Greenwashing? | Hydrogen-based ammonia now being burned with coal at Japanese power plant

Move has been criticised as an expensive, dirty option that would do little more than extend the lifetimes of highly polluting coal-fired power stations

The 4.1GW Hekinan coal-fired power plant, one of the most polluting in the world.Photo: Wikimedia

Leigh Collins

Editor, Hydrogen Insight

Japan’s largest electricity generator JERA has begun co-firing ammonia at its 4.1GW Hekinan coal-fired power plant in Japan as part of the world’s first commercial demonstration project of the technology.

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The NH₃ — made using grey hydrogen derived from fossil gas — is now being burned with coal at the 1GW unit 4 of the power station as part of an emissions-reduction strategy that experts have described as very expensive and potentially worse than burning coal directly.

“By establishing the technology for ammonia substitution, JERA will offer a clean energy supply platform that combines renewable energy with low-carbon thermal power, contributing to the healthy growth and development of Asia and the world,” the company says in a statement.

But such claims have previously been debunked, with research house BloombergNEF (BNEF) pointing out in a 2022 study that JERA's plans for 50% co-firing of the cheapest possible green ammonia (made with renewable energy) at coal plants in Japan would be significantly more expensive than using even the costliest forms of renewable energy directly, such as offshore wind and battery-backed onshore wind and solar.

It would also be more expensive and more polluting than running unabated gas-fired power plants, according to BNEF.

Using renewable energy to produce green hydrogen — and to drive the energy-intensive Haber-Bosch process that combines H₂ with nitrogen in the air to make ammonia — means that as little as 18% of the original renewable energy content would be utilised when it is burned at a coal power station, inevitably making it an expensive option.

Data analytics non-profit organization Transition Zero told Hydrogen Insight last year that ammonia co-firing could be used as an incentive to keep coal plants on line for longer — and allowing them to burn 100% coal when ammonia is found to be too expensive to burn.

“Japan’s industrial heavyweights are peddling the false narrative that ammonia-coal co-firing is an effective emissions reductions strategy for Southeast Asian countries,” Transition Zero wrote last year. “Co-firing ammonia could even be worse for the environment than burning unabated coal due to the very high embedded upstream [methane] emissions [when using fossil gas to make grey ammonia] and energy losses from production of hydrogen and NH₃.”

In addition, burning ammonia in air can produce nitrous oxide (N₂O), which is 273 times more powerful a greenhouse gas than carbon dioxide.

JERA says that it seeks to “establish technology for the use of fuel ammonia in thermal power generation with a view toward mainstreaming in society by March 2025”.

It adds that its burner supplier and demonstration project partner IHI will “apply the knowledges gained through the project to establish technology for high-ratio combustion of 50% ammonia or more at thermal power plants and to develop burners for 100% ammonia combustion, deploying the results of the demonstration testing to other thermal power plants in Japan and overseas will contribute to global decarbonization through fuel ammonia”.

The pilot had been scheduled to start last week, but was delayed due to the need for additional safety testing, and will now run until mid- to late June.

JERA signed a sales contract in June last year with fellow Japanese firm Mitsui for the supply of grey ammonia used during the trial.

However, the Japanese power generator has also signed memoranda of understanding with Yara and CF Industries for the supply of 500,000 tonnes a year each of blue or green ammonia from 2027, when it plans to extend the 20% co-firing from a trial to commercial operations.

JERA also plans to demonstrate 50% ammonia co-firing by March 2029, for which the Japanese government has already allocated ¥27.9bn ($187m) in subsidies.

Greenwashing? | Hydrogen-based ammonia now being burned with coal at Japanese power plant

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