30 Août 2015
August 30, 2015
By JUNICHIRO NAGASAKI/ Staff Writer
KOKONOE, Oita Prefecture--Because it is volcanically active, the island of Kyushu is ideally suited to geothermal power generation. That prompted Kyushu Electric Power Co. to announce an ambitious plan on Aug. 5 to double its geothermal output by 2030.
Even though geothermal power accounts for a miniscule share of overall electricity demand, the regional utility said it plans to gradually add more power stations in years to come. One bonus is that geothermal generation offers a more stable electricity supply source compared with solar or wind power.
Kyushu Electric held a completion ceremony on Aug. 5 at the Sugawara Binary Cycle Power Station, a geothermal power generation facility in the town of Kokonoe in Oita Prefecture. With an output of 5,000 kilowatts, it will produce approximately 30 million kilowatt hours a year, or enough to power 8,000 typical homes.
The station's operator is Kyuden Mirai Energy Co., a subsidiary that works with renewable energy.
Including this facility, Kyushu Electric operates seven geothermal power stations in Kyushu. One of them is the Hacchoubaru Geothermal Power Station, an 110,000-kilowatt facility in Kokonoe that is the largest of its kind in Japan. The power company's total geothermal output is around 200,000 kilowatts, accounting for 40 percent of all geothermal generation in Japan.
At the ceremony, President Michiaki Uriu revealed that by 2030, Kyushu Electric will roughly double its current output by adding 180,000 kilowatts. The company has plans for new facilities in Minami-Aso in Kumamoto Prefecture and Ibusuki in Kagoshima Prefecture, but Uriu stated, "That will not be enough. We will add yet more."
Like other utilities, Kyushu Electric is obliged to diversify its power sources in the aftermath of the 2011 nuclear disaster in Fukushima Prefecture.
Solar power generation has rapidly expanded in Kyushu. However, Kyushu Electric has placed restrictions on purchases of solar power because the amount of electricity produced is precariously affected by the weather.
Geothermal power offers a stable supply.
"It doesn't suffer from the disadvantage of fluctuating with weather conditions. So if we can properly manage the resource, we can generate electricity for perpetuity," Uriu said.
While there are expectations that geothermal power will act as a "baseload" power supply around the clock, the technology has been slow to spread. Even at Kyushu Electric, which has the edge over other regional utilities in the development of this technology, geothermal generation only accounted for around one percent of the power supply capacity this summer.
One reason is resistance from local hot spring inns and others who worry that the source of the hot springs will be depleted. The recently completed Sugawara Binary Cycle Power Station uses a well, locally-owned by the town of Kokonoe, to capture steam. In return, Kyushu Electric pays the town about 100 million yen ($830,000) a year as a steam purchase charge.
This mechanism provides a large benefit for the local community.
"We have to have a mutually beneficial relationship with local communities," Uriu said. "We will use this as a model case and continue to develop geothermal power generation into the future."
Geothermal power is typically generated by taking extremely hot and pressurized steam that rises from the ground to spin a turbine, whereas "binary power generation" can produce electricity even if the steam's temperature is relatively low.
With this approach, pentane and other substances with a low boiling point are heated with the steam and evaporated, and the subsequent steam spins the turbine. Although the output is relatively small, it means that more sites can be used as power stations. And it is this factor that is expected to help spread the technology.