Before a massive earthquake and tsunami triggered multiple meltdowns at the Fukushima Daiichi facility, Japan's 54 nuclear power plants provided more than 30 percent of the nation's electricity. A little more than a year later that number will be soon be reduced to zero:

Japan will within weeks have no nuclear power for the first time in more than 40 years, after the trade minister said two reactors idled after the Fukushima disaster would not be back online before the last one currently operating is shut down.

Trade Minister Yukio Edano signalled it would take at least several weeks before the government, keen to avoid a power crunch, can give a final go-ahead to restarts, meaning Japan is set on May 6 to mark its first nuclear power-free day since 1970.

It's not good news, of course, to see Japan's nuclear power capacity replaced by carbon-emitting coal and gas. But if you had asked the Japanese before the disaster whether such a massive and sudden shift in power generation was even feasible, I'm pretty sure those in charge would have said no.

Makes me wonder how impossible it would really be for the US to shift, say, 30 percent of its own generating capacity to renewables in a decade or so? You know, if we really wanted to.