Alternative Energy Japan - Micro & Mini Hydroelectric

Japan's Daily Yomiuri reports that small-scale hydroelectric power generation is quietly becoming a big thing, with small output generators being established near mountain streams or on public water supplies.

On Yakushima island, a microhydroelectric power facility was installed by the Kamiyakucho municipal government at Shirotani-Unsuikyo gorge, a densely wooded mountain area.

Water flows through two 524-meter-long pipes with a diameter of 7.5 centimeters, dropping 76 meters and turning a small turbine with a diameter of 26 centimeters. The system generates 4 kilowatts of electricity, which supplies energy for a mountain office and toilets for tourists.

The New Energy and Industrial Technology Development Organization (NEDO) defines microhydroelectric power facilities as having a maximum output of 100 kilowatts or less, while those with a maximum output of up to 1,000 kilowatts are called mini-hydroelectric power facilities.

Small-scale hydroelectric power plants have long been regarded as suitable for producing electricity in mountainous areas, but now they are increasingly used in cities as well.

In April, the Kawasaki City waterworks department and Japan Natural Energy Co. jointly installed a microhydroelectric power generator on a water pipe between a water purification plant and a distribution reservoir in the city. The site exploits a 38-meter difference in altitude between the two water facilities to distribute tap water.

A pipe between the two facilities had a bypass attached on which a power generator with an output of 170 kilowatts was installed. The electricity generated on the site is sold to Tokyo Electric Power Co. Since the system is installed on a pipe used for water for domestic use--water of fairly reliable quality--it generates electricity and is virtually maintenance free.

The company is currently building three similar facilities in Gunma and other prefectures in Japan and is hoping to construct 30 such facilities in the next three years.

Small-scale hydroelectric power generation is possible without seriously damaging the environment. For example, it can be done by using the natural features of a mountain stream or flow from an existing dam. NEDO decided to subsidize 28 small-to-medium scale hydroelectric power facilities. A Kansai region waterworks department managed to save millions of yen on its electricity bill by using hydro-power generated electricity to pump water to its customers.

The geological and geographical features of Japan mean there are countless sites where hydroelectric energy could be harnessed.

Daily Yomiuri on Japanese Small Scale Hydroelectric Power Generation