What is needed to make renewable energy a common resource

Renewable energy spread through the FIT scheme

Promoting the use of renewable energy as a clean energy source is extremely important not only for the world but also for Japanese society. However, there are a variety of issues to be overcome to achieve the above.

The first thing, of course, is to increase renewable energy generation facilities. The feed-in tariff scheme (FIT scheme) was established in 2012 as a measure for that purpose.

As many of you may know, this is a scheme in which conventional electric power companies purchase all electricity generated using renewable energy at a fixed price during a fixed period of 10 or 20 years under certain conditions.

With the start of this scheme, businesses engaged in solar power generation and the like have been established nationwide, and the number of people who install solar power generation facilities on the roofs of ordinary houses has increased considerably. As a result, the ratio of power generation using renewable energy sources has increased, reaching approximately 15% of all power generation in fiscal 2019.

However, there is a problem. The cost of electric utilities’ purchasing electricity is to be borne by consumers according to the amount of electricity they use under a surcharge system. In 2019, the cost reached the enormous amount of 2.4 trillion yen.

To reduce the burden, the FIP (Feed-in Premium) scheme, in which electricity is purchased at the market price with the addition of a subsidy (premium), will be introduced in fiscal 2022.

In the first place, it is not well known that electricity is traded in the market, but with the deregulation of electric power, the Japan Electric Power Exchange (JEPX) was established in 2003. Power generators and electricity retailers bid to buy and sell electricity at this place.

For example, the price of electricity increases in the daytime in summer when the demand for electricity is high, and the price decreases in spring and autumn or at night when the demand for electricity is low. Of course, demand is not the only factor that determines market prices, but the balance between supply and demand is a major factor in determining electricity prices.

Basically, if the supply of renewable energy increases as the number of power generation facilities increases, the market price will go down, and so will the electricity rate.

Under the FIP scheme, if the market price is sufficiently lower than the fixed purchase price under the FIT scheme, you will only bear the amount of the subsidy (premium) as a surcharge instead of the difference between the FIT price and the market price as a surcharge. As a result, the burden of your surcharge will be reduced.

Also, sellers of electricity want to sell electricity when its price is higher, but that is when the electricity demand is high. If the amount of electricity sold increases at that time, it will lead to balancing supply and demand.

This is very important for the stabilization of the electric power system, and I think the FIP system is intended to fulfill this function.

Electricity supply and demand always need to be balanced

The big difference between electricity and general products is that electricity cannot be produced in advance. In other words, the electricity we are using now is the electricity being produced at some power plant now.

This is because it is difficult to store a large amount of electricity. Another reason is that if the amount of electricity generated and the amount of electricity used are not consistently the same, the power system will become unstable.

The image of supply and demand is that if the amount of supply of a product falls short of the amount of demand, some people will not be able to use that product. But in the case of electricity, it is a little more complicated.

To put it simply, if the balance between supply and demand of electricity is lost, the frequency of electricity will be disturbed. Frequently is a cycle in which the positive and the negative AC are interchanged, and you know that the frequency is 50 Hz in eastern Japan and 60 Hz in western Japan.

The electric power system in Japan mainly employs AC power transmission, which makes it easy to transform a current, and the electricity delivered to each household is also AC. If this frequency is disturbed, the normal supply of electricity becomes impossible.

If that happens, a safety device will be activated to stop the power plant. That means an imbalance between demand and supply may cause a power outage.

In fact, during the 2018 Hokkaido Eastern Iburi Earthquake, power plants located close to the epicenter, including the Tomato-Atsuma Thermal Power Plant, the largest power plant in Hokkaido, were shut down one after another, greatly disrupting the balance between power supply and demand.

Its impact spread to various power plants in Hokkaido and their operations stopped in succession, resulting in a blackout throughout the vast area of Hokkaido.

To prevent such a situation from happening, electric power companies and other organizations are working to increase the supply amount and enhance the safety of their facilities.

However, it does not mean that simply generating a large amount of electricity is enough. If too much power is generated, the frequency will be disrupted and the power plants shut down. The bottom line is that in order to maintain a stable power system, supply and demand must always be in balance.

Therefore, more accurate power demand forecasting becomes an essential and very important task.

In fact, it is known that the demand for electricity in society tends to be linked to weather conditions such as temperature and humidity, as well as days of the week and holidays.

For example, on a hot summer day, the use of cooling equipment such as air conditioners increases, and the power consumption increases consequently. Electricity consumption also increases on cold winter days as heating equipment is used. On the other hand, less electricity is consumed in spring and fall when the climate is mild.

In addition, there is a difference in power consumption between weekdays, when offices or factories are in operation, and weekends, when they are not in operation. Mondays and the days after holidays also show different trends among weekdays.

Based on the actual data of these past trends, electric utilities take in weather forecasts and other data, and use AI, which has gone through a series of learning through neural networks, to calculate power demand forecasts for the long term, the next day, and the next hour, and make power output plans. At present, it is said that the error of prediction is several percent.

Research to further improve the accuracy of these predictions is being conducted at various research institutions, including electric power companies and our laboratory.

After all, since power consumption changes depending on the will and the behavior of people who perceive physical phenomena such as the weather, if we can capture and quantify the movement of such people, we may be able to further improve the accuracy of predictions.

For example, we can interpret postings on SNS as people’s intentions and actions and quantify them in real time. It is a difficult challenge, but I think it is worth studying.

Increasing renewable energy while maintaining a stable power system

As mentioned at the beginning, increasing the use of renewable energy, which is a clean energy source, is essential for building a sustainable society.

However, in order to do so, there is an issue of not only increasing the amount of power generated from renewable energy sources, but also how to maintain a stable power system.

For example, the amount of power generated by photovoltaic and wind power depends on weather conditions. It does not necessarily correspond to the electricity demand of society. How to consistently match supply and demand is a major challenge.

One of the measures to help solve this issue is the development of storage batteries. Storing the generated electricity and transmitting it according to demand will lead to stability of the power system.

In fact, unlike thermal, hydro, and nuclear power, which are generated by turbines, solar power generated by solar cells is highly variable in output, thus storage batteries have already been used to smooth it out.

In recent years, the development of large-capacity storage batteries has been progressing. However, as they are quite expensive, it is difficult to put them into practical use. For this reason, reducing the cost of large-capacity storage batteries has become an important development theme.

Pump-up power generation, which functions as a storage battery, has been introduced to utilize surplus electricity at night.

As a matter of fact, it is efficient to operate nuclear power plants, of which the unit cost of power generation is low, with a constant output. However, if that is done, a surplus of electricity may be produced at night when the electricity demand is low.

To address this issue, reservoirs are built in a place with a height difference, and a pump is operated with surplus electricity to pump up the water from the lower reservoir to the upper reservoir. When the electricity demand is high, the water in the upper reservoir is discharged to generate hydroelectric power. This means that you can control the amount of electricity as needed.

Such a mechanism has begun to be used for renewable energy as well.

Efforts are being made to increase the electricity generated from renewable energy sources while maintaining the stability of the electric power system through such mechanisms and technological development as well as improving the accuracy of power demand forecasts.

Today, electricity is something we take for granted, like air. It is thanks to the efforts of our predecessors and technological progress.

Our goal is to continue to supply electricity as a naturally usable energy and to build a clean and sustainable society.

* The information contained herein is current as of June 2021.
* The contents of articles on Meiji.net are based on the personal ideas and opinions of the author and do not indicate the official opinion of Meiji University.
* I work to achieve SDGs related to the educational and research themes that I am currently engaged in.

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