Tokyo Electric Power Co. almost quadrupled its coal consumption in September from a year earlier after starting two units that burn the fuel.

Tepco used 711,000 metric tons of coal last month, up from 184,000 metric tons in September 2012, according to data on its website. Fuel oil consumption fell 56 percent and use of crude oil was down 69 percent, the data show.

With all reactors shut down after the disaster at the Fukushima No. 1 plant started in 2011, Tepco and other electric companies have been boosting use of coal, a cheaper source for power generation than oil and gas, to make up for the absence of nuclear output. Tepco began trial operations in April at two coal-fired units with combined capacity of 1,600 megawatts.

Coal-fired power generation costs ¥9.5 per kilowatt hour, while liquefied natural gas costs ¥10.7 and oil runs ¥36, a government panel estimated in a report in December 2011. The cost for nuclear power is at least ¥8.9 per kwh, the panel said.