Beyond the Catch-All Rhetoric: Making Sense of Clean/Dirty ‘Clean Coal’

The effort to decarbonize the atmosphere in coming decades basically comes down to two grim challenges: drastically reduce carbon emissions, or drastically reduce energy consumption.

Given that the world’s population is expected to increase by a few billion more people by 2050, the energy consumption piece is a bit of a wild card. So experts and policymakers are getting serious about “clean coal,” a catch-all phrase dear to the hearts of industry public relations officials and a term meaning so many things, and different things, to different people. In addition, it’s a concept that exists only in a few places.

A Little History:
Going Back to World War II

Coal is inherently dirty, both to mine and after it’s burned. But it’s also abundant and, so long as economic externalities are not considered, it can be economical. Furthermore, coal currently provides half of the electricity in the United States, where the industry and its work force have substantial political clout.

The following outlines basics of “clean coal” technologies and identifies resources for more information on a subject certain to be at the heart of energy and climate change policy considerations for decades to come.

What the technology does

Carbon capture and storage
(aka carbon capture and sequestration or CSS)

Prevents carbon dioxide from leaving the stack and transfers it to underground vaults or to ocean disposal. Ways to capture CO2 are either “pre-combustion” or “post-combustion.”

One method pipes the carbon dioxide to underground oil wells, where the pressure allows more of the oil to be extracted than otherwise. Another sends the CO2 to an aquifer or underground to be turned into methane, which can then be returned to the plant to burn.

Coal washing

In practice for many decades, it removes impurities like excess ash and sulfur before burning by crushing coal, screening it, and, sometimes, submerging it in liquid.

Coal gasification

Using steam, pressurized air or oxygen, forces coal’s carbon molecules apart, resulting in a synthetic gas that can be burned in a turbine.

Wet scrubbers, or flue gas desulfurization systems

Came into wide use after the 1990 Amendments to the Clean Air Act. Removes sulfur dioxide from gas after coal burns by spraying water and lime before the emissions leave the stack.

Environmental impacts

Carbon capture and storage
(aka carbon capture and sequestration or CSS)

Long-term impacts, such as leakage of CO2 out of rock, are still not known.

Coal washing

After cleaning, coal emits less sulfur when burned. But to provide the same amount of energy as with unwashed coal, a plant must start out with more coal to begin with. Coal washing sends residues into holding ponds and waterways.

Coal gasification

Extremely energy intensive process to force the molecules apart.

Wet scrubbers, or flue gas desulfurization systems

Greatly reduces sulfur and nitrogen oxides ( “SOx and NOx” ). Obviously, much better for the air than stacks without them. Does not capture carbon dioxide, but the industry includes the technologies that “scrub” SOx and NOx in its definition of clean coal and does not consider CO2, since no national regulations yet apply to it.

Example of current research

Carbon capture and storage

The DOE’s National Energy Technology Laboratory researchers Dr. Todd Gardner and Dr. Victor Abdelsayed are studying a low-energy way to convert CO2 into useful energy using catalytic converters. They were scheduled to speak at the American Chemical Society National Meeting March 21-25, 2010, in San Francisco. See also “Economic impacts,” below.

Coal gasification

Research is focusing on how to use many fuels, from biomass to trash to coal, in gasification. DOE is also studying ash content and temperatures.

Wet scrubbers, or flue gas desulfurization systems

Scientists are trying to find a way to remove more elemental mercury.

Where it’s in use in the U.S.

Carbon capture and storage

Demonstration project at the Pleasant Prairie Power Plant in Wisconsin captures about 1.5 percent of that plant’s CO2.

Systems that send CO2 underground to improve oil well yields are in use in Texas.

CCS is planned for the FutureGen project in Illinois – see coal gasification.

The federal American Recovery and Reinvestment Act, the economic stimulus legislation, has awarded $22 million for several new projects in Louisiana, Mississippi, and elsewhere.

Coal washing

Coal preparation plants crush and screen coal all over the country. Washing of coal is more common in the eastern United States.

Coal gasification

Planned for the federal government’s recently revived FutureGen project in Mattoon, Illinois (which would also be the first U.S. plant capturing and storing all of its CO2.)

Wet scrubbers, or flue gas desulfurization systems

Since the 1990 Clean Air Act Amendments, plants and industrial complexes have been required to phase in wet scrubbers.

Other countries

Carbon capture and storage

Statoil’s Sleipner Project in the North Sea captures CO2 that is separated from the project’s natural gas production stream and injects it back into the permeable rock beneath the seabed.

Coal washing

India practices coal-washing but has struggled to improve methods. China now uses coal washing for about 15-20 percent of its coal. Poland is starting to use the technique to clean its relatively low-quality coal.

Coal gasification

In use in Europe, Japan, and Australia. China is experimenting with an underground gasification demonstration project.

Wet scrubbers, or flue gas desulfurization systems

Scrubbers are in wide use in many industrialized countries.

Economic impacts (costs and benefits)

Carbon capture and storage

The technology is well understood but not in wide use. It’s still more expensive to send CO2 underground than it is to buy emissions permits on the emerging emissions trading market, says Daniel P. Schrag, a Harvard professor studying CCS efficiency. Schrag and three colleagues at Harvard and MIT estimate that a power plant loses between 11 and 40 percent of its energy to the effort of capturing and moving the CO2 – with 29 percent a realistic goal, given challenges of capturing and storing CO2.

Coal gasification

Commercial gasification plants run at about 40 percent efficiency now, or roughly comparable to conventional coal boilers, but the Department of Energy thinks gasification could reach 60 percent efficiency in the future. That would, it says, cut CO2 emissions by 40 percent.

Wet scrubbers, or flue gas desulfurization systems

Scrubbers represent the difference between doing business and having to cease operations, as most plants grandfathered out of the regulations in the U.S. are nearing the end of their useful life, and they must either upgrade or rebuild.

Remaining hurdles

Carbon capture and storage

Virtually nothing is funded or built yet. In order to make progress in reducing emissions, the experts say that many projects must get started soon. Half of the United States’ electricity comes from coal. Cutting the cost is the key to using CCS. A major consideration, coal researchers believe, will be whether nuclear power takes off again in the face of high costs and continued political opposition in some quarters.

Coal washing

Current techniques to clean coal before burning do not remove enough sulfur to comply with most environmental regulations.

Coal gasification

Finding a way to cut the cost of gasification. Most commercial gasifiers cannot effectively use more than one type of fuel, or feedstock, at this point.

Wet scrubbers, or flue gas desulfurization systems

N/A

Major milestones

Carbon capture and storage

Citizens are still skeptical of the need for such a major change in technology, the U.S. Department of Energy reported in a January best-practices manual.

For further information

Carbon capture and storage

Carbon sequestration atlas, http://www.netl.doe.gov/technologies/carbon_seq/refshelf/atlas/.

World Energy Council is a U.K.-based nonprofit promoting new energy technologies. Some helpful background:

U.S. Department of Energy on January 13 released a best-practices manual on carbon capture and storage projects. (See http://www.netl.doe.gov/publications/press/2010/10002-DOE_Publishes_Best_Practices_Manua.html)

The CCSReg Project website includes slides and background on CCS technology, http://www.ccsreg.org/working_papers.html

Coal washing

India Environmental Portal, http://www.indiaenvironmentportal.org.in/node/249190

Coal gasification

For more on the FutureGen plant, see http://fossil.energy.gov/programs/powersystems/futuregen/index.html

Explanation of gasification technology at http://fossil.energy.gov/programs/powersystems/gasification/howgasificationworks.html

The U.S. Department of Energy’s gasification research site: http://www.fossil.energy.gov/programs/powersystems/gasification/gasificationresearch.html

Wet scrubbers, or flue gas desulfurization systems

Trade journal, http://coalgasificationnews.com/


A Little History:
Going Back to World War II

The quest to burn coal cleanly goes back many years, at least to the 1920s, and the history is messy and expensive. Germany made a liquid fuel out of coal during World War II because the country had no source of petroleum to power its vehicles or airplanes. The United States appeared keen to use its abundant coal reserves for liquid fuel, too, and it passed the Synthetic Fuels Act in 1944, before the war had ended.

But making coal into cleaner fuels was expensive and energy-hogging. By 1953, the U.S. Department of Energy has recounted in an online history, the government killed funds for new synthetic fuel plants in Missouri. A key consideration involved competition between coal and then-low-cost oil. “A short time later, the Committee voted to cease funding for all the programs authorized under the Synthetic Fuels Act.” Oil was cheap by then, and remained so for decades.

You might say the rest was history, but oil has not been cheap for several years now, and the difficulties of extracting it from deep-ocean wells or energy-sucking oil shale operations in Canada have made clear that it is unlikely to be cheap over the long run. In addition, throughout Appalachia in particular, the practice that has come to be known as “mountain top removal” has stirred great controversy among local residents and has served as a national rallying cry for interests eager to restrict long-term reliance on coal.

Some Useful Links on ‘Clean Coal’

University of Colorado environmental studies professor Roger Pielke Jr.’s blog. See this posting from a few months ago: http://rogerpielkejr.blogspot.com/2009/10/our-coal-fired-future.html.

The Reality Coalition’s sarcastic video on YouTube: http://www.youtube.com/watch?v=PdHuB7Ovl2o&NR=1

U.S. Department of Energy’s Clean Coal site: http://fossil.energy.gov/programs/powersystems/cleancoal/index.html

University of Illinois Carbon Capture Report. This uses automated searches to list any news story mentioning coal or clean coal or related topics, day by day. The reports are a reminder that the press could be doing more. http://www.carboncapturereport.org/

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Christine Woodside

Christine Woodside is a freelance writer living in Deep River, Connecticut. Twitter: @chriswoodside)
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2 Responses to Beyond the Catch-All Rhetoric: Making Sense of Clean/Dirty ‘Clean Coal’

  1. Dan Rogers says:

    “Coal is inherently dirty, both to mine and after it’s burned.”

    Until that fallacy is put to rest we are not going to be able to have a sensible American energy policy. Coal is a black substance, it is true, and ity will make you dirty if you rub it on yourself, but so is petroleum and charcoal and a lot of other things that can be burned to produce energy.

    When I was a boy in the Pittsburgh area, everyone burned bituminous coal for home heating, and that made for some really sooty and foggy days in the wintertime. After World War II ended, State and municipal smoke control ordinances eliminated that “dirty” aspect of coal combustion, and since that time the controls imposed by the Clean Air Act have proved effective in cleaning up the particulate pollution that gave our town the “Smoky City” moniker. Now the air in western Pennsylvania is as clean as anyone could want.

    So coal is no longer dirty to burn. It may still be dirty to mine, but far fewer miners are needed to produce the coal we mine, so fewer people get dirty mining it. (Showers are provided for the use of those coal miners who are so fastidious that they do not want to go home dirty. Times have changed since “How Green Was My Valley.”)

    Ms. Woodside undoubtedly refers to coal as a “dirty” energy source because burning it produces carbon dioxide. But there is nothing “dirty” about carbon dioxide. It is a colorless and odorless gas which exists only in minuscule concentrations in the air we breathe, and it is absolutely essential to the existence of all oxygen-consuming plant and animal life on our planet.

  2. “But there is nothing “dirty” about carbon dioxide. It is a colorless and odorless gas” which just happens to be the primary greenhouse gas contributing to global warming. The “small quantities” in the atmosphere are out of balance with the the Earth’s capacity to absorb it due to burning of fossil fuels.