expected

to be several billion dollars per year; the research challenge is to find improved technologies that dramatically

reduce these costs and fill technology gaps.

Tampa Electric’s Polk

Power Plant, uses 1500 acres

of its site to enhance the environment by the creation of public fishing lakes

for the Florida Fish and Game Commission.

This IGCC power plant uses makeup water

from on-site wells and all process water is

recycled.

with air quality improving by 30% at one of the downwind

locations and 47% at the other. Correspondingly, field data on

sulfate deposition show declines of up to 30% in the U.S.

Northeast and Mid-Atlantic regions. As anticipated, no statistically significant regional trends have been measured for

nitrate concentration levels.

Additional Environmental Effects

In the period before the CAAA, acidification of lakes and

streams, believed to be a direct consequence of acid rain, had

a serious impact on the survival of fish and other aquatic

species. Many streams were reported to have suffered substantial losses of sensitive fish species. The loss of fish occurred

primarily in surface waters resting atop shallow soils that were

not able to buffer, or counteract, acidity. This situation existed

most commonly in the Northeast and Mid-Atlantic, especially

in the Adirondack Mountains in New York State.

Subsequent to the CAAA, many acidic surface waters have

shown declines in sulfate concentrations consistent with objectives of the Acid Rain Program’s emissions reduction.

However, further reductions are needed before soil buffering

capacity is restored.

The pollutants associated with acid deposition also are

believed to reduce visibility. Visibility impairment, or haze,

occurs when particles and gases in the atmosphere, including

sulfates and nitrates, scatter and absorb light. Sulfate particles

account for more than 50% of the impaired visibility, particularly in combination with high summertime humidity. In the

U.S. West, nitrogen and carbon compounds also impair visibility, and sulfur oxides have been implicated as a major

cause of haze in many national parks. However,

some improvement has been achieved as

a result of the Acid Rain Program, but

further progress is needed if pristine conditions are to be fully

restored in these areas.

It has been reported that acid

deposition, combined with other

pollutant and natural stress factors, can damage forest ecosystems, sometimes contributing to the

death of certain tree species. The Acid Rain

Program appears to be reversing some of these

trends. However, the Adirondacks continue to present a challenge. Despite declining emissions and even declining surface

water sulfate concentrations, lakes in this region are not

showing any measurable increase in buffering capacity.

This can be attributed to a number of causes that are not fully
13

understood. Recent research and modeling

efforts suggest that, although conditions

would likely have been substantially worse

without the Acid Rain Program, full recovery of the Adirondacks ecosystems may require further reductions in SO2 and NOx

emissions.

The fine particles of sulfates and nitrates

in the atmosphere are believed to cause

serious health effects as well. Although both

fine and coarse particles are of concern, fine

particles are particularly important because

they easily penetrate the deepest portions of

the lungs. Exposure to these particles has

been implicated in a variety of cardiac- and

respiratory-related problems. The significant reductions in fine particulate emissions

since implementation of the CAAA, especially from coal-burning power plants, have

been estimated to result in substantial health

benefits representing major cost savings.

Sulfur oxides, sulfates, and, to a lesser

degree, nitrates are corrosive to most materials, and thus can severely damage manmade objects exposed to the atmosphere.

Acid deposition degrades materials beyond

natural weathering. The Eastern United

States, with its high concentration of historic

buildings and outdoor monuments, also has

some of the highest levels of acid deposition

in the nation. Materials potentially damaged

also include bridges, buildings, and automotive finishes. Ultimately, cultural preservation, as well as monetary benefits, should

accompany reductions in acid rain emissions, but these effects have not yet been

quantified.

Emissions of air toxics have decreased

somewhat since enactment of the CAAA,

but programs to monitor these emissions

and establish control targets have only recently been put in place.
14

“There is no better example of

America’s energy strength than

in our abundant coal reserves”

. . . Energy Secretary Spencer Abraham

CCT Participant Comments

One measure of the success of the

CCT Program is the number of favorable comments provided by industrial

Participants in the Program. Sample

responses are as follows:

• “Our experience with the Clean

Coal Program allowed us to make

informed decisions on how to best

control NOx emissions throughout

our ... service area. It has saved our

customers millions of dollars.” —

Randall Rush, Southern Company

Services

• “We view our Clean Coal technology project as a natural solution.

Our customers will benefit from a

reliable, economical fuel. Our environment will benefit from superior

emissions reduction performance.

And our company will benefit by

producing reliable generation in a

way that more than meets the Clean

Air Act.” — Girard F. Anderson,

President, Tampa Electric Company

ments demonstrated in the CCT Program

coupled with improvements generated

through competitive forces in the industry.

Peter Tsirigotis, Chief of the Program

Development Branch in EPA’s Clean Air

Markets Division, states that “Some CCT

projects have helped to advance technology before there was a regulatory driver

for the reductions that such a technology

could achieve. This provides an incentive

for industry to begin making technical

innovations earlier than they otherwise

would have. We can see this in the work

that NETL has done on NOx controls in

the past and I think we are seeing it in the

work that NETL is doing on multi-pollutant controls today.”

EPA Comments

Paul Stolpman, Director of the Office

of Atmospheric Programs in EPA’s Office of Air and Radiation, says, “ In the

late 70’s one could see the effects of

acidity in the Northeast, particularly in

the Adirondacks. It was related to emissions of sulfur, three-fourths of which

came from burning coal and oil in our

power plants. But over the past ten years,

the emissions of sulfur from power plants

have greatly dropped ... The Acid Rain

Program cost only about one-third of

what we thought it would in 1990.” This

significant savings has been due in part

to the greatly reduced cost of FGD technologies, largely as a result of developcontinued on page 16
15

Benefits to the Nation of DOE’s Coal Technology Programs

Economic security

A major benefit of near- and mid-term power technologies is low-cost electricity for all

users. Because electricity expense is a major factor in the cost of providing goods and

services, sustaining low electricity production costs is critical for U.S. industry’s competitiveness in the world market. Energy technology provides the foundation for competitive

alternatives needed to meet varying marketplace situations. The United States will also

realize economic benefits from exporting clean energy technologies resulting from DOE

programs. International opportunities for advanced fossil energy technology exports are

enormous.

Reduced balance-of-trade deficit

Because U.S. industry is de-emphasizing longer term research as part of short-term

survival strategies, Federally sponsored technology development is critical to sustaining

U.S. industry’s competitiveness in the world marketplace.

Energy security

Providing technologies that use our abundant indigenous resources as a significant component of our nation’s fuel mix is critical to achieving energy independence and security.

Environmental acceptability

Advanced technologies for improved plant performance and environmental compliance

will yield benefits to human health as well as to the environment. Technologies developed

under the CCT Program offer the means to produce energy from abundant, low-cost fossil fuels without detriment to the environment.

Lower CO2 emissions

With their high-efficiency energy conversion, advanced power generation technologies

will greatly reduce the release of CO2 into the atmosphere as they replace less efficient

technologies.

Continued value of investments. The existing infrastructure at older fossil-energy

power plants will be maintained using repowering and cofiring technologies, thus reducing

the need for investment in new facilities.
16

DOE’s Continuing Role

in Environmental Issues

DOE is committed to developing technologies for reducing pollutants from coalburning power plants through cost-shared

collaboration between government and industry. The intent has been to achieve this

goal quickly enough to allow for demonstration and deployment of new technologies

prior to regulatory deadlines. Some of these

regulations have already been promulgated.

For example, instructions to revise SIPs to

address ozone concerns will require many

Eastern U.S. coal-fired power plants to significantly reduce NOx emissions (to 0.15 lb/

million Btu) by 2003. Power generators are

already ordering hardware for compliance.

On the other hand, many plants are not

subject to these regulations, but may need

similar reductions to meet future regional

haze or PM2.5 standards likely to be enacted

in the 2007 to 2015 time frame. Because

most of these regulations on the horizon are

not yet finalized, and because the implementation dates for some regulations have not

yet been clearly articulated, judgment must

be used in estimating the effectiveness and

timing of needed technologies.

Objectives being pursued by DOE are:

• Develop and demonstrate extremely

low NOx burner technologies (augmented by advanced computer-based

controls).

• Refine post-combustion NOx reduction technologies, such as SCR, to

reduce compliance costs.

• Foster the commercialization of gasification-based processes that convert low-cost carbonaceous

feedstocks to electricity, steam, fuels, chemicals, or hydrogen.

• Develop and demonstrate technologies to address mercury emissions.

• Develop a database in partnership

with other public- and private-sector

organizations on the sources and receptors of ambient fine particulate

matter.

continued on page 18
17

Emissions Standards

History

The Clean Air Act of 1970 established a major air regulatory role for the

Federal Government. The act was further extended by amendments in 1977

and, most recently, in 1990. The 1990

CAAA is one of the most complex and

comprehensive pieces of environmental

legislation ever written. It authorized

EPA to establish standards for a number of atmospheric pollutants, including

SO2 and NOx. Two major portions of

the CAAA relevant to SO2 and NOx

control are Title I and Title IV.

Title I

Title I establishes National Ambient

Air Quality Standards (NAAQS) for six

criteria pollutants, including SO2, NOx,

and ozone (O3). The NAAQS for ozone

is 0.08 ppm (8-hour average), and the

NAAQS for SO2 is 0.14 ppm (24-hour

average).

NOx and volatile organic compounds

(VOCs) in the atmosphere react in the

presence of sunlight to form groundlevel O3, which is a major ingredient of

smog. Many urban areas do not meet

the O3 standard and are classified as

nonattainment. A large number of power

plants are situated within these nonattainment areas. This nonattainment

status is attributable not only to NOx

emissions in a given locality but also to

significant amounts of NOx and VOCs

transported by winds over a wide geographical region.

To address regional pollutant transport, EPA issued a rule governing NOx

emissions from electric power plants

and other large stationary boilers in 22

U.S. Eastern and Midwestern states

and the District of Columbia. EPA’s rule

sets statewide NOx emissions budgets,

which include budget components for

the electric power industry and certain

industrial stationary sources. These

sources are expected to make large

NOx emissions reductions to decrease

transport of pollutants from one region

of the country to another. Federal NOx

emissions limits for utility boilers are

specified at 0.15 lb/million Btu. States

must develop State Implementation

Plans (SIPs) for NOx to achieve the

required statewide emissions budgets.

Title IV - The Acid Rain Program

The overall goal of the Acid Rain

Program is to achieve environmental

and public health benefits through reductions in emissions of SO2 and NOx.

Both the NOx and SO2 control programs use a two-phase approach to

achieve compliance.

For NOx control, Title IV focuses

on a particular set of NOx emitting

sources— coal-fired electric utility

plants. Phase I, begun in 1996, has

reduced NOx emissions in the United

States by over 400,000 tons/year.

These reductions were achieved by

installation of low-NOx burner (LNB)

technology on dry-bottom, wall-fired

boilers and tangentially fired boilers

(Group 1). In Phase II, which began

in January 2000, EPA has established

lower emissions limits for Group 1 boilers and established limits for Group 2

boilers. Group 2 boilers include boilers

using cell-burners, cyclone boilers, wetbottom boilers, and other types of coalfired boilers. It is projected that the

more stringent Phase II limits will result

in an additional NOx reduction of

820,000 tons/year.

The regulations allow for emissions

averaging in which the emissions levels

established by EPA are applied to an

entire group of boilers owned or operated by a single company.

A primary goal of the SO2 control

program is the reduction of annual SO2

emissions by 10 million tons below

1980 levels. Phase I, which began in

1995, affects 263 units at 110 mostly

coal-burning electric utility plants located in 21 Eastern and Midwestern

states. An additional 182 units joined

the program as substitution or compensating units, bringing the total of

Phase I affected units to 445. Phase

II, which began in 2000, tightens the

annual emissions limits and also sets

restrictions on smaller plants fired by

coal, oil, and gas. The Title IV, Phase I

SO2 emissions limit is 2.5 lb/million

Btu, which decreases to 1.2 lb/million

Btu in Phase II.

The Acid Rain Program provides

flexibility in achieving compliance

through an allowance trading system

that harnesses the incentives of the

free market to reduce pollution. Each

allowance permits emitting one ton of

SO2. Affected utility units have been

allocated allowances based on their

historic fuel consumption. For each ton

of SO2 discharged in a given year, one

allowance is retired. Allowances may

be bought, sold, or banked, and any

person may acquire allowances and

participate in the trading system. However, regardless of the number of allowances held, a source may not emit

pollutants at levels that would violate

any federal or state standards, including ambient air standards set under

Title I. During Phase II, the CAAA set

a permanent ceiling (or cap) of 8.95

million annual allowances allocated to

utilities. This cap firmly restricts SO2

emissions and ensures that environmental benefits will be achieved and

maintained.
18

Track Record of Environmental Progress

sions of CO2 because of their higher thermal

efficiency.

Some highlights of the CCT Program are

as follows:

• The CCT Program enabled power generators to respond cost-effectively to the first

wave of NOx control requirements and

positioned industry to respond to more

stringent standards in the 21st century.

Today, three-fourths of all U.S. coal-fired

capacity is equipped with LNBs that cost

a fraction of the cost of NOx pollution

controls available in the 1980s.

• The CCT Program has directly contributed to meeting the initial SO2 reduction

requirements defined by the CAAA by

installing advanced technology at affected

plants. The resultant portfolio of technologies redefined the state of the art in

scrubber technology, enabling industries

to respond to the more stringent standards

imposed by the CAAA in 2000.

• The United States has the largest number

of FGD installations in the world. There

are about 260 units having a total capacity

of 85,000 MWe, representing over onefourth of total U.S. coal-fired capacity.

• Substantial reductions in atmospheric

emissions have been achieved through

CCT-supported demonstration projects involving FGD. For the Pure Air on the

Lake project conducted at Bailly Station,

total SO2 removal from 1992 through

2000 exceeded 700,000 tons. At Plant

Yates, use of the CT-121 FGD process has

removed about 80,000 tons of SO2 during

the period from 1993 through 2000. For

the Milliken Station, operation of the

S-H-U FGD process has removed about

260,000 tons of SO2 during the period

from 1995 through 2000.

• Investment in improved FGD systems in

the United States has saved $40 billion in

the last 30 years.

• CCT-sponsored R&D on FGD has turned

The CCT Program has resulted in the

successful development of cost-effective

pollution control technologies applicable

to a wide range of coal-fired boilers. Application of these technologies on a widespread commercial scale has resulted in

significant emissions reductions that are

meeting EPA regulatory targets.

The value of the environmental technologies demonstrated in the CCT Program can be shown by considering the

impact of applying these technologies to

all coal-fired utility boilers in the United

States. In 1997, total emissions for these

boilers were over 12 million tons of SO2

and 6.8 million tons of NOx. Based on the

quality of coal burned, uncontrolled SO2

emissions would have amounted to over 20

million tons.

If CCT-developed technologies were

applied to all U.S. coal-fired boilers at a

demonstrated average efficiency of 90%,

total SO2 emissions could be further reduced by approximately 10 million tons/

year.

The 1997 NOx emissions of about 6.8

million tons are equivalent to a national

NOx emission rate of 0.75 lb/million Btu.

Combustion modification technologies

demonstrated in the CCT Program readily

reduce NOx emissions to as low as 0.30 lb/

million Btu. Even greater reductions are

possible with post-combustion treatment.

If average NOx emissions from all coalfired boilers were reduced to 0.35 lb/million Btu using commercially available

technology, total NOx emissions would be

reduced by an additional 3.6 million tons/

year to approximately 3.2 million tons/

year.

Similar or better reductions are possible

if older, existing coal-fired units were replaced by newer power generation technologies, such as FBC and IGCC, that have

been demonstrated under the CCT Program. IGCC systems also reduce emisCCT Program

Successes

Successful CCT Program demonstration projects are benefiting existing plants as well as next-generation

systems:

• Advanced technologies have dramatically improved the economic

and environmental performance

of FGD systems for SO2 control.

• NOx reduction technologies have

been or are being retrofitted to a

large segment of the nation’s coalfired power generating capacity.

• Two new IGCC power generation

systems now in commercial operation are among the cleanest coalbased power plants in the world.
19

a concept once thought to be too expensive and unreliable into a U.S. technology

sold throughout the world.

• Innovative FGD processes now permit

recovery of large quantities of salable,

wallboard-grade by-product gypsum. This

eliminates the need to store waste gypsum

in sludge ponds as was practiced when

FGD operations first began. At the Bailly

Station, the amount of wallboard recovered annually is sufficient to build nearly

19,000 homes.

• As a result of technological innovations in

the last 30 years, the Nation has cut sulfur

pollutants by more than 40% while at the

same time tripling the use of coal. The cost

of electric power to U.S. consumers remains the lowest of any industrial nation.

• The CCT Program has provided the foundation for powering the 21st century

through successful demonstration of FBC

and IGCC projects on a commercial scale.

These technologies are inherently clean,

producing negligible emissions of SO

2

,

NOx, and particulates.

• Development of innovative, economically

viable FGD technologies has provided

new opportunities for continued use of

high-sulfur U.S. Eastern coal.

• In March 2000, the Ozone Transport Commission and EPA jointly announced that

emissions of NOx in the U.S. Northeast

and Mid-Atlantic states from major stationary sources were less than half the

emissions from the same sources in 1990.

This is a result of the widespread use of

combustion modification technologies,

especially the CCT technologies LNBs

and OFA.

• In response to the requirements of Title I

of the CAAA for more complete removal

of NOx from power plant stack gases,

SCR technology demonstrated under the

CCT Program is achieving increased commercial application. For example, AEP is

investing $175 million for an SCR installation at its 2600-MWe Gavin Station,

PP&L is installing SCR at its 1500-MWe

Montour Station, and Southern Company

has several major SCR projects underway.

• With the availability of appropriate environmental technologies, significant expenditures on pollution control systems

are anticipated. Worldwide sales of hardware and the accompanying engineering

and monitoring services exceeded $26

billion in 2000. Of this total, about $9

billion was spent by the power industry.

During the first decade of the 21st century, U.S. power plants will commit over

$25 billion to FGD systems in new and

existing facilities. Over the next 20 years,

more than $25 billion will be spent for

NOx reduction equipment in the United

States, including combustion modification and post-combustion systems as well

as monitors and other components.

• According to Power magazine, the development of FBC for coal combustion was

“the commercial success story of the decade in the power generation business.”

• The CCT Program has made available a

number of technologies capable of preventing pollution rather than simply removing pollutants from exhaust gases.

These technologies include: (1) the substitution of coal for a substantial portion of

the coke used in blast furnace operation

and (2) the use of cement kiln dust to scrub

SO

2 from cement plant stack gas, thereby

converting a waste material into a marketable product. In the latter CCT project,

savings on tipping fees for waste disposal,

reuse of the waste products and sale of the

by-products not only offset costs but enable the cleanup system to operate at a

profit. In addition, many CCT processes

achieve minimum or zero discharge of

waste water.
20

Bibliography

Topical Report No. 1, “Tidd: The Nation’s

First PFBC Combined-Cycle Demonstration,” U.S. DOE, March 1990.

Topical Report No. 2, “Coolside and LIMB:

Sorbent Injection Demonstrations Nearing

Completion,” U.S. DOE, September 1990.

Topical Report No. 3, “Reduction of NOx

and SO2 Using Gas Reburning, Sorbent Injection, and Integrated Technologies,” U.S.

DOE, September 1993.

Topical Report No. 4, “SO2 Removal Using

Gas Suspension Absorption Technology,”

U.S. DOE, April 1995.

Topical Report No. 5, “Reducing Emissions

of Nitrogen Oxides via Low-NOx Burner

Technologies,” U.S. DOE, September 1996.

Topical Report No. 8, “The Piñon Pine Power

Project,” U.S. DOE, December 1996.

Five Powerplant Awards Presented

to CCT Projects by Power Magazine

• Tidd PFBC Demonstration Project (The Ohio Power

Company) - 1991

• Advanced Flue Gas Desulfurization Demonstration

Project (Pure Air on the Lake, L.P.) - 1993

• Demonstration of Innovative Applications of

Technology for the CT-121 FGD Process (Southern

Company Services, Inc.) - 1994

• Wabash River Coal Gasification Repowering Project

(Cinergy Corporation/PSI Energy Inc.) - 1996

• Tampa Electric Integrated Gasification CombinedCycle Project (Tampa Electric Company) - 1997
21

Topical Report No. 9, “Control of Nitrogen

Oxide Emissions: Selective Catalytic Reduction (SCR),” U.S. DOE, July 1997.

Topical Report No. 11, “Commercial-Scale

Demonstration of the Liquid Phase Methanol (LPMEOHTM) Process,” U.S. DOE, April

1999.

Topical Report No. 12, “Advanced Technologies for the Control of Sulfur Dioxide

Emissions from Coal-Fired Boilers,” U.S.

DOE, June 1999.

Topical Report No.13, “Technologies for

the Combined Control of Sulfur Dioxide

and Nitrogen Oxides Emissions from CoalFired Boilers,” U.S. DOE, May 1999.

Topical Report No. 14, “Reburning Technologies for the Control of Nitrogen Oxides

Emissions from Coal-Fired Boilers,” U.S.

DOE, May 1999.

Topical Report No. 15, “Blast Furnace Granular

Coal Injection System Demonstration Project,”

U.S. DOE, November 1999.

“Progress Report on the EPA Acid Rain Program,” U.S. EPA, November 1999.

“The Investment Pays Off,” U.S. DOE, November 1999.

Topical Report No. 19, “The Tampa Electric

Integrated Gasification Combined-Cycle Project,

An Update,” U.S. DOE, July 2000.

“Latest Findings on National Air Quality: 1999

Status and Trends,” U.S. EPA, August 2000.

Topical Report No. 20, “The Wabash River Coal

Gasification Repowering Project, An Update,”

U.S. DOE, September 2000.

“Clean Coal Technology Demonstration Program

— Program Update,” U.S. DOE, September 2000.

“...These technologies [Clean Coal] are essential

for growing our economy while also ensuring that

environmental improvements, energy security,

public health, and air and water quality are met”

U.S. Senator Robert C. Byrd
22

An Environmental Success Story

Three quarters of the coal-fired capacity in the United States today

uses low-NOx burners developed through DOE programs, significantly

reducing emissions of one of the chief pollutants responsible for smog

and ozone buildup. A portfolio of cost-effective NOx control technologies suitable for the full range of existing boilers is now available.

A number of low-NOx burners are now widely marketed, total sales

of which are about $4 billion. Reburning has also been successfully

demonstrated for NOx reduction. This process breaks down NOx into

environmentally benign gases by using oil, natural gas or finely ground

micronized coal to reburn the residues of coal-firing.

The Generic NOx Control Intelligent System (GNOCISTM) is the latest innovation to lead the way to the zero-NOx plants of the future.

There are over 50 active or planned GNOCISTM installations, representing more than 25,000 MWe of generation capacity. GNOCISTM

has been shown to result in an overall efficiency improvement of 0.5%,

a 3% reduction in unburned carbon content of utility fly ash, and a 15%

reduction in NOx emissions. This efficiency improvement would allow

a typical eastern U.S. power plant rated at 1000 MWe to reduce its

coal consumption by up to 25,000 tons/year.

The costs of reducing NOx emissions by retrofitting power plants

are now up to 90% lower than they would have been without the

Federal Government’s research investment.

Milliken Station is located in

an environmentally sensitive

area on the shores of Cayuga

Lake, one of the famous

Finger Lakes in New York

State.
23

Tackling Global Energy Issues of the 21st Century

Worldwide, the demand for power is increasing exponentially. At the same time,

the energy sectors of many countries are undergoing major transformations. Increasingly stringent environmental regulations, growing international concerns over

global climate change, and increased competition among fuels drive the need for

advanced power technologies that deliver

electricity efficiently, cleanly, and economically. These trends offer great opportunities for clean coal technologies and

advanced power generation systems, the

wide-scale adoption of which would protect

local, regional, and global environments.

Quadrillion Btu/yr.

7.2

18.8

22.1

SO2 NOx PM

4.4

1.4

0.8

1.1

0.58

0.35 0.5

0.03

Successes to date:

Pollutant emissions

per unit of coal burned

have decreased significantly

Challenges for the future:

Increased coal use has brought

pressure to reduce emissions further

Average rate of pollutant emissions

from U.S. coal-fired power plants

Coal use for power

generation in the U.S.

Pollutant Emissions,

lb/million Btu coal burned

5

4

3

2

1

0

20

16

12

8

4

0

1970 1997 2005 (projected)

Since 1970, the environmental performance of U.S. coal-fired

power plants has improved while coal use has increased.
24

The CCT Program

The Clean Coal Technology (CCT) Demonstration

Program, a model of government and industry cooperation, responds to the mission of the Department of

Energy (DOE) to foster the development and implementation of secure and reliable energy systems that are

environmentally and economically sustainable. The

CCT Program represents an investment of over $5 billion in advanced coal-based technology, with industry

and state governments providing a significant share —

66% — of the funding. With 26 of the 38 active projects

having completed operations, the CCT Program has

yielded technologies that are capable of meeting existing and emerging environmental regulations and competing in a deregulated electric power marketplace.

Estimated coal reserves in the United States are 4

trillion tons, of which over 270 billion tons are recoverable using current methods. The CCT Program provides

a portfolio of technologies that will assure that this resource can continue to supply the nation’s energy

needs economically and in an environmentally sound

manner. As the new millennium begins, many of the

clean coal technologies have achieved commercial status. Industry stands ready to respond to the energy and

environmental demands of the 21st century, both domestically and internationally. For existing power plants, there

are cost-effective environmental control devices to control

SO2, NOx, and PM. Also ready are a new generation of

technologies that can produce electricity and other commodities, such as steam and synthesis gas, at high efficiencies consistent with concerns about global climate

change.

The CCT Program has taken a pollution prevention approach as well, demonstrating technologies that produce

clean coal-based solid and liquid fuels by removing pollutants or their precursors. Lastly, new technologies have

been introduced into major coal-using industries, such as

iron making, to enhance environmental performance.

Thanks in part to the CCT Program, coal — abundant,

secure, and economical — can continue in its role as a

key component in the U.S. and world energy markets.
25

To Receive Additional

Information

To be placed on the Department of

Energy’s distribution list for future information on the Clean Coal Technology

Program, the demonstration projects

it is financing, or other Fossil Energy

Programs, please contact:

Robert C. Porter, Director

Office of Communication

U.S. Department of Energy

FE-5

1000 Independence Ave SW

Washington DC 20585

(202) 586-6503

(202) 586-5146 fax

robert.porter@hq.doe.gov

Otis Mills

Public Information Office

U.S. Department of Energy

National Energy Technology Laboratory

P.O. Box 10940

Pittsburgh PA 15236-0940

(412) 386-5890

(412) 386-6195 fax

otis.mills@netl.doe.gov

U.S. Department of Energy

Contacts for CCT Program

C. Lowell Miller

Director, Coal Fuels & Industrial Systems

U.S. Department of Energy

FE-24 Germantown Bldg.

Germantown MD 20874-1290

301-903-9451

301-903-2238 fax

lowell.miller@hq.doe.gov

Thomas A. Sarkus

Director, Coal Power Projects Division

National Energy Technology Laboratory

P.O. Box 10940

Pittsburgh PA 15236-0940

(412) 386-5981

(412) 386-4775 fax

thomas.sarkus@netl.doe.gov

Thomas J. Feeley

Product Manager, Environmental

National Energy Technology Laboratory

P.O. Box 10940

Pittsburgh PA 15236-0940

(412) 386-6134

(412) 386-4822 fax

thomas.feeley@netl.doe.gov

Joseph B. Renk III

Project Manager

National Energy Technology Laboratory

P.O. Box 10940

Pittsburgh PA 15236-0940

(412) 386-6406

(412) 386-4775 fax

joseph.renk@netl.doe.gov

This report is available on the Internet at

U.S. DOE, Office of Fossil Energy’s home

page: www.fe.doe.gov

and on the Clean Coal Technology

Compendium home page:

www.lanl.doe.gov/projects/cctc
26

How NOx Is Formed

in a Boiler

Most of the NOx formed during

the combustion process is the result of two oxidation mechanisms:

(1) reaction of nitrogen in the combustion air with excess oxygen at

elevated temperatures, referred to

as thermal NOx; and (2) oxidation

of nitrogen that is chemically

bound in the coal, referred to as

fuel NOx. For most coal-fired units,

thermal NOx typically represents

about 25% and fuel NOx about

75% of the total NOx formed.

However, for cyclones and other

boilers that operate at very high

temperatures, the ratio of thermal

to fuel NOx is different, and thermal NOx can be considerably

higher than fuel NOx. In addition,

minor amounts of NOx are formed

early in the combustion process

through complex interactions of

molecular nitrogen with hydrocarbon free radicals to form reduced

nitrogen species that are later

oxidized to NOx, referred to as

prompt NOx.

The quantity of thermal NOx

formed depends primarily on the

“three t’s” of combustion: temperature, time, and turbulence.

In other words, flame temperature,

the residence time at temperature,

and the degree of fuel/air mixing,

along with the nitrogen content of

the coal and the quantity of excess

air used for combustion, determine

NOx levels in the flue gas. Combustion modifications manage the

mixing of fuel and air, thereby reducing temperature and initial turbulence, which minimizes NOx

formation.

Thousands of short tons/yr

8,000

6,000

4,000

2,000

1970 1975 1980 1985 1990 1995 1997 1999

20,000

15,000

10,000

5,000

1970 1975 1980 1985 1990 1995 1997 1999

Thousands of short tons/yr

1.20

1.00

0.80

0.40

0.20

5.0

4.0

3.0

2.0

1.0

NOx

SO2 lb/million Btu

lb/million Btu

Average lbs SO2 per million Btu

0.60

Average lbs NOx per million Btu

Emission rates of NOx and SO2 have

decreased significantly since 1970.
27

Fluidized-Bed Combustion (FBC)

In FBC, coal is mixed with a sorbent and combusted with air in a reaction vessel. The incoming

air stream fluidizes the reactor contents. Most of the

SO2 produced by oxidation of the sulfur in the coal

is captured by the sorbent. The resultant waste is a

dry, benign solid that can be disposed of easily or

used in agricultural and construction applications.

At combustion temperatures of 1,400-1,600 °F

(760-870 °C), the fluidized mixing of the fuel and

sorbent enhances both combustion and sulfur capture. The operating temperature range is much

lower than that of a conventional pulverized-coal

boiler and below the temperature at which thermal

NOx is formed. In fact, FBC NOx emissions are

about 70-80% lower than those for uncontrolled

conventional pulverized-coal boilers. Thus, FBCs

substantially reduce both SO2 and NOx emissions.

They also have the capability of using high-ash

coal, whereas conventional pulverized-coal units

must limit ash content in the coal to lower levels.

Two parallel paths have been pursued in FBC

development — bubbling and circulating beds.

Bubbling beds use a dense fluid bed and low fluidization velocity to effect good heat transfer and

mitigate erosion of an in-bed heat exchanger.

Circulating beds use a relatively high fluidization

velocity, which entrains the bed material, usually in

conjunction with hot cyclones to separate and recirculate the bed material from the flue gas before it

passes to a heat exchanger. Hybrid systems have

also evolved from these two basic approaches.

FBCs can be either atmospheric (AFBC) or pressurized (PFBC). AFBC operates at atmospheric

pressure while PFBC operates at pressure 6-16

times higher. PFBC offers potentially higher efficiency and, consequently, reduced operating costs

relative to AFBC, as well as smaller size per unit of

power output. Second-generation PFBC integrates

the combustor with a pyrolyzer (coal gasifier) to fuel

a gas turbine (topping cycle), the waste heat from

which is used to generate steam for a steam turbine

(bottoming cycle). The inherent efficiency of the gas

turbine and waste heat recovery in this combinedcycle mode significantly increase overall efficiency.

Such advanced PFBC systems have the potential

for thermal efficiencies over 50%.

1985 1990 1995 1997

Average Cost of Electricity,

cents/kWh

10

8

7

6

2

5

4

3

9

1

0

Coal Use, Quadrillion Btu per year

20

18

15

13

10

8

5

3

0

cents/kWh

Since 1985, coal use has increased while

the cost of electricity has gone down.
28

List of Acronyms and Abbreviations

Btu ......................................................................................................... British thermal unit

CAAA ......................................................................... Clean Air Act Amendments of 1990

CCT .................................................................................................Clean Coal Technology

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

CT-121.................................................... Chiyoda Corporation Thoroughbred-121 Process

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

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

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

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

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

FGR ..................................................................................................... flue gas recirculation

GHG ............................................................................................................. greenhouse gas

GNOCISTM .......................................................... Generic NOx Control Intelligent System

HAPs .............................................................................................. hazardous air pollutants

H2S ............................................................................................................. hydrogen sulfide

IGCC ...................................................................... integrated gasification combined-cycle

LNBs ......................................................................................................... low-NOx burners

MWe ........................................................................................ megawatts of electric power

NAAQS ............................................................... National Ambient Air Quality Standards

NETL ................................................................... National Energy Technology Laboratory

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

NOx .............................................................................................................. nitrogen oxides

NSPS ...........................................................................New Source Performance Standards

OFA ..................................................................................................................... overfire air

PM .............................................................................................................particulate matter

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

S-H-U ................................................................................ Saarberg-Holter-Umwelttechnik

SIP .............................................................................................. State Implementation Plan

SNCR.................................................................................. selective noncatalytic reduction

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

SO3 ................................................................................................................. sulfur trioxide

μ ...................................................................................... micron (one-millionth of a meter)

VOCs ........................................................................................ volatile organic compounds