Securing a stable supply of electricity and steadily increasing renewable energy: It is essential to strike a balance between these two goals.
Kyushu Electric Power Co. has implemented an "output control" measure, in which some solar power generators are temporarily suspended on sunny Saturdays and Sundays.
The measure has been taken because the balance of power supply and demand becomes disrupted when lower demand than on weekdays leads to an excess in supply generated from sunlight. Excessive supply causes electrical frequency disruptions that could cause a major blackout if the imbalance is left unattended. (The same phenomenon will also occur in the case of an electricity shortage.)
While it is desirable that renewable energy sources, such as solar power, be utilized as much as possible, undermining a stable supply system will do more harm than good. This measure can be regarded as inevitable to protect their electricity networks.
In the Kyushu region, progress has been made on the introduction of solar power generation by taking advantage of the region's abundant sunlight. At peak output on a sunny day, solar power generators in the region have a supply capacity of about 8 million kilowatts, equivalent to the output of eight nuclear power reactors.
However, the supply capacity of solar power significantly declines after sunset and when weather conditions worsen. To make up for this, nuclear power and other baseload power sources, which have stable output, must be in operation.
Kyushu Electric had tried to maintain the supply-demand balance by suspending some thermal power operations and transferring excess electricity to other companies. However, the company found it difficult to cope with the situation through these measures only.
Balance energy mix
In such cases, electric power companies are allowed to ask solar and wind power business operators to temporarily halt their power generation in line with rules set by the government. We can say this system is reasonable.
The temporary suspension targets 5 percent to 9 percent of the total solar power generation per day. Kyushu Electric is urged to make the utmost efforts to adjust the balance of supply and demand and avoid taking the output control steps as much as possible. The company should appropriately disclose information about the prospects of its future output control measures.
It is not only Kyushu Electric's service area that is facing difficulty in adjusting supply and demand due to an increase in solar power generation. About 40 percent of solar power generators certified by the government from fiscal 2012 to 2014 have yet to become operational. If these generators start working, the difficulty in making adjustments will become greater.
Every power company must seriously consider measures to accommodate solar and other energy sources without difficulty.
One possible measure will be adjusting electricity excesses and deficiencies over a wider range of areas by further strengthening interconnection lines between power companies.
It is desirable to promote the "diversification of energy sources," which will enable each region to supply electricity for itself in the future, by developing low-cost, large-volume storage batteries. But technical hurdles remain high.
It is also necessary to rectify the distorted composition of renewable energy sources, which places disproportionate weight on solar power. The government intends to make renewable energy one of the nation's main power sources. But if the energy mix is not diversified by increasing the shares of offshore wind power and biomass power generation, it cannot achieve such a vision.
(From The Yomiuri Shimbun, Oct. 20, 2018)
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