Captured carbon must be stored for at least 1,000 years to tackle climate change

Jack Loughran Tue 12 Nov 2024

Collected at: https://eandt.theiet.org/2024/11/12/captured-carbon-must-be-stored-least-1000-years-tackle-climate-change-study

Carbon capture and storage (CCS) technologies are only viable if the carbon sequestered is stored ‘durably’ for at least 1,000 years, a study has found.

CCS technology concentrates carbon emissions and stores them beneath the seabed under pressure. It can be used to capture emissions at source or absorb airborne carbon as a way to remove the emissions already released into the atmosphere historically.

The Intergovernmental Panel on Climate Change has specified that the removed atmospheric CO₂ has to be stored ‘durably’ so that it is not released back into the atmosphere. But interpretations of the exact time period of a durable storage medium have varied from decades to millennia.

A new study  released in Communications Earth & Environment has calculated that if emissions captured from historical fossil fuel burning were only stored for 100 years, the planet could see additional warming of 1.1°C by 2500 compared to permanent storage, thus putting internationally-agreed-upon temperature limits at risk.

“To date, there is little agreement and scientific research on what ‘durably’ corresponds to or what CO₂ storage duration is required to fully neutralise residual CO₂ emission under a net zero framework,” the researchers said. 

“However, a threshold between temporary and durable removals is important for robust carbon dioxide removal policy. Our findings suggest that a CO₂ storage period of less than 1,000 years is insufficient for neutralising remaining fossil CO₂ emissions under net zero emissions.”

They add that shorter duration storage could still be useful in some cases, such as when neutralising CO₂ from land use changes and forestry sectors where carbon will eventually be returned to similar stores from which it was emitted. It could also be useful for counterbalancing other greenhouse gases – such as methane – which has a significant warming factor but dissipates in the atmosphere after just a few decades.

Last month, the UK government announced it would invest nearly £22bn  in CCS projects over the next 25 years as part of broader plans for the UK to achieve net zero carbon emissions by 2050. 

The decision faced criticism from scientists and environmental campaigners, who said the technology was unproven and will extend the reliance on fossil fuels.