This disaster may have its root causes in the history of nuclear development in Japan. Nuclear scientists failed to take the initiative in peaceful use of nuclear and lost the opportunity of making basic researches prior to the commercial introduction of nuclear power generation. Otherwise, safety issues could have been handled with greater care and “nuclear safety myth” could not have prevailed.

Today, the discussion is ongoing on how to position nuclear in the Japanese energy mix. Purely from economic viewpoint, due to the energy reality of Japan, it might be extremely difficult to sustain its economy without nuclear at least in short and medium term. However, the public opinions are divided with the vast majority in favor of zero-nuclear or decreased nuclear dependency.

In this context, employing an energy-economic model, an attempt was made to analyze Japan’s power generation mix in 2030 under possible nuclear scenarios and assessed the role of nuclear energy in its energy mix. A technical implication taken form this analysis is that, if intermittent renewables such as solar and wind may largely diffuse in power grid replacing nuclear power, output fluctuation from high penetration level of these energy sources will be comprehensively accommodated by quick load following treatment by natural gas combined cycle, coal-fired power and pumped-storage hydro. Accordingly it will be important to coordinate and optimize multiple measures dynamically, together with technological innovation, for the treatment of the intermittency of renewables.

A newly born “energy democracy” in the post-Fukushima era will have impact on the government’s decision on the future energy mix expected early in autumn. Whatever the decision might be, the Japanese energy structure has already started to change towards further energy saving and efficiency. This will ultimately lead to the development of “a new energy model”, which will benefit all over the world.