What is 'clean coal,' anyway?

Call it a hat trick: The phrase "clean coal" turned up in all three presidential debates, with both McCain and Obama supporting it. It turned up four times if you count the vice-presidential debate.

And woe betide any politician who doesn't appear to be in favor of it. Speaking Tuesday in Joe Biden's hometown of Scranton, Pa., Sarah Palin blasted the Democratic vice-presidential candidate for telling an activist in Ohio last month that the Obama campaign doesn't support clean coal. Biden says that his comments, which were posted on YouTube, were taken out of context. Since then, Biden has been emphasizing his pro-clean-coal Senate record, and reiterating his and Obama's support for the stuff.

But what exactly is clean coal? And why are all the candidates so quick to proclaim their support for it?

To answer both those questions: It's a vague concept with positive connotations. And it's a vague concept with positive connotations.

"Clean coal" means different things to different people, and the meaning seems to shift over time. Prior to World War II, the term was sometimes used to describe the high-quality "smokeless coal" that was sold for use in the home.

Later in the 20th century, the term morphed into something new. The 1990 Clean Air Act  defined clean coal technologies as those that achieve "significant reductions in air emissions" of sulfur dioxide and nitrogen oxides, pollutants that contribute to the formation of acid rain. Utilities sought to effect these reductions through a variety of means, including the use of low-sulfur coal, acid gas scrubbers, electrostatic air cleaners, and the development of higher-efficiency combustion techniques to squeeze more electricity out of each lump of coal.

A glossary on the website for the American Coalition for Clean Coal Electricity, an advocacy group backed by coal mining and utility companies, sticks to this definition:

Clean coal technology: Any technology to reduce pollutants associated with the burning of coal that was not in widespread use prior to the Clean Air Act Amendments of 1990.

1 | 2

Next