 Four 750-kilowatt Fincantieri Isotta Fraschini diesel generators provide 3 megawatts of electrical power to power the ship systems.The Congressional Budget Office estimates that fuel will account for only "8 percent to 18 percent" of the total life-cycle costs for "Freedom".Senator Jeff Sessions of Alabama has called the report into question and has suggested that "Independence", built in his state, would be more fuel efficient and that less frequent refuelings would affect military operations beyond the cost of fuel.