The Problems with So-called “Clean Coal”
Kelvin S. Rodolfo

It is necessary to make six main points regarding “clean coal”.

A. The term “clean coal” is an oxymoron – like a square circle or a benevolent dictator.
Clean burning of coal simply cannot happen.

Table 1 presents the pollution from combusting a million tons of coal in a typical 500-
megawatt electricity plant1. Note that CO2 is by far our greatest pollutant, a point that we
will expand upon later.

Table1. Pollutants generated by a typical 500 megawatt coal-burning electricity plant1

3,700,000 tons of carbon dioxide (CO2), the primary human cause of global warming--as much carbon
dioxide as cutting down 161 million trees.

10,000 tons of sulfur dioxide (SO2), which causes acid rain that damages forests, lakes, and buildings,
and forms small airborne particles that can penetrate deep into lungs.

500 tons of small airborne particles, which can cause chronic bronchitis, aggravated asthma, and
premature death, as well as haze obstructing visibility.

10,200 tons of nitrogen oxide (NOx), as much as would be emitted by half a million late-model cars.
NOx leads to formation of ozone (smog) which inflames the lungs, burning through lung tissue
making people more susceptible to respiratory illness.

720 tons of carbon monoxide (CO), which causes headaches and place additional stress on people with
heart disease.

220 tons of hydrocarbons, volatile organic compounds (VOC), which form ozone.

170 pounds [77 kg] of mercury where just 1/70th of a teaspoon deposited on a 25-acre [10-hectare]
lake can make the fish unsafe to eat.

225 pounds of arsenic [102 kg], which will cause cancer in one out of 100 people who drink water
containing 50 parts per billion.

114 pounds [52 kg] of lead, 4 pounds [1.8 kg] of cadmium, other toxic heavy metals, and trace
amounts of uranium.

B. Several techniques are either in use, or being tested experimentally, on “cleaning”
coal2. But they do not make the coal really clean.

To reduce emissions, coal washing can chemically remove impurities from the surfaces of
lumps and particles of raw coal. This cleans the coal somewhat and increases its efficiency
as fuel, but lets the noxious substances inside the coal proceed into the furnace. After
combustion, electrostatic precipitators pass the hot flue gasses through an electric field,
removing 99% of the fine particles, which stick to collecting plates. Flue gas desulfurization
removes sulfur emissions after combustion, most commonly by using “wet scrubbers” that
spray water and limestone on the flue gasses streaming out of the furnace. The sulfur fumes
in the hot gas react with the water and limestone. This can produce gypsum used in cement
making and the construction industry, but it is also simply discarded as “fly ash” and stored
in land fills. Desulfurization is claimed to be 99% effective, but adds greatly to the cost.

C. Coal has already been made into liquid fuels like diesel, using “coal-to-liquid” (CTL)
technology2,3,4,5. But this is expensive and ultimately results in making almost twice as
much atmospheric CO2 as does burning diesel distilled from petroleum.

Hitler’s industrialists used the Fischer–Tropsch chemical process to make fuels for his
Panzers, Messerschmitt aircraft and other war machines, replacing every 3 barrels of crude
oil with one ton of good quality coal. The Fischer–Tropsch technology heats the coal up to
350°C and mixes it with water to make a hot gas that can be burned directly to make energy,
or condensed into liquid fuel for automobiles and airplanes. The process is very energy-intensive,
expensive, and uses much water. Naturally, the rising scarcity of oil has made the
Fischer–Tropsch synthesis sound attractive to the automobile-driving public. Some fuels
made that way offer the advantage of burning more cleanly than diesel. To distill diesel from
petroleum is much cheaper, however, so of course synthetic fuel would seriously impact
pocketbooks. The Integrated Gasification Combined Cycle technique converts coal to an
efficiently burnable gas and reduces emissions. IGCC is only experimental.

D. All cleaning methods can remove many of the pollutants, but greatly increase the
costs of the plant and its operation and maintenance. It also cannot change a rigid,
inescapable chemical fact that remarkably few people know: CO2 is humanity’s most
copiously contributed greenhouse gas, and coal is the worst offender. Simple “molar”
chemistry means that burning 12 tonnes of carbon in coal unavoidably produces 44
tonnes of CO2.

Stated more simply, burning any single weight (gram, pound, kilo, ton) of coal makes 3.67
equivalent weights (grams, pounds, kilos, tonnes) of CO2. The following illustration
illustrates what that arithmetic means. - See attached file,

Every carbon atom weighs 12 “atomic mass units” or “amu”; every oxygen atom weighs 16
amu. When a carbon atom is burned, it combines with two oxygen atoms to form a molecule
of CO2 weighing 44 amu.

By the same token, burning any 12 weights of carbon will make 44 of the same weights of
CO2. For example, burning 12 kilos of coal carbon would make 44 kilos of CO2.
More generally, burning any weight of coal carbon would make CO2 weighing 3.7 times
more than that weight.

Twelve kilos of typical bituminous coal with a specific gravity of 1.35 would make 8,900
cubic centimeters, equivalent to a cube 20.7 centimeters on the side. The 44 kilos of CO2
formed by burning it, if frozen into “dry ice” with a specific gravity of 1.56, would have a
volume of 28,200 cubic centimeters, or a cube 30.4 centimeters on the side.

Of course, when we burn coal, we do not make it into solid “dry ice”. We return the CO2
into the air from which Nature took it millions of years ago, thus enhancing greenhouse
global warming. What this figure shows is the fundamental absurdity of the idea behind
carbon dioxide capture and storage.

E. Not only is coal the world’s biggest source of man-made CO2; of all our fossil fuels, it
also yields less electricity for the costs in pollution it inflicts on us and our global
environment. . “…coal generates the most CO2 per unit energy of any fossil fuel …6 It
emits at least 6% more CO2 per unit of power generated than petroleum or natural gas
(Table 2).

Table 2. U.S. carbon dioxide emissions and electric power generation by fuel type.7,8
CO2 emissions, Power generation, Pounds C02 emitted
Fuel type x 1000 cu. meters million KWH per KWH
Coal 17,876,910 1,881,571 2.095
Petroleum 106,294 119,025 1.969
Natural gas 337,004 462,433 1.321

For coal to be truly “clean coal” ultimately means CCS: CO2 capture and
sequestration forever, deep underground or in the ocean. The state of Illinois has huge
reserves of coal, and much of the rhetoric about clean coal is forever repeated in my
Chicago-based ears. But no one in the world has yet demonstrated commercially viable
sequestration.

As it turns out, the first CO2-sequestering plant being built in the U.S., the 275-megawatt
FutureGen plant scheduled to open in 2012 in Matoon, Illinois, was cancelled early this year
by the U.S. Department of Energy, because its construction was far too expensive, costs
skyrocketing to U.S.$ 1.8 billion9.

But let’s say CCS is indeed implemented successfully. According to the IPCC10, 99% of
geo-sequestered CO2 would remain after 1,000 years; and much would stay sequestered for
millions of years. If CO2 is stored in the ocean, 30-85% would remain after 500 years. “Out
of sight, out of mind” may be psychologically comforting, but we cannot foresee what
geological accident such as asteroid impacts in the coming eons might release it. Keep in
mind that a cloud of escaped CO2 replacing the air you breath will kill you quickly and
certainly by denying your body the oxygen it must have. Entire African villages have been
wiped out by CO2 released from volcanic lakes…

Storing CO2 by chemically making it into solid minerals would prevent leakage, but this
would require 60-180% more energy input10. We need to forget about “clean coal”. Burn it,
if you must, and the environment and global warming be damned, but don’t fool yourself
with propaganda and cleansing rhetoric.

Notes

1. Union of Concerned Scientists, 2005, Environmental impacts of coal power: air pollution.
http://www.ucsusa.org/clean_energy/coalvswind/c02c.htm. Formatted as Table 4 in
Rodolfo, 2008.

2. news.bbc.co.uk/1/hi/sci/tech/4468076.stm

3. Washington Post, Page A16, June 18, 2007; Coal-to-Liquid Boondoggle: A risky solution to
America's energy woes. washingtonpost.com/wpdyn/
content/article/2007/03/09/AR2007030902302.html?referrer=email

4. Ledford, Heidi, 7 December 2006, Liquid fuel synthesis: Making it up as you go along.
Nature 444, 677-678.

5. Hargreaves, Steve, 23 April 2007, Crunch time for Hitler's fuel. CNNMoney.com
http://money.cnn.com/2007/04/20/news/economy/coal_liquid/index.htm?postv...
704230. Accessed 25 April 2007.

6. Semeniuk, Ivan, 17 March 2007, Cheap Coal Threat to Global Climate. The New Scientist
http://environment.newscientist.com/channel/earth/mg19325954.700-cheap-c...
global-climate.html

7. Rodolfo. Kelvin S., “Peak Oil”: The global crisis of diminishing petroleum supply,
and its implications for the Philippines. Version of a forthcoming manuscript in the
Journal of Asian Studies.

9. Data from U.S. Environmental Protection Agency, July 2000, “Carbon Dioxide Emissions
from the Generation of Electric Power in the United States”.

9. Nature, 7 February 2008, “Carbon burial buried.” V 451, p 612-613.

10. Intergovernmental Panel on Climate Change, Working Group III, 22-24 September 2005,
Carbon Dioxide Capture and Storage, Summary for Policymakers.

Kelvin S. Rodolfo
Professor Emeritus
University of Illinois at Chicago
and
Adjunct Professor
National Institute of Geological Sciences
University of the Philippines
20 March 2008
Viroqua, Wisconsin

Biographical note

Kelvin Rodolfo is concurrently Professor Emeritus with the Department of Earth &
Environmental Sciences, University of Illinois at Chicago, and Adjunct Professor with the
National Institute of Geological Sciences, University of the Philippines – Diliman. In
January and February 2008 he was a DOST Balik Scientist.

After graduating from UP Diliman in 1958, he worked for two years as a petroleum
exploration geologist in Luzon, Cebu and Mindanao, and has been an interested observer of
the petroleum industry ever since.

He earned his Master of Science and PhD degrees at the University of Southern California
from 1960 to 1967, and rose from Instructor to Professor at the University of Illinois at
Chicago.

At UIC he won 6 Awards for Excellence in Teaching. His research, funded by 13 U.S.
National Science Foundation grants, has been published as 60 articles in international
journals and conference proceedings.

He was involved in plate tectonic theory and deep-sea scientific drilling in the 1970’s. Also
in the 1970’s, an article by Wallace Broecker alerted him to the problem of global warming
caused by the burning of fossil fuels. He has followed that topic closely and taught about it
ever since.

In 1984 he began to study the lahars (volcanic debris flows) of Mayon Volcano in the
Philippines, and introduced the term “lahar” to the Philippines.

After surviving the climactic eruption of Pinatubo Volcano in 1991, he led a multi-agency
effort to study its lahars through the 1990’s, taking early retirement in 1994 to spend more
time on hazard-mitigation research in the Philippines.

His book, “Pinatubo and the Politics of Lahar” won a Philippine National Book Award in
1995.

He continues to study the lahars of Mayon and Pinatubo, but his research now focuses on
land subsidence around Manila Bay caused by overuse of groundwater, and the relative sealevel
rise, worsening rain floods and tidal incursions it causes; and the phenomena of Peak
Oil and Global Warming. He continues to teach courses on hazard mitigation, Peak Oil, and
climate change for the Honors College at UIC, and at the graduate level at The National
Institute of Geological Sciences of the University of the Philippines.