Evaluating options for the future energy mix of Japan after the Fukushima nuclear crisis

The Fukushima nuclear accident in March 2011 has increased social and political reluctance to embrace nuclear power in Japan (and elsewhere). The Japanese government has thus been considering four possible future energy mixes, including a nuclear-free pathway, and three others with 10%–35% nuclear supply coupled with a larger proportion of renewable energy and fossil fuels to replace nuclear. Here we use multi-criteria decision-making analysis (MCDMA) to assess the potential negative economic (levelised cost of electricity, and energy security), environmental (greenhouse-gas emissions, land transformation, water consumption, heated water discharge, air pollution, radioactive waste, and solid waste) and social (safety issues) impacts of the four proposed pathways to determine which scenario most holistically minimises adverse future outcomes. The nuclear-free pathway has the highest overall potential for adverse outcomes (score=2.49 out of 3), and the 35% nuclear power supply option yielding the lowest negative impact score (0.74) without weightings. Despite some sensitivity to the choice of criterion weights, our analyses demonstrate clearly that from an empirical perspective, a nuclear-free pathway for Japan is the worst option to pursue. We recommend that MCDMA methodology we used for Japan can be applied to other countries to evaluate future electricity generation scenarios.

► A nuclear-free pathway will have greater negative impacts than the pre-Fukushima-crisis energy situation.
► To meet the GHG targets, >35% nuclear power supply for electricity will be essential.
► To minimise loss of life, fossil fuels should be avoided rather than nuclear power.
► Despite projected restoration costs, more nuclear power will lead to cheaper electricity costs.
► The less that nuclear power is used, the lower will be the sustainability of Japan's energy system.