Clean coal is the name attributed to coal chemically washed of minerals and impurities, sometimes gasified, burned and the resulting flue gases treated with steam, with the purpose of almost completely eradicating sulfur dioxide, and reburned so as to make the carbon dioxide in the flue gas economically recoverable. The coal industry uses the term "clean coal" to describe technologies designed to enhance both the efficiency and the environmental acceptability of coal extraction, preparation and use. This time frame is of concern because there is an urgent need to mitigate greenhouse gas emissions and climate change to protect the world economy according to the Stern report. Even when CO₂ emissions can be caught, there is considerable debate over the necessary carbon capture and storage that must follow.

Byproducts
Examples of clean coal usage include the proposed US FutureGen plant — planned to be a near zero-emissions coal-fired power plant, but is still years away from commercial operation (expected 2012) and whose commercial viability is unknown.
It is also believed that some process similar to the natural gas fuel cell or microbial fuel cell (charged from biomass or sewage) may be practical using coal as fuel. These technologies are used mostly for stationary fuel cells as charging is slow. A large power plant in a coal mine might be the most energy-efficient approach and require the least transport of coal to the users. The return of the coal chute and its use in homes may be possible in some places, especially if home sewage or natural gas lines can be tapped as well by an improved fuel reformer technology such as that already used to convert methanol or gasoline to the natural gas form.

Potential uses of clean coal
In Carbon capture and storage under "Cost of CCS" lifetime costs for natural gas, pulverized coal and IGCC with and without carbon capture are detailed.
In a study conducted in 2003 by the IEA GHG, "the capital cost of building a Shell-designed IGCC could cost $1371 per kW-electric without carbon capture and $1860 with it."
Comparisons with other energy sources can be found in Economics of new nuclear power plants.

Support
Prominent environmentalists including Dan Becker, director of the Sierra Club's Global Warming and Energy Program, believe that the term clean coal is misleading: "There is no such thing as 'clean coal' and there never will be. It's an oxymoron".

See also

Innovative Silesian Cluster of Clean Coal Technologies
Coal Online - Free information on Clean Coal technology
BBC News - Clean coal technology: How it works
International Energy Association - Clean Coal Centre
World Coal Institute - Coal: Facts & Figures
US Department of Energy's clean coal technology web page
CNNMoney story on clean coal economics
"Beyond Kyoto" Initiative
National Energy Technology Laboratory compendium homepage
Uranium Information Centre paper on "Clean Coal" Technologies
Remarks of Senator Hillary Rodham Clinton to the Cleantech Venture Forum VIII
SaskPower Clean Coal Project
Air preheater cleaning resulting in better emissions management
Clean coal facts and figures page by Rising Tide Newcastle
EU: Large combustion plants air pollution regulation