Carbon storage hopes rise again

Carbon capture and storage, if it proved possible, would help to make the main greenhouse gas harmless. American scientists say they are making progress.

LONDON, 20th April, 2015 — Two groups of US scientists are exploring new ways of capturing carbon dioxide from the atmosphere. One technology mimics the tree by using artificial photosynthesis. The other exploits a membrane that is a thousand times more efficient than any tree.

Although the nations of the world agreed in 2009 to attempt to limit the global warming temperature rise this century to no more than 2°C above pre-industrial levels, colossal quantities of the greenhouse gas carbon dioxide are still being emitted into the atmosphere.

So some researchers have been exploring the technology of carbon capture and storage (CCS): ways of trapping CO2 as it leaves the power station chimney or machinery exhaust and storing it for burial or reuse. Others have proposed “artificial trees” that could remove the gas from the atmosphere.

Renewable resources

Nanotechnology — engineering at precisions of a millionth of a millimetre — exploits a “forest” of light-capturing “nanowire arrays” dosed with selected populations of a bacterium called Sporomusa ovala to filter the flue gases for carbon dioxide. This inventive double act of silicon and a carbon-based life form then performs a conjuring trick called photo-electrochemistry: from the captured gas it delivers acetic acid, and it can go on doing so for about 200 hours.

A second bacterium — genetically engineered Escherichia coli — can then get to work on the product and turn it into acetyl co-enzyme A as the starting point for a range of valuable chemical products. These could range from a precursor to the anti-malarial drug artemisinin to the fuel butanol.

Storage problem

Klaus Lackner of Arizona State University’s Centre for Negative Carbon Emissions and colleagues are testing a synthetic membrane that can capture carbon dioxide from the air that passes through it.

The technology is based on a resin that works in dry atmospheres (in humid environments it actually releases the carbon dioxide, so it wouldn’t work everywhere). Prototype collectors trap between 10% and 50% of all the carbon dioxide that blows through the membrane.

“I believe we have reached a point where it is really paramount for substantive public research and development of direct air capture,” he told the American Physical Society meeting in Maryland. “The Centre for Negative Carbon Emissions cannot do it alone.” — Climate News Network

Read the full story at www.climatenewsnetwork.net/carbon-storage-hopes-rise-again/

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