Using low-temperature, low-pressure liquefied CO₂ to realize low-cost mass transportation: Demonstration test ship "EXCOOL" completed with expectations for social implementation in the future

The CO₂ transport demonstration test ship "EXCOOL" incorporates a marine cargo tank system for transporting carbon dioxide (CO₂) and was developed as part of the "Research, Development and Demonstration of CCUS Technology" commissioned by the New Energy and Industrial Technology Development Organization (NEDO). The manufacture of the demonstration test ship was completed, and a naming and delivery ceremony was held on November 28th. Nippon Gas Line (NGL) and the Engineering Advancement Association of Japan (ENAA) will conduct demonstration tests and the operation of the vessel commissioned by NEDO. After the test operation, the company will conduct a demonstration test of transporting liquefied CO₂.

CCUS (Carbon Dioxide Capture, Utilization and Storage) is a technology that separates, captures, utilizes and stores CO₂. It has attracted attention domestically and internationally as a means to significantly reduce CO₂ emitted from factories and thermal power plants into the atmosphere, leading to a decarbonized society. However, the sites of CO₂ emission and storage/utilization are often far apart. Establishing a technology to safely and inexpensively transport CO₂ in large quantities is a challenge for the widespread use of CCUS.

Against this background, to safely transport large quantities of CO₂ collected from facilities such as factories and thermal power plants to storage and utilization sites at low cost, NEDO aims to implement CCUS in society by 2030. ''Research, Development and Demonstration of CCUS Technology/Research, Development and Demonstration Projects on CO₂ Ship Transportation'' has been implemented since FY2021. The project will continue until FY2026.

In this project, technology to establish an integrated shipping system that includes CO₂ liquefaction, storage, cargo handling and ship transportation is being developed. A CO₂ cargo tank system for ships has also been developed and a success demonstration was completed using the CO₂ transport vessel "EXCOOL." This is a 72.0-meter-long, 12.5-meter-wide, 1,290-ton, 1,450-cubic-meter tank capacity demonstration test ship, completed at Mitsubishi Heavy Industries' Shimonoseki Shipyard & Machinery Works. The ship's name, "EXCOOL," is derived from the Japanese reading of EXCOOL, a word formed by combining EX and COOL. The CO₂ cargo tank system incorporated in the vessel can carry liquefied CO₂ at medium temperature and pressure (∼ -20 ℃, 2 MPa) to low temperature and pressure (∼ -50 ℃, 0.6 MPa). It can also carry LPG (liquefied petroleum gas).

In the demonstration test, cargo tanks will be loaded with liquefied CO₂ at various temperatures and pressures, and the CO₂ will be transported repeatedly mainly between the land bases in Maizuru City, Kyoto Prefecture and Tomakomai City, Hokkaido, which were constructed under the project. This will also allow for evaluation of the functionality of cargo handling facilities and storage tanks at land bases and identify the optimal CO₂ transport conditions for integrated shipboard transport, leading to the development of mass transport technology.

This is the first demonstration test in which liquefied CO₂ is transported by ship under low temperature and low-pressure conditions. Expectations are high for realizing low-cost technologies for transporting CO₂ in large quantities over long distances. Through this demonstration test, NEDO hopes to establish a technology for safe and low-cost mass transport of CO₂ by ship, aiming for social implementation of CCUS technology and contributing to the realization of carbon neutrality in 2050.