Nuclear power has always been a fraught issue for green-minded people, with its combination of near-zero greenhouse emissions and scary toxic waste — not to mention the potential for disastrous meltdowns.

Now, Reuters reports that two of nuclear’s biggest supporters, France and Japan, have essentially switched sides in the debate. In the wake of last year’s Fukushima disaster, Japan is phasing out its nuclear plants and increasing spending on renewable energy, while France plans to reduce its dependence on nuclear.

By the 2030s, Prime Minister Yoshihiko Noda says the island nation — which produced more than 10 percent of the world’s nuclear power in pre-Fukushima years — will be out of the nuclear industry. At the same time, it plans to triple the share of renewable resources so they contribute 30 percent of its energy needs.

French president Francois Hollande promises to cut the share of nuclear power in the country from a whopping 75 percent today to 50 percent by 2025. Hollande also called for a 40 percent cut in the European Union’s carbon dioxide emissions by 2030 and a 60 percent cut by 2040.

Weighing in on the other side of the debate, the International Energy Agency (IEA) warned that it may be impossible to fill the gap left by nuclear power entirely with renewables and said the nations will inevitably end up using more fossil fuels. (Incidentally, the website of the journal Nature has an interesting set of charts showing IEA projections on fuel mix through 2035, as well as some other useful data.)

Luis Uriza of Bain & Co. told Reuters that natural gas is the most likely fuel to fill the void, which Japan already imports as a major energy source.

Germany, one of the most aggressive pursuers of alternative power, has backed away from nuclear since Fukushima, but it is still gets a large share of its power from fossil fuels.

Photo of nuclear power plant in Cattenom, France, courtesy of Stefan Kühn/Wikimedia