Japan's shutdown of all its nuclear power plants leaves it with an energy gap, mostly being made up through greater use of costly imported LNG, coal and oil. Below are some details of the resource-scarce country's "green energy" options.
HYDROELECTRIC: Mountainous, rainy Japan relies on hydroelectric power for about 8 percent of its electricity. Having already dammed virtually all possible sites, smaller hydroelectric facilities offer limited potential. Hydroelectric is also unstable since it depends on rainfall and water levels, making it ill-suited to replace the huge and consistent power capacity provided by nuclear plants.
SOLAR: Current capacity is about 3.5 gigawatts (GW), less than 1 percent of total power generation. Installing solar power is relatively expensive, at 40 yen per kilowatt hour (kwh). Government feed-in tariff will require utilities to pay 42 yen/kwh.
WINDR: Japan has offshore wind power potential, mostly in northern Japan, though extreme weather poses a hazard. Current capacity is about 2.5 GW. Wind power turbines cost about 15-20 yen/kwh to install.
The government's new "feed-in" tariff to producers is 23.10 yen/kwh for wind power facilities of 20 KW or more and 57.75 yen for smaller ones. Installing small wind turbines on high-rise buildings and putting wind turbines offshore could help minimize use of scarce land.
GEOTHERMAL: Volcanic Japan, with its many hot springs, has potential for 23.47 GW of geothermal energy but most of it is in national parks or hot springs resorts and difficult to exploit. Current capacity is about 0.5 GW. Costs are similar to wind, at 15-20 yen/kwh. Feed-in tariff will be 27.30 yen per kwh for plants of 15,000 kilowatts capacity or more and 42 yen per KW hour for smaller plants.
BIOMASS/WASTE: Mostly from industrial and municipal waste. About 3.2 gigawatts of capacity. Costs are about 15-20 yen/kwh, with feed-in tariff between 13.65 yen/kwh-40.95 yen/kwh
OCEANIC: Using ocean currents, tides and differentials in sea water temperatures to generate power. Some use in Europe but Japan is still experimenting, with no commercial projects so far.