The new Japanese green tariffs require utility companies to purchase electricity from renewable sources, such as wind, solar, biomass, geothermal and different forms of biomass. Japan's government views this requirement as a positive step towards reducing its historic reliance on nuclear power and thereby mitigate against a potential future "nature+nuclear" national catastrophe a la Fukushima.
Japan only generates about 1% of its energy from renewable sources at present, but analysts predict that the country should unlock at least 30 billion USD in fresh renewable energy investment by means of these new tariffs. It will be interesting to watch how feed-in tariff policies evolve in the USA and other major economies -- much work still needs to be done in order to reduce our global dependence on greenhouse gas emitting fossil fuels.
Cheers -- Jon