Adding lime to seawater could cut back carbon levels

July 21st, 2008 - 1:49 pm ICT by IANS  


Washington, July 21 (IANS) Adding lime to seawater could dramatically reverse carbon dioxide accumulation in the atmosphere, according to a new study. However, the idea was thought impracticable because of the cost of obtaining lime and the quantity of carbon released in the process.

Gilles Bertherin, of Shell, which is funding the project, said: “There are potentially huge environmental benefits from addressing climate change - and adding calcium hydroxide to seawater will also mitigate the effects of ocean acidification.”

Tim Kruger, management consultant at London firm Corven is the brains behind the plan to resurrect the lime process. He argued that it could be made workable by locating it in regions that have sources like flared natural gas or solar energy in deserts - and that are rich in limestone, making it feasible for calcination to take place on site.

“There are many such places - for example, Australia’s Nullarbor Plain would be a prime location for this process, as it has 10,000 cubic km of limestone,” said Kruger.

The process of making lime generates carbon dioxide, but adding the lime to seawater absorbs almost twice as much carbon dioxide. The overall process is therefore ‘carbon negative’.

‘This process has the potential to reverse the accumulation of CO2 (carbon dioxide) in the atmosphere. It would be possible to reduce CO2 to pre-industrial levels,’ Kruger says.

Klaus Lackner, a researcher from Columbia University, said: “The theoretical CO2 balance is roughly right … it is certainly worth thinking through carefully.”

The oceans are already the world’s largest carbon sink absorbing two billion tonnes of carbon every year. Increasing absorption ability by just a few percent could dramatically increase carbon dioxide uptake from the atmosphere.

These findings were published on Monday in SCI’s Chemistry & Industry magazine.

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