FOR decades few countries were more evangelical about the charms of nuclear power than Japan, and until the earthquake and tsunami in March last year nuclear plants generated almost 30% of its electricity. Yet by May 5th at the latest, the last of Japan’s 54 nuclear reactors will be switched off. Besides those permanently disabled in the Fukushima disaster, the rest have been taken offline for “routine maintenance” and kept that way because there is not enough public confidence in their safety to restart them. In all, that will mean about 50 gigawatts of nuclear capacity has been snuffed out, for the time being. To get a sense of the scale of this, imagine Tokyo (whose peak requirement is around 50GW) without power: no air conditioning, no bullet trains, no neon lights.