On March 21, 2022, the Agency for Natural Resources and Energy issued an "Electricity Supply-Demand Stress Alert" for the area served by Tokyo Electric Power Company (Tokyo, Kanagawa, Saitama, Chiba, Tochigi, Gunma, Ibaraki, Yamanashi, and Shizuoka prefectures east of the Fuji ^River1). The alert is intended to alert the public that there may not be enough electricity available from power companies (supply) to meet the electricity needs (demand) of homes, stores, and businesses, and to encourage people to conserve electricity (save power). In response to this, Tokyo Sky Tree and Tokyo Tower cancelled their lighting on the 22nd, and many people may have said, "I saw it on the news. In the service area of Tokyo Electric Power Company (TEPCO), an electricity supply-demand crunch alert was also issued for four days in late June 2022, and many households, stores, and businesses cooperated to save electricity. In this issue, we will consider why there is a shortage of electricity and what can be done to effectively save power.

If we don't have enough power, why don't we just increase the amount of electricity we generate?" --Some of you may be thinking, "If there is not enough electricity, why don't we just increase the amount of electricity generated? It is true that if power plants could produce more electricity and deliver it to the places where it is used, the problem would be solved. In reality, however, it is not that ^simple2).

One of the reasons for this is that there are power plants that are not operating: many nuclear power plants have been shut down as of 2022 due to the Great East Japan Earthquake that occurred on March 11, 2011. Various measures must be taken to get these back in operation.

The same is true for thermal power generation, where the number of operating power plants is decreasing. Thermal power plants are being shut down and decommissioned one after another, partly because their equipment is getting old and partly because of the global trend toward decarbonization. Furthermore, there are hurdles to increasing the amount of electricity generated by thermal power plants, such as the rising price of liquefied natural gas (LNG), which is used as fuel, and the fact that selling the electricity generated by thermal power plants is not profitable.

Renewable energies such as solar and wind power are expected to make up for the decrease in nuclear and thermal power generation. In fact, the amount of electricity generated from renewable energy sources is increasing, but natural conditions such as sunshine hours and wind speed are constantly changing, and the amount of electricity that can be generated is not always the same.

The inability to store large amounts of electricity, which is unique to electricity, is another reason why the amount of electricity generated cannot be increased. At a power plant, electricity is generated by rotating generators, but if a large amount of current is suddenly required to flow, it becomes difficult to keep the generators rotating at a constant speed. Therefore, the amount of electricity generated must be as close as possible to the amount ^used3)4).

For this reason, we are required to "save electricity" by reviewing our electricity usage to see if there is any waste.

So, when you actually decide to save electricity, what actions should you take?　There are three main approaches to power conservation: (1) peak shaving, (2) peak shifting, and (3) bottom-up. Peak cut (1) refers to reducing the amount of electricity used during the "peak hours," which are the hours when the most electricity is used in a day (around 1:00 p.m. to 4:00 p.m. in the summer). Peak shift" refers to shifting the time of day when electricity is used from peak hours to off-peak hours. Bottom-up" means to use electricity late at night when less electricity is consumed.

Did any of the three ideas for saving electricity make you think, "I can do this"? Peak shaving may be someone who says, "I am still doing it. On the contrary, you may have felt that peak shifting "seems difficult. The reason it seems difficult is because it requires storage batteries.

Storage batteries can also be used in the event of power outages due to disasters, making them useful as emergency supplies. However, storage batteries for home use are still expensive, and only a limited number of homes have them, so many people will not have a clear idea of what they are talking about when they say, "Let's use storage batteries for peak shifting.

However, there are actually things around us that work in the same way as storage batteries for home use. Here are some examples.

There are three ways to think about saving electricity: peak shaving, peak shifting, and bottom-up, and there are many appliances around us that can put these ideas into practice. Please try to imagine which of the three ways of thinking about saving electricity you know applies to you and which you can easily implement. In doing so, you may find ways to save electricity that you were not aware of before.

For example, peak-shift functions may be found not only in mobile devices, but also in refrigerators, televisions, and fans. Once you know this, you may want to try using various peak shifting functions. It would be interesting to hear from people in homes that have automated peak shifting through the use of HEMS (Home Energy Management Systems) and HEMS-controlled air conditioners, ventilation fans, televisions, etc., why they started using HEMS and how effective it has been. ¹⁰⁾.

When people hear the word "energy conservation," they often think, "I'll just put up with the heat," or "I'll just put up with the dark. However, if we are skillful, it is possible to save energy while maintaining comfort. It is important to understand the mechanism of power saving and practice it without any difficulty.