Detecting the leaks

31 March 2020

Carbon capture and storage (CCS) requires an unprecedented effort to store gigatonnes of carbon dioxide in the earth’s subsurface. But as US researchers point out, critical to the adoption and success of CCS is the protection of valuable water resources that could be impacted by leaking CO₂ from CCS operations.

31st March 2020

Safeguarding precious water resources, while storing CO₂ to protect the planet, requires that both the appropriate technical tools and societal controls be developed and evaluated to maximise the benefits of CCS while limiting any potential negative impact.

Using a naturally leaking CO₂ system located at Soda Springs, Idaho, US, researchers have been able to use the site as an analogue for industrial CCS deployment as the CO₂ is present at depths and temperatures expected in large scale CCS systems.

The researchers have been able to leverage this natural CO₂ storage to look at three potential failure models for CCS systems by applying rare earth elements, supported by major elements and isotopes, as aqueous geochemical tracers of subsurface geofluids. The research team explains ‘…the addition of large volumes of CO₂ in CCS operations will alter brine chemistry by decreasing pH and promoting increased water-rock interactions. The geochemical signatures imparted to the formation fluids by these reactions could be a useful tracer for fluid migration, both within the formation and, should it migrate, the overlying formations.’

The research team concludes that the many naturally CO₂ leaking analogue sites distributed around the world, provide important opportunities to assess implementation impacts of and test monitoring strategies for industrial scale CCS production.

‘The effective implementation of a robust CCS groundwater monitoring strategy requires a detailed understanding of the regional hydrochemistry and should be part of the site selection and characterisation process,’ the research team stressed.

Greenhouse Gases Science and Technology: DOI: 10.1002/ghg.1949

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