CCS numbers systemically overestimated – Imperial study

A new study from Imperial College London has found that the amount of CO2 sequestered by carbon capture and storage (CCS) from 1996-2020 has been overestimated by up to 30 per cent.

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Published in Environmental Science & Technology Letters, the report outlines the significant role that CCS has played in climate change mitigation. However, it also warns that the reporting mechanisms used to quantify its impact are leading to skewed figures, which could ultimately undermine the technology’s role in tackling the climate crisis.

According to the Imperial team’s calculations, CCS has removed 197 million tonnes of CO2 from the atmosphere between 1996 and 2020. This falls short of official reports by 19-30 per cent, giving an inaccurate picture of the technology’s contribution to fighting climate change.

“Carbon capture and storage is rightly a cornerstone of climate change mitigation, but without a centralised reporting framework we approach climate change on the back foot when we need to be more proactively tackling the issue with robust and accurate reporting,” said lead author Yuting Zhang, PhD candidate at Imperial’s Department of Earth Science and Engineering.

“Policymakers should embrace a centralised reporting database that includes rates of carbon capture, transport, and storage, including quality assurance measures like independent auditing.”

One key problem with CCS reporting is that nameplate capacity is generally used as a yardstick, as opposed to the actual amount of CO2 captured and stored. The Imperial report claims that, as of 2021, global capacity was at 40 million tonnes across 26 CCS facilities. However, as no core framework exists globally to compel the reporting of precise amounts of carbon captured, actual rates of capture, transport, and storage are not centrally reported.

“Carbon capture has the potential to significantly alter the planet’s fate, but unclear guidance means there’s no international consensus on how much has been stored so far, save for academic calculations. We urgently need clearly defined parameters so we know exactly where we stand,” said senior author Dr Samuel Krevor from Imperial’s Department of Earth Science and Engineering.

“The nearly 200m tonnes of climate-warming carbon removed from the atmosphere is significant, but reaching this figure should not have relied on academic research.”

The Imperial researchers say that requiring facilities to report actual capture rates would tell us more precisely how well CCS is working and put us in a much better position to address the climate crisis. While the gaps between capacity and actual storage were sometimes due to project performance issues, this was not always the case. The discrepancies also arose from changes over time in the source of CO2 and variations in the definition of capture capacity used by projects.