Tuesday, October 20, 2015

Japan: Binary Geothermal Plant at Obama Onsen

Japanese Town Ventures Into Clean Energy (National Geographic)

On the foothills of the Mt. Unzen Volcano, the Nagasaki Prefectural town of Obama Onsen,  which literally means “Small Beach Hot Springs” in Japanese, is harnessing the power of the earth. In the town famous for its relaxing therapeutic spas and some of the hottest natural springs in Japan, the local people have come together to start their own renewable energy initiative.

To supplement the loss of nuclear power, the use of oil, natural gas and solar has since increased to stabilize the energy supply. However, according to reports only 2 percent of Japan’s geothermal resources are used to generate electricity.

The people of Obama Onsen believe that there is another way to produce clean geothermal energy in a way that is rarely done in Japan.  Prior to this new initiative, the hot springs in Obama Onsen were noted to waste 70 percent of their famously hot water. The 180 kW Obama Onsen Energy Plant uses the excess heat from natural hot springs to generate electricity. The concept has the power plant run and funded entirely by collaborating with local people and a company, Koyo Denki Co.

The energy plant uses 100℃ (boiling) spring water in a heat exchanger. The hot water evaporates the fluorine into steam that turns the turbine. Sea water is used to cool the vapor back into liquid for the binary process to begin again.

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