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
0
200
400
600
800
1000
1200
Co
al,
sub
crit
ica
l
Co
al,
sup
erc
riti
cal
Co
al,
IGC
C
Na
tura
l Ga
s
So
lar
PV
Ge
oth
erm
al
So
lar
CS
P
Bio
ma
ss
Win
d
12 18 22 45 48
469
838863
1060
All types of coal plants still emit more CO
2 than any
other electricity source.
Gra
ms
of
carb
on
dio
xid
e e
qu
iva
len
t p
er
kilo
wa
tt-h
ou
r
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
llutio
n C
on
trols
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.
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