Techno-economic insights and deployment prospects of permanent carbon dioxide sequestration in solid carbonates†

While a rapid defossilisation of the energy-industry system is at the highest priority for climate change mitigation, additional post-fossil carbon dioxide removal (CDR) for net-negative emissions will likely be necessary to ensure a safe future. An in-depth techno-economic analysis of differentiated sequestration options for carbon dioxide (CO₂) in solid carbonates is not yet available, as direct air capture-based mineralisation is usually aggregated in direct air capture and carbon sequestration. This research gap is closed by studying mineralisation as a key CDR option to sequester atmospheric CO₂ permanently, based on available literature. The most frequently discussed routes for mineralisation, i.e., in situ, ex situ mineralisation, and enhanced rock weathering, are examined. The deployment potentials of these options are determined globally for nine major regions. Results indicate that costs for all mineralisation options can be kept below 100 € per tCO₂ from 2050. From 2030 onwards, in situ mineralisation, with low energy-intensity, can be realised at cost of ≤131 € per tCO₂, ex situ mineralisation at ≤189 € per tCO₂, and enhanced weathering at ≤88 € per tCO₂. Final energy demand for CO₂ sequestration via in situ mineralisation is ≤1.8 MWh per tCO₂, via ex situ mineralisation ≤3.7 MWh per tCO₂, and via enhanced weathering ≤1.1 MWh per tCO₂ from 2030. Large-scale deployment of mineralisation options supporting 60% of projected CDR demand is assessed to require up to 0.06% and 0.21% in global gross domestic product and up to 2.5% and 8.6% additional primary energy demand in 2070 for a 1.5 °C and 1.0 °C climate target, respectively. Implications, permanence of sequestration, and limitations are discussed, and a research outlook is provided.