Cost‑effective offshore carbon capture, utilization and storage deployment and transport network optimization in southern China

High-emission, high-economic-density coastal regions require viable pathways to reach net-zero carbon dioxide emissions. Here we develop a phased deployment framework for offshore carbon capture, utilization and storage in southern China. Using a two-stage numerical optimization model integrating geological constraints with geographic information systems-based network optimization, we assess a 2023 emissions inventory from 23 cities compiled from public statistical yearbooks and offshore storage potential. Techno-economic analysis shows that under a medium carbon-price scenario, offshore carbon capture, utilization and storage projects can achieve positive annual net benefits around 2037, and nearly all blocks are expected to turn annually profitable before 2040. Offshore carbon capture, utilization and storage can support coastal regions with high economic density in taking on a larger share of emission reductions. Attention should be paid to optimizing transportation distances. This work provides a replicable planning paradigm for coastal regions to assume greater emission-reduction responsibilities and meet climate targets. Offshore carbon capture projects in southern China can break even before 2040, with transport distance as a key driver. These insights are based on geological assessment, phased planning, and technoeconomic analysis and GIS spatial analysis.