Getting cagey about CO2

Petroleum engineers are developing technology designed to remove a potential obstacle to under-sea storage of carbon dioxide emissions.

Carbon capture and storage were high on the agenda in last week's Budget when Gordon Brown launched a consultation process to identify barriers to its widespread use. Prof Bahman Tohidi and his team at Heriot Watt University's Institute of Petroleum Engineering believe a natural physical process could solve the problem of CO2 leakage after it has been buried.

Instead of allowing CO2 emissions from power stations to escape to the atmosphere, it has been suggested they could be trapped and delivered by pipeline to a suitable underground storage site, such as an exhausted oil or gas field beneath the sea. However, if the cap rock holding the CO2 leaked, this would pose a problem: the escaping gas would make the sea more acidic, raising the threat of an environmental disaster.

Tohidi believes that, if the conditions were right, any leaking CO2 could form hydrates with the water, blocking the gaps between particles in the sediment and providing a secondary seal. 'Even if the cap rock breaks, this would prevent the CO2 escaping into the ocean,' he said. 'It would provide security, and reduce worries about changing the ecology of the ocean.'