Carbon dioxide is primarily transported by pipelines or ships. While pipelines are more cost-effective over short distances, for longer distances over 300 km, ships are seen as delivering greater economic benefits. As a result, several Japanese and European projects are currently underway will use LCO₂ carriers to transport CO₂ for storage.

Mitsubishi Shipbuilding has extensive experience in the design and construction of liquefied gas carriers such as LNG and LPG carriers. Leveraging the low-pressure liquefied gas handling technologies cultivated through these projects, we are developing LCO₂ cargo handling technology, which we offer as engineering solutions or products.

Mitsubishi Shipbuilding is advancing technology development aimed at realizing large-scale LCO₂ tanks. In the manufacturing of large LCO₂ tanks, post-weld heat treatment (PWHT) is typically required for welded joints. However, only a limited number of heat treatment furnaces can accommodate large tanks, making this process a major obstacle to tank upscaling and mass production. To address this challenge, Mitsubishi Shipbuilding has conducted a weld integrity assessment known as Engineering Critical Assessment (ECA). Based on the results of this assessment, we have obtained General Design Approval (GDA) from Nippon Kaiji Kyokai (ClassNK) for a technology that omits PWHT. Through the development of such new technologies, we ensure the safety of large-scale LCO₂ tanks while balancing cost-effectiveness and productivity, thereby contributing to the reduction of LCO₂ transportation costs.

To enable the scaling up of tanks, we are developing low-pressure LCO₂ handling technology that allows transportation under low-pressure conditions instead of the conventional medium-pressure conditions. Under low-pressure conditions, LCO₂ is at conditions close to its triple point, increasing the possibility of solidification (dry ice formation) and two-phase flow within the piping during liquid transfer. However, through various validations, we have been developing technologies to prevent and avoid the effects caused by solidification and two-phase flow.

Approval in Principle (AiP) has been granted by classification societies for the low-pressure liquefied CO₂ carrier designs of 50,000 m³ and 23,000 m³ capacities, for which Mitsubishi Shipbuilding took the lead in basic design. These approvals recognize that the designs meet technical requirements and safety standards. This AiP was acquired jointly with Kawasaki Kisen Kaisha, Ltd., Mitsui O.S.K. Lines, Ltd., Nihon Shipyard Co., Ltd., Nippon Yusen Kabushiki Kaisha, Mitsui & Co., Ltd., and Mitsubishi Corporation. Additionally, we have completed the basic design of a comparatively smaller low-pressure liquefied CO₂ carrier intended for domestic coastal transportation of CO₂, and jointly with Nippon Gas Line Co., Ltd. (NGL), obtained Approval in Principle from the classification society. Through such collaborations with related domestic and international companies, we are actively promoting the development of LCO₂ carriers and the establishment of the CCS value chain.