Combined output is seen at 1 million kilowatts, the equivalent of one nuclear reactor. The overall cost is estimated at 300 billion yen ($2.93 billion), with the facilities slated to go online as early as 2020. The government may provide financial assistance.

Plans call for building on the sites of existing fossil-fuel power plants in Iwaki and Hirono. Mitsubishi Heavy Industries and Mitsubishi Corp. will each take a 40%-plus stake in a special-purpose company that will be set up to run the plants, with Mitsubishi Electric owning 10%. Tokyo Electric Power Co. will hold a stake of less than 10%.

The interests of Tepco, which needs more fuel-efficient facilities but is short of money, align with those of the Mitsubishi group, which wants to build a track record in cutting-edge technologies to expand its power business abroad. Most of the needed funds will be procured through project financing. Tepco will run the plants and buy electricity generated at the facilities.

The plants will employ integrated gasification combined-cycle technology, in which exhaust heat from power-generating gas turbines is reused to produce even more electricity. Power output will be about 20% higher than conventional coal power plants using the same amount of fuel. Another advantage is that Tepco will be able to use cheaper, low-grade coal.