FUKUOKA -- Kyushu Electric Power Co. suspended operation of thousands of solar power generators run by independent operators in the Kyushu region on Saturday and Sunday.
The measure, taken to forestall power shortages that could have resulted from an imbalance between supply and demand, was the first such move ever taken in the nation, with the exception of remote islands. The case brought to the fore inevitable problems -- mainly related to the weather -- with renewable energy, which the government plans to utilize as a major power source in the future.
An official on duty at Kyushu Electric's load dispatching center temporarily shut down 9,759 solar power generators at 11:30 a.m. Saturday via remote control, reducing power output by 430,000 kilowatts.
"Of course we'd be happier if such measures never took place, but if it's necessary to accommodate the advance of renewable energy, we must accept it," said a representative of an independent operator based in Tokyo. While the operators lose revenue in such cases, power companies are not obligated to compensate them under the law.
When imbalances in the supply and demand of electricity arise, the frequency of electricity will be disrupted, which increases the possibility of power failures. The September blackout that affected most of Hokkaido was caused by overwhelming demand after a power plant malfunctioned following an earthquake.
The suspension in Kyushu was necessitated by opposite circumstances, as the power company took steps ahead of a predicted excess in supply.
The generation of large quantities of power due to sunny weather on Saturday, when industrial consumers and businesses have the day off, was one reason for the move. The company also forecast less use of air conditioning due to a drop in the temperature.
Kyushu Electric decided to manipulate its power output based on rules set by the government. The company predicted total demand that day of 8.28 million kilowatts versus supply of 12.93 million kilowatts.
The excess supply turned out to be 430,000 kilowatts after 2.26 million kilowatts were used to pump water for hydropower and store power in storage batteries. Another 1.96 million kilowatts were transferred to another power company.
.As fine weather continued the following day, Kyushu Electric forwent generation of up to 540,000 kilowatts worth of electricity on Sunday. The company said ordinary households that produce fewer than 10 kilowatts were not subject to the suspension.
Such moves could hinder the development of renewable energy if administered too often.
The spread of solar power was accelerated with the introduction of the feed-in tariff system in July 2012. Operators flocked to the Kyushu region, which enjoys abundant sunlight and where land prices are relatively low. While the region only accounts for about 10 percent of land in Japan, it contains about 20 percent of the country's solar power generation facilities.
Under the new Strategic Energy Plan adopted by the Cabinet this summer, the government will seek to raise renewable energy's share of total power output to between 22 to 24 percent by 2030, making it a major source of power.
However, renewable energy, including wind-generated power, is easily affected by weather. As a result, the supply is unstable compared to thermal and nuclear power.
The case of Kyushu Electric also revealed the complexity in controlling supply and demand.
Power companies can better utilize excess electricity through several methods, including improving the transmission networks through which electricity is sent to other companies. Kyushu Electric already employs such an approach, sending excess power to its counterparts in Honshu. Unfortunately, the amount of power delivered is limited by the capacity of transmission lines. Upgrading the lines would require substantial investment.
Storing electricity is another option. However, this approach "would require time to put into practice" due to the physical capacity and cost of storage batteries, according to a senior official at the Economy, Trade and Industry Ministry.
Alterations to the power supply must also be done in a manner fair to the independent operators. A senior official of Kyushu Electric noted the importance of ensuring "the number of suspensions affecting each operator is the same by the end of the fiscal year."
However, the company has not released the names of those affected by the most recent suspension.
The 44-year-old president of an operator based in Fukuoka said he received an email from Kyushu Electric instructing him to suspend operation of seven of his generators on Sunday. "I hope they're fairly choosing who's affected," he said, expressing skepticism of the process.
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