As visitors to any of Japan’s thousands of hot springs know, this country is sitting on a lot of very hot water.
So far though, little of it has been harnessed to produce energy. There are only 18 geothermal power plants in the country, and together they account for only 0.3 percent of Japan’s electricity production.
But some say that with Japan’s reliance on nuclear power plants coming into question, the country should harness more of its geothermal natural resource to provide clean, renewable energy.
“Japan has 10 percent of the world’s volcanic activity, so I think there is the possibility for more development,” said Kengo Aoyama, engineering section chief of the Yanaizu-Nishiyama geothermal plant, located here in an area filled with hot spring resorts.
Some 300 tons of steam and hot water emerge every hour here from 21 wells drilled as deep as one-and-a-half miles. The steam is sent through a maze of pipes to a nearby power plant run by the regional utility, to turn an electrical turbine.
There is virtually no sound to indicate all the steam whooshing around. And the power plant is simple enough that it can be controlled remotely from hundreds of miles away.
The Earth Policy Institute, a Washington group started by the environmentalist Lester Brown, argues that geothermal energy could provide as much as 80,000 megawatts of capacity in Japan — compared with only 535 megawatts now — and become a mainstay of its power production.
Advocates in Japan are more cautious. Sachio Ehara, an expert at Kyushu University, said the potential for geothermal energy was around 23,000 megawatts, although new technology could increase it. Geothermal could supply 10 to 20 percent of Japan’s electricity by 2050, he said.
The obstacles include operators of hot springs resorts, who worry that geothermal projects will sap their hot water. And many of the best hot water reservoirs are in national parks and therefore off limits to development.
Unlike solar or wind energy, geothermal power cannot be developed quickly because it takes years to explore and develop a field — analogous to prospecting for oil.
And largely because of drilling expenses, a geothermal power station costs about three times as much to build as a coal-fired plant of similar capacity, said Masaho Adachi, president of the Okuaizu Geothermal Company, which owns the geothermal facility here. But he said that high upfront cost is offset over time, because geothermal plants do not burn fuel.
Nonetheless, Okuaizu, a subsidiary of Mitsui Mining and Smelting, is losing money. But Mr. Adachi said the geothermal business would become more viable if the Parliament, as expected, enacted a law to require electric companies to buy geothermal energy at a premium.
Geothermal power, while considered clean energy, is not always perfectly renewable because a hot water field can be tapped more quickly than it can be renewed. The power plant here, which opened in 1995, is rated at 65 megawatts of capacity, but production has fallen to only half that level.
Geothermal, moreover, is not without risks. One worker at another facility was killed last October and another seriously injured when steam came roaring out of the ground where they were working. And there is a fear that the drilling, or the practice of injecting cool water back into the ground, could induce earthquakes. But at least Mr. Aoyama does not have to worry about a release of deadly radiation like that from the Fukushima Daiichi nuclear plant, 75 miles east of here. His main environmental concern is the rotten-egg smell of hydrogen sulfide, which can be harmful in high concentrations but not in the amounts likely to escape from the geothermal plant.
“It smells a little,” Mr. Aoyama said, “but not so much that the neighbors complain.”
