Dirty coal is desperately trying to clean up its image. Coal proponents

are trying to buy their way into a clean energy future by promoting

“high efficiency, low emissions” coal plants. The coal industry has even

attempted to extract funding from climate finance mechanisms, such as the

Clean Development Mechanism, for more efficient coal plants.

It is time to stop this deception.

Coal-fired power plants produce the dirtiest electricity on the planet. They

poison our air and water and emit far more carbon pollution than any other

electricity source. While pollution control equipment can reduce toxic air

emissions, they do not eliminate all of the pollution. Instead, they transfer

much of the toxic air pollutants to liquid and solid waste streams.

Often, companies and governments prioritise profits over public health and

choose not to install the full suite of available pollution control equipment.

In these cases, toxic pollution still goes into the air, leading to premature

deaths and increased rates of disease.

Coal plants are responsible for 72% of electricity-related greenhouse gas

emissions. Even the most efficient coal plants generate twice as much

carbon pollution as gas-fired power plants and over 20-80 times more

than renewable energy systems.1,2 Technology to capture and store carbon

dioxide is expensive and largely unproven.

Moreover, if you consider the social and environmental costs of coal mining,

preparation and transport, coal generation can never be considered “clean.”

This factsheet describes the technologies used to control pollution and

improve the efficiencies of coal plants.

“Clean Coal” is a Dirty LieCoal fired power station Hunter Valley, NSW. Credit: Greenpeace/Sewell

COAL FACTSHEET #4

Lifetime Impacts of a Typical 550-MW Supercritical Coal Plant with Pollution Controls• 150 million tonnes of CO

2

• 470,000 tonnes of methane

• 7800 kg of lead

• 760 kg of mercury

• 54,000 tonnes NOx

• 64,000 tonnes SOx

• 12,000 tonnes particulates

• 4,000 tonnes of CO

• 15,000 kg of N2O

• 440,000 kg NH3

• 24,000 kg of SF6

• withdraws 420 million m3 of

water from mostly freshwater

sources

• consumes 220 million m3

of water

• discharges 206 million m3

of wastewater back into rivers

Source: “Life Cycle Analysis: Supercritical Pulverized Coal (SCPC) Power Plant.” US Department of Energy, National Energy Technology Laboratory, US DOE/NETL-403–110609, September 30, 2010. We assumed a .70 plant capacity factor and a 50-year lifespan.

2 | C O A L F A C T S H E E T # 4

The Dirt on “Clean Coal” Technologies

For decades, the coal industry has used the term “clean

coal” to promote its latest technology. Currently, “clean

coal” refers to: 1) plants that burn coal more efficiently;

2) the use of pollution control technologies to capture

particulate matter, sulfur dioxide, nitrous oxides and other

pollutants; and/or 3) technologies to capture carbon dioxide

emissions, known as carbon capture and storage (CCS).

1) IMPROVING EFFICIENCYThe coal industry is promoting the construction of “high

efficiency” plants, which generate more electricity per

kilogram of coal burned. Today, nearly 75% of operating

coal plants are considered subcritical, with plant

efficiencies between 33 and 37% (i.e. between 33% and

37% of the energy in the coal is converted into electricity).

• Supercritical plants, which produce steam at pressures

above the critical pressure of water, can achieve

efficiencies of 42-43%. This “new” technology was first

introduced into commercial service in the 1970s. India

and China have issued national directives to employ

supercritical technology in all new coal plants to reduce

fuel costs.

• Ultra-supercritical (USC) plants can achieve efficiencies

of up to 45% through the use of higher temperature

and pressure.

• Integrated gasification combined cycle (IGCC) plants

can supposedly achieve efficiencies of up to 50%. In

an IGCC plant, coal gas is used in a combined cycle

gas turbine to reduce heat loss. Few IGCC plants have

been constructed because of their higher capital and

operating costs and more complex technical design.3

• Circulating fluidised bed combustion (CFBC) power

plants burn coal with air in a circulating bed of limestone.

This reduces sulphur dioxide emissions but not

emissions of other pollutants. CFBC is advantageous

because it can burn a variety of fuels, but they are less

efficient than other coal plants.

Supercritical plants reduce CO2 emissions by only 15-20%

compared to subcritical plants. As a result, they still emit

far more CO2 and hazardous pollutants than any other

electricity generation source. In addition, their higher

construction costs have deterred many poorer nations

from adopting these technologies. In 2011, half of all new

coal plants were built with subcritical technology.

2) AIR POLLUTION CONTROL TECHNOLOGIESAir pollution control technologies can control the release

of many hazardous pollutants into the atmosphere.

However, after these pollutants are captured, they are

often stored in unlined waste ponds or ash dumps.

They can then leach into surface and ground water,

contaminating water supplies on which people and

wildlife depend. In addition, there are currently no

pollution control technologies to eliminate ultra hazardous

pollutants, such as dioxins and furans.

Air pollution controls are expensive, adding hundreds of

millions of dollars to the cost of a coal plant. They can

raise the cost of generation to around 9 US cents per

kilowatt-hour. Pollution controls reduce the efficiency of

coal plants, requiring more coal to be burned per unit of

electricity generated. Project developers often do not

install all available pollution controls to cut costs. Coal

operators sometimes shut off existing pollution controls

to reduce operating costs. In these cases, corporate

profits come at the expense of public health and the

environment.

The following section describes common air pollutants

from coal-fired power plants and technologies used to

control them.

THE CARBON INTENSITY OF ELECTRICITY GENERATION

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Source: IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation, Annex II: Methodology, 2011; Whitaker, M. et al (2012). “Life Cycle Greenhouse Gas Emissions of Coal-Fired Electricity Generation.” Journal of Industrial Ecology, 16: S53–S72.

E N D C O A L | 3

Fine Particulates (PM2.5)

Exposure to fine particulates (less than 1/30th the width

of a human hair) increases rates of heart attack, stroke

and respiratory disease. Fabric filters, or baghouses, are

often used to control the direct emission of particulates.

Baghouses can capture 99.9% of total particulates and 99.0-

99.8% of fine particulates. For a typical 600-MW coal plant,

this system costs about $100 million. If one or two of the

bags break, emissions of particulates can increase 20-fold.

Electrostatic precipitators (ESP) can also be used to

capture particulates. An ESP can capture over 99% of

total particulates and 80-95% of fine particulates. The best

controls include both fabric filters and ESP to achieve even

higher removal of particulates.

While these systems capture the direct emissions of fine

particulates, they do not capture fine particulates which

form in the atmosphere through the reaction of nitrogen

oxides and sulphur dioxide. These fine particulates are of

particular concern to public health.

Sulphur Dioxide

Sulphur dioxide emissions can cause acid rain and lead

to the formation of fine particulates, which increase

cancer and respiratory disease. Two methods to reduce

sulphur emissions are switching to low-sulphur coal

and capturing emissions after combustion. The primary

method of controlling sulphur dioxide emissions is flue gas

desulphurisation, also known as scrubbing or FGD. FGD

may use wet, spray-dry or dry scrubbers.

In the wet scrubber process, exhaust gases are sprayed

with vast amounts of water and lime. The International

Energy Agency (IEA) estimates that wet scrubbers may use

up to 50 tonnes of water per hour. This process generates

a huge slurry of sulphur, mercury and other metals which

must be stored in waste ponds indefinitely. If the dams

that impound the slurry ponds break, millions of litres

of waste can spill into rivers, causing large fish kills and

contaminating drinking and irrigation supplies with heavy

metals and other toxics. Modern scrubbers typically remove

over 95% of SO2 and can achieve capture rates of 98-99%.

Dry scrubber processes are used at some coal plants. In

this process, lime and a smaller amount of water are used

to absorb sulphur and other pollutants. This waste is then

collected using baghouses or electrostatic precipitators.

Modern systems can capture 90% or more of SO2.

FGD is the single most expensive pollution control device

and can cost $300-500 million for a 600-MW plant. This

can amount to roughly 25% of the cost of a new coal plant.

Many new plants do not install FGDs because of their cost.

Nitrogen Oxides

The emissions of nitrogen oxides can lead to the

formation of fine particulates and ozone. These pollutants

can increase rates of respiratory disease, including

Baghouse (PM) $100 million

Selective Catalytic Reduction (N0

x) $300 million

Scrubbers (S02) $400 million

THE MOUNTING COSTS OF A 600-MW COAL PLANT

Activated Carbon Injection (Mercury) $3 million

Ultrasupercritical Technology$95 million additional

Supercritical Technology$130 million additional

Subcritical Technology$770 million

Total Cost = $1.8 billion

Note: C02 emissions are unabated.

Source: IEA Technology Roadmap (March 2013);NESCAUM (2011)

Po

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4 | C O A L F A C T S H E E T # 4

emphysema and bronchitis. Technologies such as low

NOx burners, which use lower combustion temperatures,

can be used to reduce the formation of NOx. After

combustion, selective catalytic reduction (SCR) can be

used to capture NOx pollution. Using a combination of

NOx reduction techniques, emissions can be reduced by

90%. SCR technology costs about $300 million per unit. An

alternative – selective non-catalytic reduction – is cheaper

and can achieve 60-80% control efficiency.

Mercury

Coal burning is the single largest human-caused source

of mercury emissions. Mercury is a neurotoxin, which can

cause birth defects and irreversibly harm the development

of children’s brains. In 2013, 140 nations ratified the UN

Minamata Convention on Mercury and agreed to reduce

their emissions of mercury to the environment.

Mercury emissions can be reduced somewhat by

coal washing, however, this generates mercury-laden

wastewater which can contaminate ground and surface

water. Most mercury emissions can be captured in systems

used to control other pollutants, such as baghouses, SCR

and FGD systems.

A system known as activated carbon injection can also be

used to capture mercury. Together with a baghouse or ESP,

this system can capture up to 90% of mercury emissions

and costs about $3 million for a 600-MW plant.4

3) CARBON CAPTURE AND STORAGE Some coal advocates assert that carbon capture and

storage (CCS) can reduce carbon dioxide emissions

from coal-fired power plants. CCS involves capturing

carbon dioxide emissions, compressing them into a liquid,

transporting them to a site and injecting them into deep

underground rock formations for permanent storage.

CCS is currently an extremely expensive, unproven

technology, which has not been widely implemented on a

commercial scale. The first barrier to CCS is its economic

viability. Between 25-40% more coal is required to

produce the same amount of energy using this technology.

Consequently, more coal is mined, transported, processed

and burned, increasing the amount of air pollution and

hazardous waste generated by coal plants. The cost of

construction of CCS facilities and the “energy penalty”

more than doubles the costs of electricity generation from

coal, making it economically unviable. The highly touted

600-MW Kemper plant in the US is mired in delays and

cost overruns. Originally projected to cost $2.8 billion,

the plant is now estimated to cost $6.1 billion and is three

years behind schedule.

Furthermore, there are considerable questions about the

technical viability of CCS. It is unclear whether CO2 can be

permanently sequestered underground and what seismic

risks underground storage poses. There are also doubts

about whether there are enough suitable underground

storage sites situated close to coal plants to physically

store the captured carbon dioxide.

ENDNOTES

1 “New unabated coal is not compatible with keeping global warming below 2°C”, Statement by leading climate and energy scientists, November 2013, p.3.

2 Benjamin K. Sovacool, “Valuing the Greenhouse Gas Emissions from Nuclear Power: A Critical Survey”, Energy Policy, V. 36, p. 2940 (2008).

3 Technology Roadmap: High-Efficiency, Low-Emissions Coal-Fired Power Generation, OECD/International Energy Agency, Paris, 2012, pg. 24.

4 James E. Staudt, Control Technologies to Reduce Conventional and Hazardous Air Pollutants from Coal-Fired Power Plants, Andover Technology Partners, March 31, 2011. http://www.nescaum.org/documents/coal-control-technology-nescaum-report-20110330.pdf

ENDCOAL.ORG

The Limits of Canada’s Boundary Dam ProjectThe coal industry lauded the recent opening of the

110-MW Boundary Dam project in Saskatchewan,

Canada as a milestone in commercial-scale CCS.

However, the US$1.4 billion project would not have

proceeded without $194 million in government sub-

sidies. (The same amount of money could have built

a 240 MW solar PV plant.)

SaskPower considered several options before even-

tually downsizing the project. Retrofitting CCS to an

existing coal plant would have consumed 40% of the

power generated by the plant. A proposal to build a

new 300-MW coal plant with CCS would have cost

$3.1 billion. In a telling sign, SaskPower admitted that

the project was also downsized because it was not

profitable to generate and capture more than one

million tons of CO2 per year. Typical 600-MW coal

plants emit roughly 3.5 million tons of CO2 per year.

Instead of pouring millions of dollars into troubled

CCS pilot projects, governments should prioritize in-

vestments in renewable energy to sustainably meet

our energy needs.