By Niu Song, CCS Shanghai Rules & Research Institute; Li Sen, CCS Offshore Engineering Technology Center

China Classification Society (CCS) has been closely monitoring the development trends of green emission reduction technologies in the shipping industry, tracking the pain points of industry development, and collaborating with the industry to seek solutions to safeguard the safe and sustainable development of the sector. Existing greenhouse gas emission reduction technologies are proving insufficient to meet future regulatory requirements. The current consensus regarding the realization of greenhouse gas emission reduction involves two main approaches: overall ship optimization and marine power transformation.

Overall ship optimization primarily focuses on four aspects: first, reducing resistance through hull form optimization; second, improving propulsion and fuel efficiency through propulsion system optimization; third, reducing energy consumption by lowering ship mass through the application of new materials; and fourth, reducing ship energy loss through the installation of energy-saving equipment. However, the potential for improvement with these traditional carbon emission reduction technologies is currently very limited, making it difficult to meet the net-zero emission targets set by the IMO for around 2050. Marine power transformation mainly involves the adoption of low-carbon fuels, but their application still requires a long period of exploration. Therefore, there is an urgent need to conduct research on key technologies for CO2 emission reduction under the existing energy structure and make relevant technological reserves to cope with increasingly stringent carbon emission regulations.

Meanwhile, Carbon Capture and Storage (CCS) technology is recognized as a crucial potential means for achieving large-scale CO2 emission reduction in the future, possessing broad application prospects in this field. To ensure the industry can apply this technology in a safer and more standardized manner, CCS, in collaboration with the industry, has actively conducted research on key technologies for shipborne carbon capture. CCS has successively compiled and released guidelines such as the Guidelines for Carbon Capture Systems on Ships, Guidelines for Survey of Shipborne Carbon Capture and Storage Systems, and Guidelines for Shipborne Liquid Carbon Dioxide Loading and Discharging Operations, aiming to provide strong technical support for the green and low-carbon development of the shipping industry.

The Guidelines for Carbon Capture Systems on Ships came into effect on January 1, 2024. The Guidelines primarily cover additional class notations, design and arrangement, CO2 absorption and desorption, decarbonant supply systems, CO2 compression and liquefaction, CO2 storage and unloading, control, monitoring and safety systems, survey, and the pre-installation of shipborne carbon capture systems. As an important supplement to CCS's Green Ship Rules system, the Guidelines have been successfully applied to the construction of the 82,000 DWT bulk carrier newbuilding "Shandong Xinsheng" (equipped with an OCCS) and the retrofitting of the in-service vessel "Yuedian 56" (equipped with an OCCS). This provides solid technical support for classification surveys and technical services related to green emission reduction, while also offering a demonstration for the engineering application of carbon capture technology in both new buildings and existing ships.

The Guidelines for Survey of Shipborne Carbon Capture and Storage Systems officially came into effect on November 1, 2023. These Guidelines are primarily applicable for guiding the approval and survey of shipborne carbon capture system products, providing technical support for the design, manufacturing, and survey of product manufacturers. They will play a positive role in promoting the research, development, and popularization of OCCS products.

The Guidelines for Shipborne Liquid Carbon Dioxide Loading and Discharging Operations (2025) came into effect on July 1, 2025. With the gradual improvement of OCCS technology and the commissioning of demonstration vessels, the construction of the backend industrial chain—including the unloading, storage, and utilization of captured CO2—has become increasingly urgent. The safe unloading of CO2 captured on board and its transportation to the destination is a critical step in the application of marine carbon capture technology. To improve storage and transportation efficiency and reduce operational costs, CO2 captured on ships is primarily stored in a liquid state. Liquid CO2 possesses characteristics such as high density, being colorless and odorless, having a triple point, and being asphyxiant. Its loading and unloading operations involve risks such as cryogenic freezing, solidification and blockage, overpressure explosion, and asphyxiation. The Guidelines cover aspects such as loading and unloading equipment measures, piping arrangements, pressure control, protective equipment, operational procedures, and emergency response measures. They encompass full-scenario operational modes including ship-to-ship, ship-to-shore, ship-to-tanker truck, and ship-to-barge, clarifying technical requirements and operational procedures for different scenarios. While standardizing operational methods and improving efficiency, the Guidelines aim to minimize safety accidents during shipborne liquid CO2 handling and ensure the smooth progress of operations.

In the offshore engineering sector, CCS released the Guidelines for Survey of Offshore Oil and Gas Carbon Capture, Utilization, and Storage Systems (2023), which came into effect on June 1, 2023. Based on the actual needs of China's offshore oil and gas development, CCS actively initiated research projects on offshore carbon capture technology and formed a project team for these Guidelines. After years of dedicated research focusing on the efficient development, green, and low-carbon aspects of marine resources, CCS closely monitored cutting-edge technologies and key risk points in offshore carbon capture. Through in-depth research into current technological developments and industry experience, as well as studies on relevant domestic and international standards, and combined with review and survey experience from projects such as the Enping 15-1 CO2 reinjection and the Zhuhai Gaolan terminal CO2 recovery and utilization, the compilation of technical guideline for offshore oil and gas carbon capture was completed. These Guidelines will instruct the industry in the design, construction, and certification of offshore oil and gas CCUS systems, further improving the CCS technical rules system and enhancing dual-carbon technical service capabilities.

Today, climate change has become a major global challenge facing humanity. As a bottom-line technical option for China to achieve carbon neutrality by 2060, carbon capture technology is a key technical pathway to address climate change, achieve large-scale rapid emission reduction, and move towards carbon neutrality. For the current period and some time to come, fossil energy will remain an important component of the energy structure. Strengthening the R&D and application of offshore oil and gas carbon capture technology can effectively reduce carbon emissions from offshore oil and gas development, promote the clean utilization of fossil energy.

In the future, CCS will continue to closely monitor the development trends of green emission reduction technologies in shipping, actively conduct relevant technical research in collaboration with the industry, and respond proactively to market demands. By continuously launching technical and standard service products, CCS will contribute to the green, low-carbon, and high-quality development of the shipping and shipbuilding industries.