Power network supporting a stable electricity supply

Now, in our daily life, we take it for granted that lights and household appliances operate normally just by the flick of a switch. In today’s society, where electric wires stretch far and power outages are rare, it has been taken for granted that electricity is available.

However, in recent years, there have been many incidents in which the supply of electricity has been revealed to be unexpectedly weak.

For example, in 2018, there was a blackout that knocked out power throughout Hokkaido. It was triggered by the Eastern Iburi Earthquake which recorded a maximum seismic intensity of 7. The Tomato-Atsuma thermal power plant, the largest power plant in Hokkaido, was shut down by the earthquake.

However, Hokkaido is as large as the Kanto and Chubu regions combined. There are other thermal power plants, hydroelectric power plants, wind power plants, and so on. So, why was the electricity supply cut off all over Hokkaido? It has to do with the nature of electricity and the power network.

Electricity continues to be consumed as it is generated from power plants. In other words, the plants are controlled to generate only the amount of electricity needed.

One of the reasons is that electricity cannot be stored. In other words, there is no way to control its amount such as by inventory adjustment.

You may not think that is true. We have cells and batteries around us, and we use them conveniently for smartphones and laptops. However, the scale of electricity generated by power plants is different. You cannot store the electricity in cells.

Of course, the development of large storage batteries for power generation facilities is also progressing, making the storage technically possible. However, it is very expensive. It is still difficult to install a large number of large storage batteries.

That is why electric power companies are constantly generating electricity to ensure a well-balanced supply while looking at the demand for electricity.

In addition, if the balance between supply and demand is disrupted or there is a large fluctuation, frequency and voltage will fluctuate.

Frequency is the number of times that the flow direction of alternating current (AC) electricity changes as its size and direction periodically change over time. The number of cycles per second is expressed in Hz. In Japan, it is 50 Hz in eastern Japan and 60 Hz in western Japan.

The household appliances that we use every day are made to operate with this frequency standard. Therefore, electric power companies send AC electricity that matches the respective frequency.

Also, Japanese home appliances work at a voltage of about 100 V. That means the power companies supply electricity while maintaining a voltage of about 100 V.

This frequency and voltage can be maintained because the plant’s generators and substations are operating steadily.

For example, when controlling the amount of electricity generated in order to balance supply and demand, it is not controlled by a single power plant, but by all the power plants connected in parallel.

In other words, even if you change the amount of power generated, all of the generators in the power plants that are networked operate synchronously; at the same revolution speed to adjust the generated amount. The frequency is kept in that way.

Conversely, even if there is a sudden change in electricity consumption, the fact that each power plant is networked prevents any particular power plant from causing large fluctuations.

If only one power plant responds to fluctuations in electricity consumption, the number of revolutions of its generators would change significantly.

Moreover, the fluctuation would be propagated to other power plants in the network. Then, the electricity from all those power plants would become unstable.

In this case, the power generation facility may be damaged. Usually the safety equipment of the facility works, and the generator automatically shuts down.

Microgrids attracting attention as a next-generation power network

In Japan, the power companies managed the amount of electricity well, took advantage of the benefits of these power networks, and vulnerabilities were rarely exposed. However, the blackout in Hokkaido exposed those vulnerabilities.

The earthquake caused the first shutdown of Units 2 and 4 at the Tomato-Atsuma thermal power station. This caused an excessive load on Unit 1, resulting in an imbalance between supply and demand and a drop in frequency. It is believed that this spread to various power plants in Hokkaido, eventually shutting all power plants in the vast area across Hokkaido.

In addition, a long-term power outage occurred in Chiba in 2019. The origin of this was electric poles and steel towers brought down by a direct hit from a typhoon.

To start with, rebuilding the poles and steel towers and redrawing new electric wires is hard work and takes time. In addition, since the electric power network is spread out throughout the region, it is not easy to transmit power sequentially from the area where the electric wires are being redrawn.

That is why power outages continued for a long time in large areas.

As a result of this series of accidents that exposed the vulnerability of power networks, discussions on next-generation power networks have intensified. One of the hot topics is the microgrid.

The idea behind the microgrid is not to rely on a wide electric power network, but to consume locally produced electricity.

This concept has existed for more than 20 years, but it is now attracting attention as a mechanism for decentralization of electricity that enables, for example, the use of small-scale renewable energy power facilities in a region to secure electricity for each region in the event of a disaster.

In other words, if the microgrid functions well, it will be possible to promote the restoration of power outages caused by disasters and accidents on a regional basis, thereby speeding up the restoration process. It will also be possible to help each other, for example, by interchanging an electricity between regions to maintain supply and demand balance.

Challenges in expanding renewable energy

Japan now aims to achieve carbon neutrality by 2050. Similar initiatives are also taking place globally, especially in European countries and the U.S. Behind this is the pressing issue to reduce greenhouse gases, which are seen as the very cause of global warming and climate change.

To this end, it is important to stop thermal power generation, which emits a large amount of CO2 by burning fossil fuels. Then, there is an urgent need to turn renewable energy into the main power source.

You may think that we should increase solar power generation and wind power generation facilities to achieve this. However, it is not that simple. This is because both solar and wind power generation depend on the weather.

As mentioned earlier, balancing supply and demand leads to a stable supply of electricity. In that sense, thermal power generation and nuclear power generation were easy to control and maintain the balance.

Conversely, power generation from renewable energy sources is difficult to control, and the supply-demand balance may collapse rapidly, increasing the possibility of blackouts and long-term power outages. In order to turn renewable energy into a major power source, we must overcome these challenges.

However, behind these challenges are the power networks that have been built on easily controlled power generation systems.

In this sense, the development of microgrids and inexpensive large storage batteries, which have attracted attention as a result of disasters, is also important for expanding renewable energy, which will lead to new power networks for the next generation.

On the other hand, it is important for us as consumers to strive to save electricity on a daily basis.

In recent years, there has also been a system called Demand Response, which is an incentive system for requesting cooperation in saving electricity. While using such systems, it is our challenge to shift our awareness to the fact that we should not use electricity casually as in the past.

If such awareness is raised, for example, while the purpose of installing solar panels in each house has been to sell electricity, in the future, households will install solar panels as a self-sufficient power generation facility, and this may become the norm. It will be the smallest unit of a microgrid.

In fact, net-zero energy houses (ZEH) have been developed by house manufacturers.

If we reduce electricity consumption, the electric power companies will have to reduce the amount of electricity generated in order to balance supply and demand.

This will lead to the realization of carbon neutrality and a net-zero energy society, and will also lead to making the environment in which we live and the planet sustainable. In the end, we ourselves hold the key.

* The information contained herein is current as of August 2023.
* 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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