Columns that reveal the world
- Getting up close and personal with the researchers -

What does the word "energy" actually mean, a word we use often in our daily lives? In physics, this word means "the power to do work," and in economics, it means "goods that have the ability to do work." Energy is needed to move things, generate heat, and create light. The energy resources that produce this energy include fossil fuels such as coal, crude oil, and natural gas, nuclear power, and energy obtained directly from nature such as the sun, wind, water, and geothermal energy (also called "primary energy").

Our convenient lives are made possible by the use of secondary energy such as electricity, gasoline, and city gas, which are produced by converting and processing these fuels. A stable supply of both of these energy sources is essential for a country's economic activity and the prosperity of its people, but Japan, which lacks natural resources, has no choice but to import many of its energy resources. For this reason, we have chosen the energy we use while taking into consideration various factors such as the world and Japanese economies, social situations, and the external environment.

Let's think back to how we used to live. A generation ago, most household heating appliances were kerosene stoves or gas fan heaters, but I think there are few households in cities that use kerosene stoves these days. Many things, such as air conditioners and floor heating, use electricity. Electricity, which is convenient and environmentally friendly (no need for ventilation, etc.), replaced petroleum products such as kerosene and city gas. In this way, electricity has become indispensable in our lives. And in order to generate huge amounts of electricity, the energy resources used at power plants have shifted from petroleum to natural gas and atomic power.

So why did the energy shift from oil to nuclear power occur?

Its origins can be traced back to the oil crisis of the 1970s. At the time, 80% of Japan's electricity production was dependent on oil, so the development of alternative energy sources was urgently needed, and the government focused on shifting to atomic, natural gas, and renewable energy. However, the cost of equipment for renewable energy, such as solar power, was not reduced enough to allow for its widespread use all at once. On the other hand, natural gas must be transported by ship from the producing country, as Japan is an island nation, and it requires huge investments in equipment and technology, such as cooling the gaseous natural gas to make it liquid and reducing its volume to 1/600 before transporting it. Later, in the 1990s, the environmental issue of global warming had to be taken into consideration, and it was necessary to use energy while also reducing CO2 emissions, so the decision at the time was made to expect a certain role for atomic energy, which produces large amounts of electricity using limited uranium resources.

In the 1990s, the global trend toward deregulation led to the issue of improving management efficiency. Electricity prices in Japan were higher than in other developed countries, and there were concerns that this was one of the factors driving up production costs for companies. In response, introducing the principle of competition to produce electricity more efficiently became one of the important goals of energy policy.

Following this trend, the introduction of nuclear power generation progressed. However, as of fiscal 2010, before the Great East Japan Earthquake occurred in March 2011, nuclear power accounted for just under 30% of the fuel input used to generate electricity, split equally between coal and natural gas. As a result, Japan became the world's third largest country in terms of nuclear power generation. The remainder was hydroelectric power and oil, with oil accounting for less than 10% at its lowest, so it can be said that the goal of "de-oilizing" electricity production had been achieved.

The dangers of nuclear power plants were exposed by the Great East Japan Earthquake that occurred in March 2011. In response, many people became interested in promising alternative energy sources, and hoped for the promotion of renewable energy.

Some people may think, "Since there have been no large-scale power outages even though all nuclear power plants are in operation, it might be okay to just get rid of nuclear power plants," but because Japan currently relies heavily on fossil fuel power generation, it is not able to use energy in a way that takes global warming into consideration.

What is required for next-generation energy resources is not only "ensuring energy security" - that is, a stable supply of energy resources regardless of the political situation overseas, "high economic efficiency," and "environmental compatibility," but also "safety and security" in the event of unforeseen circumstances such as disasters.

So, let's take a look at whether the renewable energy sources that are currently attracting attention can meet these conditions.

Renewable energy sources come from natural sources such as sunlight and wind, so they are excellent in terms of "ensuring energy security," "environmental compatibility," and "safety and security." However, as shown in the table below, when you compare the "energy density" (how much energy can be produced per 1,000 m2) with other forms of energy, you can see that it is overwhelmingly low density and sparse. It is said that if you were to generate the same amount of electricity as one nuclear power plant, you would need a land area about three times the size of the circle inside the Yamanote Line to generate that much electricity using wind power. Because Japan is an island nation, there are very few places to install wind power generation facilities on land.

In addition, the "capacity utilization rate," an indicator that is closely related to power generation costs, is low for renewable energy, at only 12-14% for solar power generation and only about 20% for wind power. All power generation facilities undergo regular inspections, so the utilization rate never reaches 100%, but when you compare it to the 70% utilization rate of thermal power plants, you can see how low the utilization rates of solar and wind power are. In addition, they are dependent on weather and wind conditions, and cannot generate electricity stably 24 hours a day. In other words, it can be said that renewable energy has many challenges to overcome in terms of "economic efficiency" and "output stability."

Considering these circumstances, renewable energy will not become the energy of dreams unless there is further technological development. Until we find an energy source that can guarantee "energy security," "high economic efficiency," "environmental compatibility," and "safety and security," the only way to maintain our current lifestyle is to diversify risks by using a variety of energy sources.

However, when it comes to balancing energy usage, we are no longer in an era where it is up to the government alone to push for it; rather, we are in an era where each and every citizen must seriously consider and make a choice.

How much energy do we use in a day? We wake up in the morning, use various home appliances to get ready to go out, then travel by train or car, and once inside a building we use the escalators, elevators, air conditioning and lighting. The food we eat and the clothes we wear also consume a lot of energy before they reach us, through production, transportation and sale. However, we are able to make our entire lives possible without even realizing that we are consuming energy. Perhaps it is time to take an interest in this kind of lifestyle and give it some serious thought.

(Published in 2016)