Can renwable power generated in Japan meet the energy demand in Japan?

Ultimately, energy demand needs to be fulfilled by renewable power in a sustainable society.
In the case of Japan, is it possible to meet the energy demand only by utilizing renewable energy?

To consider the balance between the demand and supply of energy, the following two figures need to be addressed.

• The amount of enegy that is consumed in Japan
• The amount of renewable enegy that can be generated in Japan

How much of energy is consumed in Japan?

In Japan, Agency for Natural Resources and Energy under Ministry of Economy, Trade and Industry (METI) keeps track of energy-related things. It publishes "Statistics report" with the latest version today of 2019. According to this report, the primary energy amounts to 1.9*10¹⁹ [J].^[1]

Among this primary energy consumption, the electric power accounts for 3.3*10¹⁸ [J],^[1] which corresponds to approximately 930 billion [kWh] (= 3.3*10¹⁸ [J] / 3600 [J Wh^-1] *10^-3 * 10^-8). The statistics prioer to 2018 is summarized in a page of Agency for Natural Resources and Energy:^[2] In late 2000s, the electric power reacheed the highest of approximately 1,000 billion [kWh], but since then it has been decreasing on 2010s.

How much of renewable energy can be generated in Japan?

Then, let's see the total amount of renewable energy that can be generated in Japan.

Renewable energy comprises various types including solar, wind, geothermal; and each has its own best places to be implamented (see Issues associated with renewable energy utilization). Ministry of the Environment in Japan evaluated and summarized the potential renewable energy generation, and has developed a system named REPOS.^[3] The data has been summarized in a report of the Ministry,^[4] stating that the total renewable energy that can be "potentially" generated is 7,286 billion [kWh].

Taken together, in Jpan renrewable energy supply can be eight (8) times larger than the electric power demand.

Even if we consider not the total electric power but the total primary energy, this value of 7,286 billion [kWh] corresponds to 2.6*10¹⁹ [J] (= 7,286 billion [kWh] * 3600 [J Wh^-1] *10³ * 10⁸) that is actually greater than the annual primary energy consumption of 1.9*10¹⁹ J.^[1]

The, we can live just with renewable energy in Japan?

One may consider that, if these figures are correct, we can live just with renewable energy in Japan. However, we have to remember that these are just "potential" amount. There are technical, political, and economic barriers to be overcome in order to make ful use of the potential value. In fact, the Ministry also mentioned a renewable energy of 2,618 billion [kWh] likely as a potential value taking into account the economics.^[4] This value is apparently smaller than the primary energy demand in Japan...

In addition, when using the energy in forms other than electricity (such as heat), there exist losses associated with the energy conversion. Therefore, the energy that we can actually use can be even lower. To safely meet the energy demand, it is really needed to import energy from overseas.

References

1. 経済産業省 資源エネルギー庁, “総合エネルギー統計”, https://www.enecho.meti.go.jp/statistics/total_energy/results.html#headline2 (accessed on 2022/02/03)
2. 経済産業省 資源エネルギー庁, “第4節 二次エネルギーの動向”, https://www.enecho.meti.go.jp/about/whitepaper/2020html/2-1-4.html (accessed on 2022/02/04)
3. 環境省, 再生可能エネルギー情報提供システム[REPOS（リーポス）], https://www.renewable-energy-potential.env.go.jp/RenewableEnergy/ (accessed on 2022/02/04)
4. 環境省, “環境省地球温暖化対策課調査 わが国の再生可能エネルギー導入ポテンシャル”.