No. 71: Prospect of natural energy in Japan – Geothermal generation (July 1, 2011)

Japan is a country of volcanoes. It has the world’s third largest geothermal resources following Indonesia and the U.S., and it has excellent technology for geothermal generation because it has 70% share in the geothermal generation turbine market. If Japan can use all its geothermal resources for generation, it will have a generation capacity close to 24 million kW that is equivalent to the same output by 23 nuclear plants. Nonetheless, Japan’s current geothermal capacity stays at 0.5 million kW which is the 8th largest in the world. Why? The answer is simple. Nearly 80% of geothermal energy sources are located inside national parks.

In 1972, two Japanese government agencies concerned reached an agreement not to promote the development of geothermal energy sources inside national parks for the time being. The phrase of “for the time being” means 40 years for Japanese government agencies. The environment Agency, one of the two agencies, decided to deregulate the development inside the national parks last June. It allowed developers to dig a hole outside of a national park toward inside it at an angle. Tohoku Electric Power started a project to dig a hole in this way at its Sumikawa Geothermal Power Plant in Akita Prefecture. If you dig a hole outside the national park at an angle toward inside it for 2.5 km, you can get inside the national park in about 100-200 m to reach a heat source. The heat source inside is higher than 300 degrees C that is enough for a highly efficient heat source.

According to the Environment Agency, possible thermal generation capacity from outside heat sources alone is 2.2 million kW, but it will increase to 6.4 million kW if digging at an angle toward inside is allowed for a distance less than 1.5 km. If the distance is doubled, it will be 10.3 million kW that is equivalent to the power generated by 10 nuclear power plants, and 43% of Japan’s total heat sources for geothermal generation can be utilized.

Hot springs generation is scheduled to be made practicable pretty soon. Geothermal Energy Research & Development will start the substantiative experiment in a hot spring coming November. The system heats ammonia water using hot spring water and runs the turbine using the resulting steam. A system of hot springs generation with a generation capacity of 50 kW can secure the same output by the photovoltaic generation of 100 households.

A high operating rate also characterizes geothermal generation. Photovoltaic generation has an operating rate of 12% and wind generation 20%, but geothermal generation has an operating rate of more than 90%. However, the demonstration equipment for hot springs generation is 100 million yen. As always, cost is the greatest obstacle for the spread.