Waterwheels in Yamanashi Prefecture are receiving renewed interest as miniature, eco-friendly hydropower generators against the backdrop of global warming.
The heart of the small-scale hydropower generation system is the waterwheel turbines, which pump out up to around 2,000 kilowatts of electricity. According to the Agency for Natural Resources and Energy (ANRE), as of 2009 such small hydro generators were being operated in 474 places across the country.
Until the 1970s, waterwheels for private use were a common sight in brooks and irrigation ditches across the country, but many of them were removed as major power companies improved electrical grids.
Small-scale hydropower generation is attracting a great deal of attention as it requires little alteration to local geography to install generators and emits almost no carbon dioxide thanks to its high energy conversion efficiency. In addition, a system that can generate electric power without requiring large volumes of flowing water and great differences in water elevations has been newly developed.
In 2005 the municipal government of Tsuru, Yamanashi Prefecture installed its first waterwheel — measuring six meters in diameter and two meters in width — in a brook by its office, ahead of other local governments in the country. The city has a plentiful supply of underground water from Mount Fuji. The maximum output of 20 kilowatts produced by the waterwheel is used in the city office building on workdays and is provided to a utility firm at night and on holidays.
According to Tsuru City officials, they have so far received more than 4,000 inspection visits to their waterwheels from other local governments, electricity establishments, the Japan Agricultural Cooperatives and civic groups.
Whether or not installing waterwheels can earn back the cost of the city’s investment had previously been called into question, but it later became a state-supported project. In 2006 ANRE issued subsidies for two waterwheel installations for the first time, and the number of such subsidized cases increased to 19 by 2009.
Moreover, a local electricity firm in Uozu, Toyama Prefecture plans to build a small hydropower facility that generates a maximum output of 1,000 kilowatts using an erosion-control dam, calling on citizens in September this year to invest in the roughly 800-million-yen project. According to an investment house connected to the project, it received some 270 citizen applications and collected approximately 300 million yen in a month.
Meanwhile, Tetsunari Iida, executive director at the nonprofit organization Institute for Sustainable Energy Policies in Tokyo, points out that if a system in which power companies buy all small-scale hydropower-generated electricity at fixed prices is enshrined in law, such projects won’t have to rely on central government subsidies.
“It’s important to make it work as an eco-friendly and profitable industry,” says Iida.
