Coal has been under a lot of fire lately. Environmentalists blame its CO2 emissions for exacerbating climate change. When burned, coal emits mercury into the atmosphere, where it later contaminates lakes and lake fishes. Coal is also a source of noxious air pollutants, like ozone and nitric oxide, which exacerbate asthma and emphysema.
But, coal also provides about one third of the electricity used in the United States, so there is intense effort directed towards seeing if it can be cleaned up. At least one idea has surfaced—what is known as carbon capture and storage, or CCS technology.
Basically carbon capture and storage works like this. A coal-fired power plant operates normally, but the CO2 in its smokestack emissions is separated, captured, and pumped underground. CO2 dissolves in water and forms carbonic acid. Ideally, the carbonic acid reacts with rock minerals, so that the CO2 can’t escape back into the atmosphere.
The technology is not without its problems. Capturing CO2 and pumping it underground uses a lot of energy, so a coal-fired power plant using CCS might need as much as 130% of its normal electricity. And several new studies suggest that pumping CO2 underground could cause small earthquakes. The surface damage from these is likely to be small, but they could crack the rock formations that hold CO2, allowing it to escape back into the atmosphere.
Carbon capture and storage is one of many approaches that will be necessary to reduce our nation’s CO2 emissions, once we get serious about tackling the problems of climate change. And we are far overdue with that assignment.
Photo, taken on August 13, 2005, courtesy of Herry Lawford via Flickr.