Mibugawa Power Company has eight hydropower plants in Nagano, a mountainous prefecture located northwest of Tokyo. The region, surrounded by the magnificent Japanese Alps, boasts picturesque landscapes and is among the top tourist destinations in Japan. 

The mention of hydroelectricity often makes people think of damming up a river with a massive concrete structure, but all the eight power plants of Mibugawa are of small hydro type; they generate electricity utilizing the energy of falling water. The water is supplied either from an irrigation canal or a natural stream and it flows rapidly down a steep hill through a penstock into the water-turbine generator, which converts the motion into electrical energy. The used water goes back to its sources.

Small hydropower requires a rich, dependable flow of water as well as a steep incline for the water to fall. When such a place is proposed, the project development team visits the candidate site to study its geographical features and water supply. To be safe and successful, since they are exploring nature, being prepared is of utmost importance. In fact, the team members often encounter bears or boars during their expedition, and they carry a bear bell and use a safety rope to descend cliffs.

Tateshina Power plant 2 (output power: 141 kW), one of Mibugawa Power Company’s eight power plants in Nagano, has provided electricity to the local community since 2014. Its annual production is in proportion with the aggregate annual consumption of the local 250 households, many of whom are rice growers. The power plant takes water from their irrigation canal that stretches 10 km across the area. The water flows into the generator unit through the penstock; the “head of water,” the vertical distance between the intake and the turbine, is 33.6 m. 

It goes without saying that the company needs the support of local farmers when it comes to developing a new power plant within their agricultural water-supply system. Until all farmers in the area are convinced that the impact on the environment will be minimal, the development team will continue to explain that a small hydropower plant only requires a compact facility.

Japan relies heavily on imported fossil fuels to meet its energy demands; its self-sufficiency rate remains low at 6%. Nonetheless, electricity production from renewable energy sources has not sufficiently prevailed because of its high costs. Excluding large-scale hydropower, it accounts for just 3.2% of the nation’s total electricity production. In 2012, the government introduced a feed-in tariff to promote renewable energy. Under this scheme, electric utility companies offer producers fixed prices based on fixed-term contracts to purchase electricity generated from renewable energy sources. Their purchasing costs are covered by the surcharge that all consumers, including private households, pay. 

All nuclear reactors in Japan were shut down in 2011 in the aftermath of the massive earthquake and tsunami, which devastated the eastern region of Japan. This resulted in a nationwide electricity crisis and underscored the need to accelerate investments in the development of alternative energy sources. 

In response to these events, Marubeni boosted its Japanese power business by speeding up projects to create power plants: small hydro, solar, wind, and biomass. Out of all of the power plants the company currently owns, 43% use renewable energy sources to generate electricity (as of October 2017). 

In July 2017, Marubeni commenced commercial operation of a biomass power plant owned by its subsidiary company, Tsuruga Green Power, which is based in Tsuruga, a city in the southwest of Fukui. In biomass power, electricity is generated by burning fuels derived from organic materials such as wood or animal waste. Tsuruga Green Power uses primarily woodchips and has a total capacity of 37 megawatts, equivalent to the annual aggregate consumption of electricity by 70,000 households.

Tsuruga Green Power is situated near the city center, surrounded by retail stores, condominiums, and schools. When the construction project was initially announced, some residents in the local community expressed their concerns over noise and air pollution. Others worried that if the plant took up a large volume of groundwater, which they use for daily living, water would be scarce. 

“Since the design phase of our plant, we have incorporated voices of people in the local community as much as possible. We are trying to be mindful of their needs,” says Shuki Sakaguchi, general manager of the plant. The height of the stack is 80 m while in fact only 50 m was sufficient in terms of air-pollution control. The boiler is enclosed with sound-blocking panels. The cooling system utilizes industrial wastewater, so groundwater does not need to be pumped up. The plant is also committed to minimizing the impact of its fuel transportation on people’s daily lives. Transport trucks go back and forth between the plant and the port where woodchips are being stockpiled, however during the hours that children walk to and from school, the number of trucks on the road is reduced.

The key to maintaining the stable operation of a biomass power plant is its owner’s ability to procure fuels. At Tsuruga Green Power’s plant, 280,000 tons of woodchips per year are needed to produce electricity, and they are imported from overseas by Marubeni’s Forest Products Division. “It’s our strength as a sogo shosha (general trading company) that create this synergy,” says Shota Anzai, a young member of Marubeni’s Japanese power business department. He joined the company only four years ago, but he has been engaged in this biomass business since the project was launched. He is currently based in Tsuruga dealing with all aspects of the plant management. “I feel a strong sense of pride that our plant is part of the infrastructure that helps ensure the quality of life of people,” Anzai says.