The feasibility of reaching gigatonne scale CO₂ storage by mid-century

The Sixth Assessment Report by the Intergovernmental Panel on Climate Change projects subsurface carbon storage at rates of 1 - 30 GtCO₂ yr^-1 by 2050. These projections, however, overlook potential geological, geographical, and techno-economic limitations to growth. We evaluate the feasibility of scaling up CO₂ storage using a geographically resolved growth model that considers constraints from both geology and scale-up rate. Our results suggest a maximum global storage rate of 16 GtCO₂ yr^-1 by 2050, but this is contingent on the United States contributing 60% of the total. These values contrast with projections in the Sixth Assessment Report that vastly overestimate the feasibility of deployment in China, Indonesia, and South Korea. A feasible benchmark for global CO₂ storage projections, and consistent with current government technology roadmaps, suggests a global storage rate of 5-6 GtCO₂ yr^-1, with the United States contributing around 1 GtCO₂ yr^-1.