In 2007, Japan had about 177 GW of conventional thermal electric generating capacity. According to Japan Electric Power Information Center, there are currently 60 thermal power plants, and 5 more are under construction: 2 using LNG and 3 using coal for generation. The country's aging oil-fired power plants are used primarily as extra capacity to meet peak demand, and less than 10 percent of electricity produced currently is oil-generated. The number of natural gas-fired power stations is increasing in Japan and roughly 30 percent of electricity is natural gas-fired. Coal remains an important fuel source and accounts for roughly 25 percent of electricity generation. Domestic coal production came to an end in 2002 and Japan imported 206 million short tons in 2008, for which Australia was the main supplier. New, clean coal technologies are being pursued in the power sector, however, in efforts to meet environmental targets.
Japan currently has had 54 operating nuclear reactors with a total installed generating capacity of around 49 GW, making it the third-largest nuclear power generator in the world behind the United States and France. EIA preliminary data shows that Japan produced 244 BKwh of nuclear-generated electricity in 2008. The government plans to increase nuclear's share of total electricity generation from 24 percent in 2008 to 40 percent by 2017 and to 50 percent by 2030, according to the Ministry of Economy, Trade and Industry.
http://www.eia.doe.gov/countries/cab.cfm?fips=JA
Natural gas is commonly used and pipeline connected around their country.