MIT team explores removing CO2 from ocean

The ocean is the world’s largest carbon dioxide ‘sink’, soaking up around 30 to 40 per cent of all of the gas produced by human activities.

Recently, the idea of removing CO2 directly from ocean water has emerged as a possibility for mitigating emissions. Whilst it has not yet led to widespread use, a team of researchers at MIT (Massachusetts Institute of Technology) believes they may have found the key to a ‘truly efficient and inexpensive removal mechanism’. Their findings are published in Energy and Environmental Science.

Existing methods for removing CO2 from seawater apply a voltage across a stack of membranes to acidify a feed stream by water splitting. This converts bicarbonates in the water to CO2 molecules, which can then be removed under vacuum.

T. Alan Hatton, co-author of the paper and Ralph Landau Professor of Chemical Engineering at MIT, noted that the membranes are expensive and chemicals are required to drive the overall electrode reactions at either end of the stack, adding further to the expense and complexity of the processes.