Advances in subsea carbon dioxide utilization and storage

Decisive steps in innovation and competitiveness are needed to meet global greenhouse gas emissions and climate goals. As an effective method for reducing carbon emissions, carbon dioxide (CO2) storage and utilization on the seabed enable the transport of captured CO2 via pipelines or ships to permanent storage sites, such as saline aquifers or depleted oil and gas reservoirs in subsea sediments, or by injecting CO2 for the replacement and displacement of subsea resources (oil, gas, gas hydrates, etc.). Subsea CO2 utilization and storage (SCUS) involves several research hotspots worldwide, including international and local laws and regulations, security, economics, environmental impact, and public acceptance. Its current research and engineering progress are also of great interest. In addition, the vigorous implementation of the energy transition and the rapid development of renewable energy sources globally have resulted in significant advancements in SCUS. This paper provides an overview of carbon dioxide storage and utilization mechanism in the seabed, analyzes key technical and economic issues, and summarizes existing research on safety risks, monitoring technologies, and investment and operating cost control to identify remaining knowledge gaps. This is followed by an overview of global engineering practice to update on current progress. Finally, combined with the actualities of China, the potential and trend of China's seabed carbon storage and utilization are summarized. This review demonstrates the enormous development prospects for seabed carbon storage and utilization, although some risks remain including leakage and contamination, with which innovation in monitoring technologies and the self-sealing effect of gas hydrate, safe subsea utilization and storage of CO2 can be achieved. Additionally, considering the development of renewable energy and the demand for large-scale energy storage, hydrogen, ammonia, or other energy carriers and carbon dioxide storage and utilization can be coupled into an industrial chain to form an economically competitive carbon geological storage mode.