Exploring the CCUS potential of China's coastal areas based on a source-to-offshore sink matching model

Coastal areas, which are central to China's economy and contribute significantly to its emissions, face substantial challenges in achieving near-zero emissions. Given the high concentration of fossil fuel emission sources in these regions, carbon capture, utilization, and storage (CCUS) offers a promising solution for achieving deep emission reductions without early infrastructure retirement, particularly in coastal zones where subsea geological formations provide ideal conditions for CO₂ storage. Focusing on industrial emission reductions, we develop a high-resolution source-to-offshore sink matching optimization model to evaluate the CCUS potential in China's coastal regions, with particular emphasis on the cost differentials between onshore and offshore deployment while establishing practical land-sea source-sink connections. The results indicate that offshore basins can store up to 1.91 Gt CO₂ annually from coastal regions. Key factors influencing cost-efficient deployment include CO₂ transport distance and retrofit timing. Extending the allowable transport distance from 150 km to 300 km almost doubles the carbon storage capacity, while postponing retrofitting to 2035 would reduce the potential by approximately 50 % compared with 2030 scenario. Across all scenarios, the abatement cost curves stabilize at around $40–50/t CO₂, primarily from coal-fired power plants (66%–76%) and steel plants (20%–30%). Offshore basins are identified as cost-effective storage options, especially for provinces like Shandong and Jiangsu, which have high offshore CCUS potential (over 240 Mt/a) and relatively low abatement costs (approximately $50/t). Overall, accelerating offshore storage development and prioritizing early demonstration projects are crucial for deep decarbonization of fossil energy industries in coastal areas, especially in southern Chinese coastal provinces with limited onshore storage capacity.