Japan's Seventh Energy Plan Bets on Renewables and Nuclear Together. Its Weak Spot Is the Thermal Bridge

On 18 February 2025 Japan's Cabinet approved the Seventh Strategic Energy Plan, the government's framework for energy policy to fiscal year 2040. The plan sets indicative shares for the electricity mix in 2040 of 40 to 50 per cent renewables, around 20 per cent nuclear and 30 to 40 per cent thermal power. Within renewables it envisages 23 to 29 per cent from solar, 4 to 8 per cent from wind, 8 to 10 per cent from hydro, 1 to 2 per cent from geothermal and 5 to 6 per cent from biomass.

It was approved alongside Japan's new nationally determined contribution, which targets a 73 per cent cut in greenhouse gas emissions by fiscal year 2040 from 2013 levels, and the GX 2040 Vision for green transformation of industry. Earlier plans spoke of reducing dependence on nuclear power as much as possible. For more than a decade, Japanese energy planning assumed stable or declining power demand, as population fell and efficiency improved. Every additional terawatt-hour must come from low-carbon sources if emissions are to fall.

A share of around 20 per cent for nuclear in 2040 is ambitious. Japan's nuclear output has recovered only partially since the Fukushima accident in 2011. There is a reasonable case for restarts, which provide low-carbon power from existing assets at relatively low cost. A renewables share of 40 to 50 per cent is a large step from today's level. Solar is expected to provide the largest share, but Japan's suitable flat land is limited, and the best sites have already been used.

Offshore wind is the main growth area, but Japan's programme has faced difficulties. Japan's grid is divided into regional areas, with two different frequencies, 50 Hz in the east and 60 Hz in the west, and limited interconnection between them. The plan's 30 to 40 per cent for thermal power is where we see the most important gap. The Seventh Strategic Energy Plan moves Japan towards a pragmatic, all-of-the-above approach to low-carbon power, with a renewed commitment to nuclear and a large expansion of renewables.