Enhancing the Realism of Decarbonisation Scenarios with Practicable Regional Constraints on CO2 Storage Capacity

Most low-carbon scenarios produced by integrated assessment models deploy substantial amounts of carbon capture and storage (CCS). These models generally assume that CO2 storage is a low-cost and globally ubiquitous resource. Here we challenge this assumption, introducing a CO2 storage potential which accounts for the financial, contractual, and institutional barriers to CO2 storage, which we term the investable potential. We provide a first estimate of this investable potential and utilise a global energy system model to explore the implications for global and regional mitigation pathways. Our results suggest that low-carbon scenarios which assume abundant CO2 storage may substantially overestimate the role of CCS in deep decarbonisation, particularly in key regions such as China and India. Limited CO2 storage leads to mitigation pathways with faster emission reductions and greater reliance on renewable energy for decarbonisation. We demonstrate that the optimal use of CCS depends heavily on the availability of CO2 storage, with different use-cases prioritised at different scales of storage availability. Finally, we present exploratory analysis on the potential for cross-border trade in captured CO2 to match sources and sinks. The results of this analysis can help calibrate expectations and inform policy decisions around the role of CCS in addressing climate change.