Hypothetically, "clean coal" plants work by capturing greenhouse gases emitted by coal plants and burying them underground so that the gases won't be released into the atmosphere. Also called Integrated Gasification Combined Cycle (IGCC), these plants have the ability to separate the CO2 so that it won't contribute to global warming. However, "clean coal" plants still bring with them a whole host of environmental issues, including the environmental devastation of mountains, hillsides, and rural areas caused by regular coal mining. Because techniques of burying CO2 have yet to be sufficiently tested, it is unclear whether buried CO2 could leak into groundwater and cause contamination.

David Roberts wrote about the high environmental and financial costs of clean coal on TomPaine.com,

IGCC technology is substantially more expensive than traditional coal plants. Sequestration, which is highly speculative, adds another 30-60 percent to the cost, along with huge new demands for energy and water. Meaningful commercialization and deployment are likely decades away. Even if that bright day arrives, "clean coal" still involves the environmental devastation of coal mining, the generation of substantial mercury and particulate pollution, and a per-kilowatt energy costs no better than wind and far worse than energy efficiency.

The New York Power Authority isn't the first federal agency to realize the prohibitive costs of clean coal technology. Joseph Romm writes on Grist that the Government Accountability Agency estimates that "clean coal" could be prohibitively costly.

The GAO predicts that electricity from clean coal plants will cost up to 78% more than electricity from conventional coal plants, not counting carbon pricing. Clean coal will require construction of pipelines to move carbon from the power plant to the sequestration site, and permanent monitoring, which means extra cost. Meantime, DOE's goals (PDF) are to bring the cost of low-speed wind power down to 3.6 cents a kilowatt hour by 2012, geothermal electricity down to 3-5 cents by 2010, and photovoltaic electricity down to 5-10 cents by 2015. By the time clean coal is market-ready, will it be cost-competitive?

Clearly, having clean, renewable energy is a concern for the future. But why waste our time, money, and energy on "cleaning" up the coal industry when that money could be better spent on less environmentally destructive and cheaper renewable sources?