We use the word “energy” daily, but what does it mean? “Energy” is “the capacity to do work” in physics and “goods with the ability to do work” in economics. Energy moves objects, generates heat, and makes light. Resources of this energy comprise fossil fuels (coal, crude oil, natural gas, etc.), nuclear power, and resources derived directly from nature (sunlight, wind, water, geothermal heat, etc.). The energy harvested from these resources is also called “primary energy.”
These primary energy resources are then converted or processed into electricity, gasoline, city gas, and other secondary energy resources used for sustaining our convenient life. Therefore, the stable supply of the both primary and secondary energies is essential to maintain a country’s economic activities and people’s prosperous lives. However, Japan has a lack of energy resources and has to rely on imports for many of them, and this has necessitated Japan making energy choices that are in line with global and domestic economic developments, the social situation, the external environment, and various other conditions of the times.
Let us look back at our past lives. Many people used to use oil or gas for their heaters, but oil and gas heater users are rapidly becoming a minority particularly in urban areas as those heaters have been replaced mainly by air conditioners, electrical floor heating, and other devices that use electricity. Electricity, which is superior in terms of convenience and environmental performance (no ventilation required, etc.), has taken the place of kerosene and other oil products and city gas. Electricity has thus become indispensable for our lives. This trend has accompanied the need to produce a vast amount of electricity, and to meet this need, energy resources used at power plants have also shifted from oil to natural gas and nuclear power.
What has caused a shift from oil to nuclear and other energy resources?
It all started when the oil crises occurred in the 1970s. At that time, Japan was relying on oil for 80% of its electricity production and under great pressure to find an energy resource that can replace oil. The government focused on nuclear power, natural gas, and renewable energy. However, renewable energy resources, as typified by photovoltaic power, were difficult to introduce rapidly due to their high facility costs. Natural gas had to be transported by ship from producing countries as Japan is surrounded by seas, necessitating a huge amount of investment in equipment and technology, such as those used for cooling and converting natural gas in a gaseous state into liquid to reduce the volume up to 1/600th for transportation. Furthermore, consideration of the environmental issue of global warming became important in the 1990s, requiring energy users to achieve reduction of CO2 while consuming energy. These circumstances are the background to the decision to adopt nuclear power, which was expected to play a certain role as an alternative to oil due to its ability to generate a huge amount of energy from a small amount of uranium.
The 1990s also saw the increase in operational efficiency become an important issue amid the global trend of relaxing regulations. Because of a concern that electricity rates in Japan may be higher than those in other developed nations and partly responsible for the high production costs of companies, Japan’s energy policy started to focus on more efficient power production based on the principle of competition as a major goal.
These trends prompted the introduction of nuclear power generation in Japan. In fiscal 2010, before the Great East Japan Earthquake occurred in March 2011, nuclear power accounted for a little less than 30% of all fuel input for electricity generation, and nuclear power, coal, and natural gas became the three most important sources of energy, each having an approximately one-third share in electricity generation. Japan thus became the world’s third largest owner of nuclear power plants. The other major resources were hydropower, etc. and oil, but the share of oil fell—below 10% at the lowest—and it can be safely said that Japan achieved its goal of moving away from relying on oil for electricity production.
The Great East Japan Earthquake in March 2011 revealed the vulnerability of nuclear power plants. This drove many people to take an interest in what could be an alternative energy source and expectations for the use of renewable energy to be promoted more vigorously.
There are probably also many people who consider that nuclear power plants may not be necessary because no large-scale power outage occurred even when the operation of all the nuclear power plants in Japan was suspended after the disaster. However, Japan is now relying on thermal power generation to compensate for the loss of nuclear power generation, making the nation unable to switch to the kind of energy that will contribute less to global warming.
A next-generation energy resource must be worry-free and safe even in a contingency, such as a natural disaster, as well as achieve energy security to assure uninterrupted availability of energy resources irrespective of overseas political situations, have high economic efficiency, and maintain compatibility with the environment.
Let us check whether renewable energy, which is expected to be a viable alternative to nuclear power, satisfies all these conditions.
Since renewable energy is sourced from nature, such as the sun and wind, it achieves energy security and is compatible with the environment and worry-free and safe. However, when it comes to energy density (how much energy can be derived from each 1,000-square-meter area of power plant), as the table below shows, renewable energy is far lower in density than any other energies. To produce power equivalent to that of one nuclear power plant, it is said that a wind power farm requires about three times the area within the Yamanote loop train line. Because Japan is an island country, the space in which onshore wind power farms can be built is very limited.
Renewable energy is also low in capacity factor, an indicator that is closely related to power generation costs, with photovoltaic power being 12 to 14% and wind power being around 20%. While 100% capacity factor is impossible because every power generation facility must be stopped temporarily for regular inspections, etc., the capacity factor of photovoltaic and wind power plants is still considerably lower than that of thermal power plants at 70%. Furthermore, renewable energy is greatly affected by weather and wind conditions and is unable to supply electricity stably for 24 hours a day. All these mean that renewable energy has many problems to address, particularly in terms of economic efficiency and output stability.
Considering these restrictions, renewable energy cannot be a dream energy source without further technological development. In order to maintain our current lives, we have no choice but to use various energy sources to disperse risks until we discover an energy resource that excels in energy security, economic efficiency, environmental compatibility, and safety.
Promoting this balanced way of using energy resources is something that should not be left solely to the government alone. We are now in an era where each one of us must seriously think about and choose what energy resources should be used.
Think of how much energy we are using each day. After getting up in the morning, we use various kinds of home appliances to prepare for going out, move by train or car, and use escalators, elevators, air conditioners, and lights in buildings. The food we eat and the clothes we wear also consume a significant amount of energy during the process of production, transportation and sales before they reach us. However, we are hardly aware of how much energy we are consuming for everything in our everyday lives. We need to have concerns about this way of leading our lives and ponder what we should do.
(This column is as of 2016.)