Long-term viability of carbon sequestration in deep-sea sediments

Putting carbon dioxide to bed beneath the sea

28 February 2019

Carbon dioxide could be stored safely and permanently by injecting it beneath the seabed of deep oceans.

Trapping greenhouse gases beneath the Earth’s surface is an attractive approach to reducing climate change, but failsafe options are hard to find.

Researchers from Peking University modelled the physical and chemical interactions in sediments to investigate what would happen to liquid carbon dioxide injected 400 metres beneath the seafloor of a 3,500-metre-deep ocean.

Their calculations predict that the low-temperature, high-pressure conditions will cause crystals of carbon dioxide and ice (carbon dioxide hydrate) to form and block the pores in the sediment. This creates an impermeable barrier that prevents carbon dioxide leaking back into the marine environment and the carbon will eventually dissolve into fluids within the pores. The formation of hydrates depends on the underlying rock type, seafloor temperature and water salinity.

The technique could provide a viable, long-term solution to unreliable terrestrial carbon-capture methods.

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References

1. Science Advances 4, eaao6588 (2018). doi: 10.1126/sciadv.aao6588