Underground Water for Carbon Capture, Scientists Suggest

Underground water supplies could play a part in absorbing carbon emissions in the fight against climate change, on the basis that they’ve already being trapping CO2 for multiple millennia, scientists stated at the beginning of April.

This discovery – according to the University of Manchester’s Chris Ballentine, one of those involved in a recent study – paves the way for subterranean, aqueous carbon capture to take place, so long as the local geology permits it. 

Suitable sites – Ballentine advised news agency Reuters – would be those with water systems located many kilometres below ground – far enough down to guarantee none of the emissions intended for capture can make it into the atmosphere.

“Clearly we want to bury carbon dioxide in the ground, that is a no-brainer”, Ballentine explained.

"The big question is when we put carbon dioxide into the ground, how safe is it?”

Controlling CO2 Emissions

With forecasts of sea levels increasing, global temperatures rising and violent weather patterns, scientists around the world are assessing ways of controlling CO2 emissions, together with those of other greenhouse gases.

Carbon capture has many advocates, but, as a process, has not been attempted on a large-scale basis, due to its associated cost.  To put the financial aspect into context, capturing the carbon released by one fossil fuel power plant would cost in the region of one billion Euros.

Harnessing Carbon Capture Technology

Despite this, anyone capable of harnessing carbon capture technology cheaply will likely profit enormously; in China, for example, coal-based power stations are opening up on a weekly basis, while the world’s coal reserve is potentially sufficient to last several centuries.

In their study, Ballentine et al looked at how water absorbed CO2, and compared this to an alternative method at nine locations around the world – sites that volcanic activity released carbon into when they erupted in or around prehistoric times.

Here, the scientists discovered that the primary carbon sink was water located deep underground and, since this had been taking place for such a long time, their study highlighted the prospect of these kinds of sites being drawn upon in order to slow down global warming.

Previous studies into carbon capture drew attention to the CO2 absorbing properties of subterranean rocks.  This one, however, differed in explaining that water, and not rocks, held the CO2 tight.

“By combining two techniques, we've been able to identify exactly where the carbon dioxide is being stored for the first time," another of the researchers involved,  Stuart Gilfillan, stated, adding: “Our study clearly shows that the carbon dioxide has been stored naturally and safely in underground water in these fields.”