Japan’s restarted nuclear reactors in 20 months could produce 25-30% of world solar power

A total of ten Japanese nuclear power reactors are likely to have been restarted by the end of March 2019, according to the latest estimate by the Institute of Energy Economics, Japan (IEEJ). These restarts will help improve the country’s economy, energy security and environment.

So far five Japanese reactors – Sendai units 1 and 2; Takahama units 3 and 4; and Ikata unit 3 – have been restarted under new safety regulations. The IEEJ notes another seven units have already met these standards and are being prepared for restart.

The organization estimates that if restarts take place according to the current schedule – the “reference scenario” – by the end of FY2018, ten units could be restarted, generating 65.6 TWh of electricity annually and representing a 7% share of the country’s power generation mix. This compares with total nuclear output of 288.2 TWh and a share of almost 30% in FY2010, the year prior to the accident at the Fukushima Daiichi plant.

Its high-case scenario assumes a total of 17 units are restarted by the end of FY2018, generating 99 TWh annually, with spending on total fossil fuel imports decreasing by JPY700 billion (USD6.4 billion) relative to the low-case scenario where no more reactors beyond the current five are assumed to restart, producing 32 TWh. In the high-case scenario, the average electricity unit cost is lowered by about JPY453/MWh (USD4 per MWH) and energy-related emissions decrease by 45 million tonnes CO2.

By the end of 2016, cumulative solar photovoltaic capacity reached about 302 gigawatts (GW). In general one terawatt hour per year is generated by each gigawatt of installed solar power. Six to eight terawatt hours per year is generated from each gigwatt of nuclear reactor. The solar power generation was about 300 terawatt hours in 2016. It was probably less as the 76 GW installed in 2016 started operating over the course of the year and did not generate power for the full year.

If all of the Japan’s nuclear reactors (that have not been retired) were restarted then they would generate about 80% of the 2016 world’s solar power.

With ten reactors in operation, compared with none, real GDP expands by JPY500 billion (USD4.5 billion), the self-sufficiency ratio increases by 2.9 percentage points and energy-related carbon dioxide emissions fall by 2.7%. Electricity unit cost should decrease by JPY300 per megawatt-hour (USD2.70 per MWH), compared with no reactors being restarted beyond the current five.

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