The earthquake and tsunami last year resulted in 15 of its 17 nuclear plants being closed, forcing Tepco to turn to thermal stations for power generation.

BBC: Tepco raises electricity prices for corporate clients

This was after the leak at the Fukushima nuclear plant resulted in other nuclear plants being shut, forcing it to rely on traditional thermal power stations to produce electricity.

BBC: Tepco seeks more aid as Fukushima clean-up costs rise