A prudent planetary limit for geologic carbon storage - Nature

"Net-zero CO 2 emissions will occur when gross sources of CO 2 equal removals by sinks. Carbon capture and storage (CCS) has a role in both reducing sources (through, for example, storing captured CO 2 from cement production and fossil-fuel combustion) and durably removing CO 2 from the atmosphere (for example, storing CO 2 captured from the atmosphere or biomass combustion). Despite its prominence in scientific and policy discourse, present deployment of CCS is small, with 49 MtCO 2 yr −1 of capture capacity in operation and 416 MtCO 2 yr −1 either planned or in construction10."

"Almost all facilities are planned to store carbon in sedimentary rock formations, the focus of our analysis, with the largest planned basalt-based storage facility having a capacity of less than 0.036 MtCO 2 yr −1. The majority of operational storage facilities are utilized for enhanced oil recovery, a process that overall results in net-positive CO 2 emissions11. However, the technical potential for geologic carbon storage is commonly assumed to be vast, with estimates of available storage of around 10,000-40,000 GtCO 2 in the scientific literature3,12."

Storing carbon in geologic formations for centuries to millennia is required to meet Paris Agreement temperature goals. Reaching net-zero CO2 stops temperature increases; pursuing net-negative CO2 and net-zero GHG emissions could enable temperature declines. CCS can both reduce emissions from industry and fossil fuels and durably remove CO2 from the atmosphere or biomass. Current CCS deployment is small (49 MtCO2/yr operating; 416 MtCO2/yr planned or under construction). Most planned storage targets sedimentary rocks; many operational sites use enhanced oil recovery, which yields net-positive CO2 emissions. Technical storage estimates range from about 10,000–40,000 GtCO2.

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