We all know that fossil fuels are dirty business. Can carbon capture and sequestration technologies help to make “clean coal” a reality? The answer is as complicated as the technology itself, which is still largely under development, but many vocal critics claim that the promise of clean coal is no more real than the lump of coal Santa is supposed to give naughty children at Christmas.

Currently, carbon dioxide (CO2) is routinely separated and captured as a by-product from industrial processes such as synthetic ammonia production, hydrogen production, and limestone calcination. However, when it comes to capturing it from coal (and natural gas) plants, the process becomes more complicated, as the CO2 must be extracted from flue vents (or other “source points”), and once harvested, must be disposed of, either by deep geologic or ocean storage, or recycling through various products, such as fuel, plastics, cement, and fertilizers.

According to the U.S. Department of Energy, existing capture technologies are not cost-effective when considered in the context of sequestering CO2 from power plants. The government hopes to bring those costs down through improved research, but at present, the technology uses 10-40% of the power produced by a power plant, which–if widely adopted–has the potential to drive up the demand for coal and erase many of the efficiency gains of the last 50 years.

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Clean coal” has, nevertheless, been a recent rallying cry by the coal industry, which claims that since capture research has already significantly improved the environmental performance of coal-based generation for traditional emissions such as SO2, NOx and particulate matter, CO2 is simply the next on the list. A number of private companies, buoyed up by Department of Energy carbon capture research funding, have been working to make that goal a reality by developing improved carbon capture and sequestration technologies.

One of those companies is Skyonic, which has been operating a plant demonstrating its SkyMine technology since 2007 at various locations in Texas, including in conjunction with Capitol Cement in San Antonio, in preparation for its first commercial pilot plant that is due for completion in 2012. It will recycle CO2 captured from various industrial processes in the form of commercially saleable mineral products.

Has the data from the demonstration plants, so far, proven that mineralized CO2 can be a cost-effective solution to carbon capture? While the San Antonio Skymine plant is still undergoing testing and sending out samples to potential customers, Stacy MacDiarmid, Director of Communications for Skyonic, told us, “While Skyonic’s SkyMine technology is profitable, and thus implementable before government regulation of carbon, Skyonic still believes that carbon regulation is a near-future necessity, and will help spur further development and achievement in the field.”

Despite this assertion, many environmental groups believe that carbon capture and sequestration technology is a waste of U.S. taxpayer money, and worse, a distraction from the necessity of creating a future based on renewable energy. Gabriel Wisniewski, Coal Campaign Director for Greenpeace USA, told us, “The American Coalition of Clean Coal Electricity, the American Coalition for Clean Coal Electricity and other coal industry lobby and PR groups have spent tens of millions of dollars trying to convince American policymakers, media, and the public that coal is a clean energy source. Their website declares that ‘it works.’ But slick advertising doesn’t make their claim any more true. Carbon capture and sequestration has simply never been proven to work—let alone to be permanent or safe—at a commercial scale.”

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He goes on to note that there are major doubts as to whether there are enough deposits to store all the captured carbon through geologic storage (which has also been shown to pose a danger to both humans and animals in the case of leakage) and that because investors have generally balked, even testing carbon capture and storage technologies at meaningful scale would cost billions of taxpayer dollars–money better spent on “real solutions” like wind and solar.

The entire Greenpeace report on “clean coal” is available online, as is the MIT report on the feasibility of carbon capture and storage technologies, The Future of Coal.

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