Adding lime to seawater may reduce CO2 in the atmosphere to pre-industrial levels

Washington, July 21 : Scientists have said that they have found a workable way of reducing CO2 (Carbon dioxide) levels in the atmosphere to pre-industrial levels by adding lime to seawater.

The oceans are already the world's largest carbon sink, absorbing 2 billion tonnes of carbon every year. Increasing absorption ability by just a few percent could dramatically increase CO2 uptake from the atmosphere.

Adding lime to seawater increases alkalinity, boosting seawater's ability to absorb CO2 from air and reducing the tendency to release it back again.

However, the idea, which has been bandied about for years, was thought unworkable because of the expense of obtaining lime from limestone and the amount of CO2 released in the process.

Now, Tim Kruger, a management consultant at London firm Corven, made this process possible.

He said that it could be made workable by locating it in regions that have a combination of low-cost 'stranded' energy considered too remote to be economically viable to exploit - 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.

According to Kruger, "There are many such places - for example, Australia's Nullarbor Plain would be a prime location for this process, as it has 10 000km3 of limestone and soaks up roughly 20MJ/m2 of solar irradiation every day."

The process of making lime generates CO2, but adding the lime to seawater absorbs almost twice as much CO2. The overall process is therefore 'carbon negative'.

"This process has the potential to reverse the accumulation of CO2 in the atmosphere. It would be possible to reduce CO2 to pre-industrial levels," said Kruger.

Shell is so impressed with the new approach that it is funding an investigation into its economic feasibility.

"We think it's a promising idea," said Shell's Gilles Bertherin, a coordinator on the project.

"There are potentially huge environmental benefits from addressing climate change - and adding calcium hydroxide to seawater will also mitigate the effects of ocean acidification, so it should have a positive impact on the marine environment," he added.

ANI