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Kyushu Electric goes ahead with 1st solar power production halt request

Kyushu Electric Power Co. grid operation division head Hiroshi Wani explains the company's request to suspend solar power generation at a press conference in Fukuoka, on Oct. 12, 2018. (Mainichi/Taiki Asakawa)

FUKUOKA -- Kyushu Electric Power Co. followed through with a request to halt solar power generation by other producers from 9 a.m. to 4 p.m. on Oct. 13 to avoid a blackout due to oversupply.

The request is the first of its kind to be executed in Japan, excluding the nation's remote islands, and halted 430,000 kilowatts-worth of solar power generation across six prefectures centered in the northern part of the island of Kyushu in southern Japan. The 430,000 kilowatts amounts to roughly 7 percent of the maximum projected production of electricity from solar and wind on Oct. 13.

With the restart of four Kyushu Electric nuclear reactors and the expansion of solar power generation, there has tended to be an oversupply of electricity during midday on the island. A severe power supply and demand imbalance could lead to widespread blackouts.

Suspension requests could be applied to the about 24,000 solar power and 60 wind power generators in Kyushu, not including those for family use, but Kyushu Electric did not include wind power in the Oct. 13 request. Most of the 9,759 solar generating stations to be covered by the measures are concentrated in Fukuoka, Saga, Nagasaki and Oita prefectures, with some in Kagoshima and Miyazaki prefectures.

According to Kyushu Electric, the weather on Oct. 13 is clear, and the solar power production between 12 p.m. and 1 p.m. was estimated to be a maximum of 5.94 million kilowatts. However, demand during that time period is only 8.28 million kilowatts, meaning that solar power alone would cover 72 percent of the amount. With the addition of nuclear and other power sources to the equation, it appeared there would be no way to avoid a massive supply-demand imbalance.

Electric power is difficult to store, and it is necessary to balance supply and demand. If this balance shifts too much, the worst-case scenario is a blackout. This is why Kyushu Electric made the decision to limit electric power generation at thermal plants such as Reihoku Thermal Electric Power Station in Reihoku, Kumamoto Prefecture, following government guidelines that prioritize curbing non-nuclear power generation first.

Kyushu Electric has tried to utilize its hydroelectric power plants and send electricity to other regions through a transmission line linking Kyushu to the main island of Honshu, but even then the company is left with an excess of 430,000 kilowatts. This led the company to make the decision to request the suspension of solar power generation.

"It is important not to have feelings of inequality develop between operators," Hiroshi Wani, head of the Kyushu Electric grid operation department, said at an Oct. 12 press conference held in Fukuoka, emphasizing that the company had selected a fair balance of producers per prefecture to which to serve the suspension request. "There is a possibility of (more requests) in autumn and spring," he added.

However, solar power producers have been left anxious. Tsutomu Sadatomi, head of the new energy project division of Chopro Co., a Nagayo, Nagasaki Prefecture-based company with 17 "mega solar" locations, said, "We don't know how the suspension request system will be implemented. If we don't ascertain the frequency of suspensions, it will be difficult to make financial arrangements to expand our solar power business."

In response to such worries, the Ministry of Economy, Industry and Trade plans to consider the conditions of the suspension at a government panel after it has been conducted, in the spirit of the importance placed on transparency and guaranteeing equality by minister Hiroshige Seko. The validity of the government's rule prioritizing nuclear power generation in the future will likely be called into question.

(Japanese original by Taiki Asakawa, Kyushu News Department, and Takayuki Hakamada, Business News Department)

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