What is the 'duck curve phenomenon' that stands in the way of large-scale development of solar power generation?
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Photovoltaic power generation using solar power, which is a renewable energy, has been attracting attention as a power generation method that does not give a burden to the environment, as the power generation cost has gradually decreased in recent studies. With such solar power generation, it is known that the problem of ' duck curve phenomenon ' will occur with large-scale deployment, and researchers are seeking to solve the duck curve phenomenon with that technique.
Solar power's greatest challenge was discovered 10 years ago. It looks like a duck. --Vox
https://www.vox.com/energy-and-environment/2018/3/20/17128478/solar-duck-curve-nrel-researcher
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In 2008, researchers at the National Institute of Renewable Energy (NREL) in the United States have a pattern in the curve representing electricity demand while making predictions about the large-scale deployment of solar power. I found that. The pattern is that 'the demand for electricity increases sharply from 6 am to 8 am when people start to wake up, and the demand for electricity increases again around 6 pm when people return home.' This curve seems to take almost the same shape, although there are some deviations depending on the season and region, but the deviation in power demand is not so large, and the conventional power supply system was sufficient to handle it.
However, NREL researchers predicted that 'the pattern of the electricity demand curve will change as the scale of solar power generation increases.' Photovoltaic power generation is a system that follows the natural operation of generating power as soon as the sun rises and ending power generation when the sun sets, unlike the system that can manage the amount of power generated at a conventional power plant. Therefore, the manager cannot control 'increase the amount of power generation' or 'suppress the amount of power generation', and supply power only during the time when power is being generated, and when power generation is completed, the power supply ends. Take a pattern. From the perspective of the operator of a conventional power supply system, we can find the rule that 'the power demand decreases by that amount while photovoltaic power generation is being performed, and the power demand increases by that amount when the photovoltaic power generation ends.' ..
If we look at the total amount of power demand minus the amount of power supplied by solar power generation as the 'real power demand', the power demand will decrease from morning to evening, and the power demand will increase sharply from evening to night. Will be. During the daytime when sunlight is available, solar power generation is carried out, and the real power demand decreases by that amount, but during the nighttime when sunlight is not available, all the power demand is covered by conventional fossil fuels and nuclear power generation. The need to cover it will increase the real demand for electricity. The curve that represents the real power demand draws a larger curve as the scale of photovoltaic power generation increases and the amount of power generation increases.
Since the curve that represents the real power demand considering solar power generation looks like a duck, the phenomenon that the real power demand fluctuates greatly due to solar power generation is called the 'duck curve phenomenon'.
Many power supply system operators are not accustomed to the task of responding to the duck curve phenomenon by sharply reducing power generation in the morning and increasing power generation in the evening. In addition, since the sudden start and stop of power plants requires extremely high costs, there was concern that the duck curve phenomenon would put a brake on the movement to promote solar power generation.
Since its discovery in 2008, many people have been focusing their wisdom on solving the duck curve phenomenon, and now several solutions are being shown. Paul Denholm, who heads the NREL research team, talks about the solution to the duck curve phenomenon and the outlook for solar power generation in an interview with the American news web media
Denholm cites 'sharing sunlight over a wide area' as one of the ways to solve the duck curve phenomenon. In areas such as the United States where the land is long in the east and west, there is a large difference between the time when the sun rises and the time when the sun sets, even within the same country, and in fact, four time zones are set in the United States. If the electricity produced by solar power generation in the area where the sun rises in the morning is sent to the area where the sun has not yet risen for use, it will generate power slowly while suppressing the gap in real power demand. You can change the amount of power generated at the place. Or vice versa, it is possible to close the gap in real electricity demand by sending electricity produced in areas where the sun is still rising to areas where the sun has set.
by gracelinks
A feed-in tariff system that enables smooth trading of electricity generated by solar power generation may play a major role in the solution of 'sharing electricity in a large land with different sunshine times.' However, in order to operate this method efficiently, a system to monitor the amount of power generation and real power demand of the entire country is required, and a major reform of the power supply system is required.
On the other hand, there is also the idea of bridging the gap in power generation by combining solar power generation with other methods that utilize natural energy such as wind power generation and geothermal power generation. However, according to Mr. Denholm's outlook, renewable energy such as wind power generation is affected by the seasons and time zones as well as solar power generation, and it is difficult to establish a completely complementary relationship.
One of the methods that Mr. Denholm may be able to do is to 'store the electricity obtained from solar power generation during the day with a storage battery and release the electricity at night.' Batteries that store large amounts of electricity are now expensive, but Denholm believes that the price of batteries will eventually fall and that solar-generated electricity will be easier to use even at night.
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However, Mr. Denholm says that what he needs most is that each of us has an awareness of 'reducing electricity consumption at night.' If it is difficult to change people's consciousness with words alone, it is necessary to work to curb electricity consumption from evening to night by changing the electricity charge depending on the time zone.
According to Mr. Denholm's outlook, the ratio of renewable energy including solar power generation does not seem to account for 100% of the total power generation, and at most 80%. 'Why do people think that the ratio of renewable energy should be increased to 100%? 80% is covered by renewable energy, and the remaining 20% is covered by conventional fossil fuels and nuclear power generation. I think that's enough, 'said Denholm, who expects that 100% renewable energy would be costly.
Of course, at present, the ratio of renewable energy has not reached 50%, let alone 80%. With various issues remaining in the operation of photovoltaic power generation, such as the development of a nationwide power grid and the improvement of storage batteries, Mr. Denholm said that he will continue to work toward solving the problems of photovoltaic power generation.
by James Moran
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