A Japanese consortium is forging ahead with a new geothermal project in the mountainous northern Akita Prefecture on the nation’s main island Honshu.

The consortium of Inpex, Mitsui Oil Exploration Company (Moeco) and Idemitsu Kosan have decided to start construction of the 14,990-kilowatt geothermal Katatsumuri Yama power plant halfway up Katatsumuri Yama mountain in the Oyasu District. The facility is scheduled to start commercial operations in March 2027.

The double-flash method geothermal power plant will be operated by Oyasu Geothermal, a company financed by the trio of Japanese players, which was set up in September 2018.

Double flash geothermal power plants produce a higher power output than single flash geothermal power plants but at a higher cost.

The dual flash method is more expensive than single flash because it requires more piping, a second separator, and low and high-pressure steam turbines.

Since 2011, Inpex, Moeco and Idemitsu Kosan have conducted studies on the potential commercialisation of geothermal projects including performing joint exploration of the subsurface resources in Oyasu District, verification of the scale of these resources and economic assessments.

These investigative studies were supported by subsidies from the quasi-governmental agency Japan Oil, Gas & Metals National Corporation (Jogmec).

Construction of the Katatsumuri Yama geothermal power plant is expected to be supported by a loan guarantee from Jogmec.

Power generated from the facility will be certified under the Feed-in Tariff System for Renewable Energy.

As the result of evaluation of data from production tests performed over three months in 2021, it is projected that long-term stable production of geothermal fluids (steam and hot water) equivalent to an output of approximately 15 megawatts will be possible.

“Moreover, with a design planned to be eco-friendly and harmonised with the surrounding scenery, the three companies will be undertaking the construction and operation of the Katatsumuri Yama power plant as a facility that will contribute to the region,” Inpex said.

It noted that expectations of geothermal energy have been growing “more and more” in recent years as a renewable energy source capable of delivering stable supplies of electricity unaffected by the weather.

“The three companies will continue to proactively promote the dissemination and expansion of the use of renewable energy to contribute to the realisation of energy security and a low-carbon society in Japan,” added Inpex.

The investment ratio in the consortium is Idemitsu Kosan and Inpex with 42.5% apiece and Moeco on 15%.

Jogmec stated priority mission is to secure a stable and affordable supply of energy and mineral resources “to maintain and strengthen Japan’s industrial base, economic prosperity and people’s everyday lives”.