A climate activist group is seeking to stop Japan’s biggest utility from using advertisements that include phrases such as “zero-emissions thermal power.”

Kiko Network filed a petition calling on the nation’s advertising regulator, the Japan Advertising Review Organization, to prevent Jera Co. from using publicity materials that say its power generation won’t produce carbon dioxide. The advertisements may mislead consumers as Jera fails to mention that the ammonia the utility plans to use would emit the greenhouse gas during its production, the campaigner said on Friday.

Japan’s government and power producers such as Jera are looking to co-firing technology, which uses ammonia and hydrogen in existing coal and gas-fueled plants, to reach targets for carbon neutrality by 2050. While the resource-scant nation has argued the strategy is necessary to maintain energy security and power grid stability, critics argue the policy is expensive with little benefit toward reducing emissions.

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Jera is aware of the petition and will respond as needed, a company spokesperson said. The utility, a venture between Tokyo Electric Power Co. and Chubu Electric Power Co., plans to start demonstration tests using ammonia, which theoretically produces only nitrogen and water when burned, at a power station by end-March.