Idemitsu Kosan, ENEOS and Hokkaido Electric Power have agreed to study building what they describe as Japan's largest water electrolysis plant, in Tomakomai on Hokkaido. The target is more than 10,000 tons of green hydrogen a year by 2030. No money has changed hands and no investment decision has been taken. What the three companies have agreed on is a problem: Hokkaido makes more renewable power than it can use.
Key takeaways
- Idemitsu Kosan, ENEOS and Hokkaido Electric Power announced on 20 February 2024 a partnership to study a domestically produced green hydrogen supply chain in the western Tomakomai area of Hokkaido, Japan.
- The Tomakomai study targets construction by 2030 of what the partners describe as Japan's largest water electrolysis plant, capable of producing more than 10,000 tons of green hydrogen a year, with Leap recording 100 MW of electrolysis capacity and a target operating date of June 2030.
- Hydrogen from the Tomakomai plant would be supplied by pipeline to Idemitsu Kosan's refinery in the region, for synthetic fuels, and to local factories.
- A survey in western Hokkaido identified total demand of 70,000 tons of hydrogen to replace fossil fuels across factory processes, power generation, heat and mobility, about seven times the planned Tomakomai output.
- Enerdatics tracks 38 hydrogen projects in Japan, of which 12 disclose a capacity; at 100 MW, Tomakomai is the largest, ahead of a 40 MW research facility operated by Mitsubishi Heavy Industries.
Why build an electrolyser in Hokkaido?
Because Hokkaido has more renewable energy potential than it has demand for electricity. The partners say so directly: the island faces challenges from limited electricity demand and surplus energy. Renewable generation built there risks having too few local customers.
An electrolyser turns electricity into hydrogen by splitting water. Placed in Hokkaido, it becomes a consumer of last resort for surplus power. The partners describe the plant as a regulating power source, meaning it can run harder when there is excess renewable output and back off when there is not. That helps integrate more wind and solar into the island's electricity market.
Leap's project record adds that the hydrogen would be produced using abundant renewable sources, particularly offshore wind power in Hokkaido. The electrolyser is a way of creating local demand for generation that would otherwise struggle to find a buyer.
Who does what in the partnership?
Each partner brings a different part of the chain. Hokkaido Electric Power is the regional utility, with access to the island's renewable power. Idemitsu Kosan has the refinery in the region, which Leap's record names as the offtaker for the hydrogen. ENEOS says it is focused on building CO2-free hydrogen supply chains both in Japan and internationally.
Each partner frames the project in its own terms. Idemitsu ties it to a 2050 vision of a carbon-neutral society. ENEOS links it to its long-term vision of a stable energy supply. Hokkaido Electric Power targets carbon neutrality by 2050 and says it is working with various stakeholders on a hydrogen supply chain using the island's renewable resources.
The pipeline is the practical link. Rather than compress or liquefy the hydrogen and ship it elsewhere, the plan is to pipe it a short distance to the refinery and local factories. That keeps the hydrogen close to where it is made and to the users the survey identified.
How big is 10,000 tons a year?
Small against the demand the partners have measured, but large for Japan. A survey in western Hokkaido found demand of 70,000 tons a year to convert from fossil fuels to hydrogen across industrial uses. The Tomakomai plant would cover about one seventh of that.
The 100 MW figure in Leap's project record gives the scale in power terms. More than 10,000 tons a year from 100 MW of electrolysis works out at about 100 tons of hydrogen for every megawatt of capacity each year.
Enerdatics' data shows how far ahead of the rest of Japan's hydrogen pipeline that puts Tomakomai. Enerdatics tracks 38 hydrogen projects in Japan. Only 12 disclose a capacity. Tomakomai, at 100 MW, is the largest. The next largest is a 40 MW research facility operated by Mitsubishi Heavy Industries at Takasago, followed by a 16 MW plant operated by Suntory at Hakushu. Most of the rest are below 5 MW. Enerdatics also records only three hydrogen partnerships or acquisitions in Japan in 2023 and 2024, and none disclosed a value.
What does the partnership signal for hydrogen in Japan?
It signals that Japan's oil refiners are treating domestic green hydrogen as a real supply option, alongside imports. The partners link the initiative to the government's Basic Hydrogen Strategy, which, as they describe it, emphasises domestic production and supply.
ENEOS is pursuing both routes at once. Three months before Tomakomai, it signed a memorandum of understanding with Air Liquide covering the whole low-carbon hydrogen value chain in Japan, from production to refuelling stations. In January 2024 it took a stake in a US hydrogen developer, as Enerdatics explained in ENEOS backing MVCE Gulf Coast to test 'cost-competitive' hydrogen for Japan. Tomakomai is the domestic counterpart: smaller, closer to its customers and tied to a local surplus of renewable power.
Hokkaido Electric Power is not limited to one hydrogen project either. Leap also records it as a partner in a separate Hokkaido green hydrogen plant with Green Power Investment, Nippon Steel and Air Water. That puts the island's utility inside more than one electrolyser plan.
The caution is in the wording. This is a study, with a target date six years out. Until a final investment decision is taken, Tomakomai is a plan for Japan's largest electrolyser, not a project under construction.
Frequently asked questions
What did Idemitsu Kosan, ENEOS and Hokkaido Electric Power agree? On 20 February 2024 they announced a partnership to study a green hydrogen supply chain in western Tomakomai, Hokkaido, built around a water electrolysis plant targeted for 2030.
How much hydrogen would the Tomakomai plant produce? More than 10,000 tons of green hydrogen a year. Leap records the plant at 100 MW of electrolysis capacity with a target operating date of June 2030.
Where would the hydrogen go? By pipeline to Idemitsu Kosan's refinery in the region, for synthetic fuels, and to local factories.
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