INPEX and Osaka Gas have started demonstration operations at a large CO2 methanation test facility in Nagaoka, Niigata Prefecture, aiming to advance carbon‑neutral city gas. The Nagaoka Methanation Demonstration Project has a capacity of 400 Nm3 of CO2 per hour, equivalent to the annual gas use of around 10,000 households, and successfully injected synthetic methane (e‑methane) into a natural gas pipeline for the first time on 20 February 2026.
The newly commissioned facility, which began construction began in 2023, and is supported by Japan’s NEDO program, uses CO2 captured from INPEX Japan’s Koshijihara Plant as feedstock which is then converted into methane using catalyst-powered hydrogenation reactors. Trial operations have already met a key technical goal of producing synthetic methane with a methane concentration of 96%, confirming that the methanation system can produce pipeline‑grade gas.
INPEX is managing overall project operations, focusing on building expertise in CO2 methanation, scaling up the reaction system and assessing where the technology can be deployed commercially. Osaka Gas is leading development of the reaction process and catalytic technology, using its know‑how to improve energy efficiency and support future scale‑up of equipment and processes.
The test facility has been certified under Japan’s Clean Gas Certificate System, which is supported by the Japan Gas Association, meaning the environmental value of the e‑methane can be issued as certificates once it is recognised as “clean gas equivalent.”
The project supports INPEX’s “Vision 2035” strategy to advance low‑carbon solutions such as CCS and hydrogen, and Osaka Gas’s “Energy Transition 2050” roadmap to help deliver technologies and services that support a decarbonised society.
Both companies see this work as a step toward early, real‑world deployment of carbon‑neutral city gas based on CO2 methanation.
