Thursday, October 8, 2009

Carbon Capture and Storage

Carbon capture and storage (CCS) is just what the phrase would indicate; capturing carbon in the form of carbon dioxide (CO2) emitted say, by coal-fired power plants, and storing it in places where, theoretically, it will remain, if not forever, then for long enough to allow the world's green house gas emissions to be brought under control. Storage, also termed sequestration, may be in subsurface saline aquifers, reservoirs, ocean water, aging oil fields, or other carbon sinks. Interestingly, nature, if left alone to do its job, sequesters an enormous amount of CO2 (biological sequestration). Unfortunately, man seems hell bent on either overloading nature's "sinks," or destroying them.

The surface ocean currently absorbs about one-fourth of the CO2 emitted to the atmosphere by human activities from fossil fuel combustion, among other things. As this CO2 dissolves in seawater, it forms carbonic acid, increasing ocean acidity. Since industrialization began in the 18th century, surface ocean acidity has increased by 30%. High acidity is already causing serious damage to ocean ecosystems. It could ultimately severely and irreparably damage marine food webs and lead to drastic reductions in commercial fish stocks. The current increase in ocean acidity is a hundred times faster than any previous natural change that has occurred over the last many millions of years.

At the same time we're overloading the oceans with man-made CO2, we're destroying other natural CO2 sinks. Each day at least 80,000 acres of rainforest disappear from Earth. At least another 80,000 acres of forest are degraded. As these forests fall, more carbon is added to the atmosphere.

Research and development by government and industry (including the Pacific Northwest National Laboratory) has been aimed at developing CCS systems specifically designed to remove carbon dioxide from the flue gases and various process streams of large power plants and industrial facilities and safely deposit the carbon dioxide in secure storage sites deep underground – thus keeping it out of the atmosphere.

Vattenfall AB, a large Swedish energy company, has plans to store millions of tons of CO2 in saline aquifers under the rolling fields of eastern Germany, but local opposition may thwart these plans. People are frieghtened that the gas may escape and poison them, or blow up and send them prematurly to Valhalla. And the technology is expensive, in the billions of dollars. Without some way to artificially raise the cost of carbon, say through cap and trade, CSS is currently not economical.

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