INPEX Corporation and Osaka Gas have begun demonstration operations at a CO₂-methanation test facility which is expected to supply carbon-neutral city gas to approximately 10,000 households.

Construction of the facility, which has a capacity of 400 normal cubic metres (Nm³) of CO₂ per hour, making it the world’s largest, began in 2023 after INPEX was selected for a subsidy programme by the New Energy and Industrial Technology Development Organization (NEDO) of Japan. The resulting site consists of equipment for raw material supply, as well as methanation reactors and supporting utilities.

The carbon dioxide used as feedstock is captured from INPEX Corporation’s Koshijihara Plant in Niigata Prefecture. Catalyst-powered hydrogenation reactors then convert the CO₂ into synthetic methane.

INPEX says that through trial operations at the test facility, the technical development goal of producing synthetic methane with a methane concentration of 96% was successfully achieved. Synthetic methane produced at the site was successfully injected into a natural gas pipeline on February 20, 2026.

Going forward, a portion of the synthetic methane produced will be injected into INPEX Japan’s natural gas pipeline via the Koshijihara Plant. Concurrently, researchers will accumulate expertise in CO₂-methanation technology and operational experience with the equipment with a view to scaling up the reaction system, and studying its applicability for deployment in promising regions.

Demonstration operations at the test facility will prioritise safety and environmental considerations.