Phased Offshore CCUS Deployment Framework for Southern China’s High-Economic-Density Coastal Regions

Offshore carbon capture, utilization, and storage (CCUS) offers a viable path for high-emission, high-economic-density coastal regions to reach net-zero emissions. However, evaluating the cost-effectiveness and identifying optimal deployment timing remains challenging. Focusing on the most economically developed coastal region in southern China, this study quantifies CO ₂ emissions from 23 cities and assesses the storage potential of nearshore sedimentary basins. We develop a two-stage source–sink matching model that combines geologically constrained theoretical partitioning with GIS-enhanced minimum spanning tree optimization to identify an efficient CO ₂ transport network. Techno-economic analysis indicates offshore CCUS projects could begin turning a profit as early as 2037, with nearly all blocks profitable before 2040. Offshore CCUS can help high‑economic‑density coastal regions meet the 2°C target and even shoulder greater emission‑reduction responsibilities. The economics of large-scale CCUS clustering are highly sensitive to transport distance; if the distance exceeds 837 km, offshore CCUS will not be economically viable. Additionally, a regional mechanism for exchanging green electricity and storage capacity enables resource complementarities between wind-rich coastal regions and storage-capable regions, thereby more effectively advancing the Sustainable Development Goals. This study advances a generalizable approach to offshore CCUS planning for coastal economies.