But it is now more expensive to build new transmission lines and other grid hardware, making battery storage potentially more attractive. "Cost is given as the reason that energy storage is not widely used on the grid," the researchers wrote, and cost reductions in lithium ion batteries—thanks to potential wide-scale deployment in electric vehicles—may change that equation. Big lithium ion batteries may soon be made very inexpensively and in large volumes, making them finally cheap enough for widespread grid storage applications, along with other possibilities. "Electric vehicles themselves can act as storage," Kamath notes. "Of course, the owner of the vehicle would have to agree to that."
Already, power company AES has opened the nation's largest battery installation in Elkins, W. Va. More than 30 megawatts-worth of lithium ion batteries from A123 Systems have been hooked up to the company's 98 megawatts-worth of GE wind turbines to ensure a steadier power output.
There is already a technological leader in the cheap storage area, however: pumped hydro, which accounts for 99 percent of the 127,000 megawatts–worth of electricity storage in use today worldwide. Its spread is limited only by geography, geology and concrete. And, ultimately, more advanced storage options—whether batteries or flywheels—may be undone by another competitor: combined-cycle turbines that employ natural gas and can be started up in seconds. "We need new technologies and techniques to make batteries lower cost, longer-lived and more efficient," Kamath says, especially to compete with fossil fuel–fired alternatives.