Output Control Rate of 5% or Less, Real-time Control Are Essential, Expert Says
The first output control on the mainland was executed in Kyushu Oct 13, 2018. The frequency of the control was seven days in total over two months from October to November of that year. The frequency increased sharply this year to 16 days in March and 19 days in April. Because the power cannot be sold during the period when the power output is highest, power producers are concerned about a decline in the business feasibility and are beginning to refrain from new developments in the Kyushu area.
We interviewed Project Professor Yo Yasuda of the Graduate School of Economics at Kyoto University, who is familiar with output control in overseas countries.
'More renewable energies can be introduced by output control'
Q: Output control in the areas covered by Kyushu Electric Power Co Inc (Kyuden) has been increasing sharply since this spring, and the power generated by renewable energies is wasted without being used, which is sometimes criticized.
Yasuda: I would like to point out first that the need for the "output control," an operation method of renewable energies and the issues on output control in Japan should be discussed separately.
In Japan, criticisms are often heard about the output control executed by Kyuden for the first time on the mainland. However, the output in low-load periods in the daytime is generally controlled throughout the world for grid operation in the process of introducing large-scale solar power and wind power. The solar power and wind power introduction amount can be increased by temporarily controlling the output, which is a common perception.
Q: Power companies including Kyuden recently began to emphasize the theory of "increasing the amount of renewable energy introduction by output control", but power producers often say, "The stopping of output in spring, when the power generation amount is the highest among the four seasons, is a serious problem for us."
Yasuda: I understand their opinion, but construction of second and third power stations for example, following the first one, will be possible if they accept a certain level of output control, based on the assumption that many more solar power plants need to be constructed in Japan. Power producers who say "output control is absolutely unacceptable" are talking on behalf of vested interests of existing solar power plants.
If the business feasibility was severely damaged by the level of the output control by Kyuden in fiscal 2018, there was a problem in the initial business plan of the power plant.
Solar power producers in Japan agree to the "30-day rule," which is a rule to accept output control up to 30 days with no compensation, for grid connection. The amount corresponds to approximately 8% in the output control rate (power loss ratio). The output control rate in fiscal 2018 is estimated to be less than 1% (Kyuden disclosed that the rate was 0.9% after the interview), and there is a lot of room to increase the rate.
The media targeting the general public tend to report verbatim the pessimistic views of power producers regarding the output control by Kyuden and they are making a big deal about the impact of output control.
Ratio 2 to 3% in Spain
Q: However, output control was executed 17 times in March and 19 times in April this year, and the frequency increased sharply. If the frequency continues to increase at this speed, it is possible that the frequency reaches the upper limit of the "30-day rule," which is 30 days per site.
Yasuda: The number of days on which output control was executed increased sharply in March and April, but the output control rate cannot be estimated based on the number of days alone, and therefore, I cannot evaluate the situation at this stage. The output is controlled only during the period around noon, when balancing the supply and demand is the most difficult, in some cases, because Kyuden can control large-scale solar power plants by remote operation. It is possible that the controlled amount is not so large as the amount you imagine from the number of days.
In any case, we hope that the output control rate data is disclosed as soon as possible. The data is normally disclosed one month after output control in Japan, but the control amount is sometimes disclosed on the next day in some overseas countries.
Q: An expert meeting of the Ministry of Economy, Trade and Industry (METI) (New Energy Subcommittee, Grid Working Group) indicated that the output control rate will be 10 to 20% for the "rule for designated power producers" that connect their power plants to grids under the limitless and no compensation output control conditions based on the estimated value for calculating the connectable amount (30-day equal output control framework) in some cases when solar power introduction is accelerated.
Yasuda: It was indicated that the output control rate in Japan is 8% at maximum for power producers covered by the "30-day rule" while it is likely that the rate could be double figures for power producers covered by the rule for designated power producers. From the global viewpoint, it is unlikely that the output control rate rises to this level following introduction of large-scale renewable energies.
For example, in Ireland, which is similar to Hokkaido in area, population, demand for power and grid scale, the ratio of renewable energies mainly consisting of wind power reached 30%. The introduction amount is about 20 times that of Hokkaido, but the output control rate is only slightly more than 5%.
The output control rate of "5%" is comparatively high in Europe, and the rate is as low as 2 to 3% in Spain (Fig. 1). The consensus in Europe, where wind power and solar power were introduced earlier than other countries, is to keep the output control rate to around 5% by accumulating knowhow on grid operation. The EU directive specifies minimization of the output control amount.
ICT function essential for 10 years
Q: The policy of keeping the output control rate to several percent while introducing large-scale renewable energies is completely different from the stance of Japan, which is "to increase the rate to a certain level when the amount of renewable energies increases to a certain level."
Yasuda: The concept is different between Europe and Japan. In Japan, the logic of "setting a limit to the introduction of renewable energies based on conventional grids and operation" is in the mainstream, while new grid operation technologies and methods are searched for in Europe to find out measures "to improve the grids and operation methods, aiming to keep the output control rate below 5% on the premise of large-scale introduction of renewable energies."
The gap between the concept of Japan and that of Europe is that Japan is in the 20th century while Europe is in the 21st century. It is apparent which will lead the world in the future in power systems and grid technologies.
Q: What kind of technical innovation made it possible to keep the output control rate at about 5% in Europe, where renewable energies have been introduced on a larger scale than in Japan?
Yasuda: No special measures are taken, but the ICT (information communication technology) is always introduced to renewable energy equipment for real-time control. It is common practice throughout the world. In Spain, for example, mounting of the ICT function was made compulsory for connection of wind power facilities to grids in 2006, more than ten years ago.
Real-time control of wind power and solar power by ICT is not a very sophisticated method in terms of technologies and is made possible by systems and laws.
The large-scale introduction of solar power was started in Japan without establishing a system of this kind, which was a big mistake. The developers finally noticed the mistake and began to mount remote control systems. Trial and error are always required in establishing systems, and it is natural that pioneers of renewable energies such as Denmark and Spain go through a trial-and-error process. Japan, which was behind other countries in introducing renewable energies, did not try to learn from the pioneers.
However, the introduction of real-time control will be accelerated in Japan in the future. Then, the output control rate will be 5% at maximum and will drop to 2 to 3% if normal efforts are made for grid operation. Problems will occur if the rate exceeds the range, but such situations will be caused only when the efforts are insufficient.
Purchase prices pushed up because of '30-day rule'
Q: METI finally began to discuss the legal requirements for grid connection of renewable energies, naming the requirements the "grid code." What do you think is the cause of the delay?
Yasuda: The number of renewable energy specialists who are familiar with power systems and the number of power system specialists who are familiar with renewable energies are extremely small in Japan. Because of this, human resources for bridging between renewable energies and power systems are insufficient. Human resources for bridging between them are abundant in overseas countries. Precisely speaking, these specialists exist in major power companies in Japan, but the number is limited and I believe their opinions did not reach management.
Under such circumstances, persons responsible for the policy were not aware of the importance of real-time control when the feed-in tariff (FIT) scheme was introduced and installation started.
Q: The "30-day rule" and "output control of 8%" systems are far from the global standard.
Yasuda: It is important for renewable energy producers to know the maximum output control rate in advance to plan financing. They can work out business plans according to the rate, which is set at 5%, 8% and so forth. An extremely high rate of "8%" was set as the assumed rate in Japan and the rate was reflected in the finance costs, resulting in the high purchase prices. In that sense, the rate negatively affects the national economy, leading to the general public losing money.
In the first place, the control rate per "kWh" should be set as the target value, instead of the control rate per days or hours. If the rate is set assuming frequent real-time control, the above idea will be incorporated naturally.
Q: When we look back on the flow of the Grid Working Group, we felt that the WG intended to cool down the development of renewable energy facilities by making it difficult for developers to obtain financing by introducing the rule for designated power producers and increasing the output control rate.
Yasuda: The image of "output control equals evil" is partially attributable to the initial messages from the government and power producers, which raised concerns about the future. The image of output control was damaged because of their own messages. If advantages were fully explained by saying "output control of this level is required for large-scale introduction of renewable energies of this level" from the start, power producers would have accepted it more positively and cooperated with the government.
Q: The target value of 64GW (7% of all power sources) set for solar power in the Energy Mix is about to be achieved now, but the government cannot announce its vision on the further increase of renewable energies and solar power in the future, which is building a sense of distrust in the renewable energy policy. This situation tends to discourage the development of new facilities and strengthen the efforts to maximize the profit from existing power plants.
Yasuda: "Solutions" to the issues of nuclear power plants have yet to be found, and that brings about the situation where Japan cannot present a long-term vision of renewable energies. Because of this situation, the government cannot announce the target value for introduction of renewable energies in 2050 although it made an announcement on the policy to use renewable energies as "main power sources."
If it is impossible to find out "solutions" to the issues of the nuclear power plants for the time being, I believe the government can set a long-term goal for renewable energy introduction apart from the issues.
A renewable energy research institute in China announced a long-term goal to achieve "a renewable energy ratio of 90% in power sources in 2050." The remaining power will be supplied by nuclear power plants and coal-fired power plants at a ratio of 5%, respectively. The announcement was not made by the government, but the intentions of the government and the communist party seem to have been reflected in the announcement because it is a national research institute.
Countries throughout the world are making genuine efforts to restructure their power systems with renewable energies at the core. If target values are not announced for renewable energies beyond "22 to 24%" set for 2030, Japan will be stuck in the 20th century and be left behind other countries in power system technologies.