BAKU, Azerbaijan, Feb. 24. Japan’s INPEX Corporation and Osaka Gas Co., Ltd. have begun demonstration operations at what they describe as a world’s largest-class methanation test facility, advancing efforts to commercialize carbon-neutral city gas, Trend reports via INPEX.
The companies said the move follows the completion of construction and trial runs of the facility, part of a joint technology development project aimed at the practical deployment of a CO₂ methanation system.
The initiative was launched by INPEX in 2021 after being selected for a subsidy program by Japan’s New Energy and Industrial Technology Development Organization (NEDO). Construction of the facility began in 2023.
The plant has a processing capacity of 400 Nm³-CO₂ per hour — equivalent to the annual gas consumption of roughly 10,000 households. Synthetic methane (e-methane) produced at the site was successfully injected into a natural gas pipeline on Feb. 20, the companies said.
Located at the Koshijihara Plant within INPEX JAPAN’s Nagaoka Field Office in Niigata Prefecture, the facility uses captured CO₂ as feedstock to produce e-methane. During trial operations, the partners achieved their technical target of producing synthetic methane with a methane concentration of 96%.
Going forward, part of the output will continue to be injected into INPEX JAPAN’s natural gas pipeline via the Koshijihara Plant, while demonstration activities will prioritize safety and environmental performance.
Under the partnership, INPEX is responsible for overall project management and plant operations, as well as building expertise in CO₂ methanation, scaling up the reaction system and assessing deployment potential in other regions.
Osaka Gas is leading development of the reaction process technology, leveraging its energy-efficient catalytic technologies and scale-up design expertise to further optimize equipment and processes.
The facility received certification as a clean gas production plant under the Clean Gas Certificate System supported by the Japan Gas Association on Jan. 27, 2026. The certification allows the environmental value of the synthetic methane to be issued as certificates following equivalent verification.
INPEX said in its Vision 2035 strategy, announced in February 2025, that it aims to advance low-carbon solutions centered on carbon capture and storage (CCS) and hydrogen as key growth pillars.
Meanwhile, the Daigas Group, parent of Osaka Gas, outlined in its “Energy Transition 2050” initiative plans to expand technologies and services supporting a decarbonized society.
Through the joint project, the companies aim to accelerate the early commercial deployment of carbon-neutral city gas produced via CO₂ methanation.