Batteries vs. alternatives for storing energy

Electric utilities need quickly-available sources of power for supplying expected and unexpected peak loads. Among such useful sources have been the energy stored in water by pumping it to elevated storage reservoirs, in air compressed into underground chambers and in batteries. A new power source, base-load nuclear and coal-fired steam plants generate off-peak energy for recharging the depleted storage facility. The aero-derived gas turbine challenges the economics of these traditional energy-storage means. These turbines have been designed for aircraft where quick startup, rapid change in output power, and high reliability are essential. With a 1426°C (2600°F) turbine inlet temperature the available efficiencies are 42 percent in simple-cycle operation and 60 percent in a combined-cycle power plant. A recent 84-MW natural-gas-burning peak-power plant cost $204 per kW. Pacific Gas and Electric´s Helmes River pumped-hydro plant had cost $656 a kW. These combined-cycle gas turbine plants, with their low manpower requirements, are producing power that costs less than power from nuclear power plants. Here, the authors examine the performance and economics available from these new power sources