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Dr. Tsubokura's Radiation Lecture Vol.85

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

169. Japan’s low rate of energy self-sufficiency

Japan is one of the largest consumers of primary energy in the world, but our country lacks resources, such as oil and natural gas, and therefore has little energy self-sufficiency.

In Japan, a majority of the primary energy supply consists of fossil fuels from abroad, such as oil, coal, and natural gas, and the proportion of imported fuels has increased even more since the Fukushima nuclear disaster. The proportion of imported fossil fuels was 81% before the disaster, and it increased to 89% in 2016 due to thermal power plants’ increased power generation following the shutdown of nuclear power plants.

In 2016, Japan’s primary sources of power generation were mainly natural gas (40.4%), coal (33.3%), and petroleum (9.3%). Renewable energy, such as solar power (XX%), biomass (XX%), wind (XX%), geothermal (7.8%), and hydropower (7.5%) occupied small proportions. In addition, nuclear power’s proportion was only 1.7% at the time.

The electricity’s sources vary by country. For example, about 60% of Canada's electricity is generated by hydropower. In comparison, France generates 80% of its electricity by nuclear power, and renewable energy sources generate approximately 30% percent of Germany’s electricity.

The constitution of power sources in each country above differs from that of Japan. The type of electricity generation and the economic and social situation of neighboring countries must be determined to maintain balance.

170. Advantages and disadvantages of energy sources

Japan is one of the world’s largest consumers of primary energy, but our country lacks resources, such as oil and natural gas, and therefore has little energy self-sufficiency. Oil, coal, and natural gas account for over 80% of Japan’s total energy consumption, and the majority of the energy supply relies on imported fossil fuels.

To stabilize the country's energy supply, the power generated must match the energy consumption. However, electricity consumption varies with the season, day, and time of day. For example, daily activities in the morning lead to higher electricity consumption compared to at night, when everyone sleeps. Furthermore, when the outside temperature is hot or cold, energy consumption changes with the use of heaters or air conditioners. Therefore, the amount of power generated must be modified according to changes in power consumption throughout the day.

On the other hand, each power supply has advantages and disadvantages. For example, solar and wind power raises Japan’s energy self-sufficiency rate and does not emit carbon dioxide during power generation. However, their power generation is unstable and vulnerable to weather changes. Thermal power generation can easily adjust the amount of power generated, but it increases carbon dioxide emissions.

No single method of power generation that has only strengths or weaknesses. Furthermore, power generation costs vary for each power source, so people must consider what kind of energy to utilize.


The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, 25th March and 8th and 15th April 2018 was reproduced for MRIC Global under the author's permission.

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