The nation's biggest power utilities are pushing ahead with plans to spend more on new turbines to improve the efficiency of their gas-fired power plants in an effort to lower fuel bills amid a protracted debate over the role of nuclear power.

Chubu Electric Power Co. signed an agreement with General Electric Co. on Tuesday to upgrade eight turbines at a gas-fired plant in Joetsu, Niigata Prefecture. Tokyo Electric Power Co., the nation's biggest utility, is replacing eight turbines at its 3,352-megawatt gas-fired facility in Yokohama, and Kansai Electric Power Co. in March completed installation of some of the most efficient turbines in the world at its Himeji No. 2 plant in Hyogo Prefecture.

The upgrades occur against the backdrop of rising electricity prices — power bills in Japan have increased about 15 percent since the March 2011 Fukushima reactor meltdowns — and a squeeze on profits at the utilities, which were forced after the nuclear disaster to rely on more expensive fossil fuels for power generation. Tepco estimates savings of as much as ¥8 billion a year once all the turbines at its Yokohama plant are replaced by January 2018.