Fighter jets scream over Columbus Air Force Base, a sprawling military facility in eastern Mississippi that is especially busy these days training aviators for the war on terror. But for all the high tech aeronautics on display overhead, the bustling Air Force base often relies on an old-fashioned diesel generator to keep radar and communications humming and the jets from colliding. That’s because the region’s antiquated, overloaded power grid dishes out 25 blackouts a year, as well as another hundred or so voltage fluctuations that crash sophisticated flight simulators.
The solution-the world’s largest battery-is under construction nearby. Two cavernous steel tanks, each one 10 meters tall and 20 meters in diameter, will soon hold nearly four million liters of concentrated salt solutions, electrolytes that will be charged and discharged by 24,000 fuel cells in an adjacent building. At night this installation, known as a flow cell battery, will suck electricity from the grid and store the energy, which it will discharge during the day when power lines are strained. When blackouts strike-common in this tornado-prone region-the huge battery will keep the base humming for up to 24 hours.
This massive battery represents more than a backup power supply for an isolated military facility. It’s a bold experiment in large-scale electricity storage on the power grid-the aging maze of interconnected power plants and transmission lines that cover the country. Today’s grid operates with minimal storage, so at all times, electricity flows must exactly balance the power that’s being consumed. Partial solutions are available in a new class of digital switches that more efficiently deliver electricity during crunch periods (see “A Smarter Power Grid ,” TR, July/August 2001). But devices such as the Columbus flow cell, which is being built by the federally operated Tennessee Valley Authority and Swindon, England-based Regenesys Technologies, go one step further. By storing hours of electricity, flow cells offer, for the first time, the possibility of freeing the grid from the need to continuously balance production and consumption.
The implications of a newly flexible grid are immense. Sufficient storage capacity would relieve pressure to build new power plants and transmission lines, prevent regional blackouts, even speed the adoption of wind farms and solar panels by transforming intermittently produced power into steady reserves. Also, by dampening glitches and power spikes, the more flexible grid would provide the high-quality power needed for today’s sensitive electronic equipment. Problems ranging from blackouts to the voltage fluctuations that cause chaos in high tech manufacturing sap an estimated $119 billion from the U.S. economy every year, says Kurt Yeager, CEO of the Electric Power Research Institute, a utility-funded R&D consortium in Palo Alto, CA. This hemorrhage is just one indicator that power grid fundamentals need rethinking, he adds. “The world as we know it can’t continue. Prudent people would not wait for the lights to go out to do something about it. We’ve got to change the architecture of the grid,” he says.
The storage solution is coming, albeit slowly. About a dozen companies worldwide are developing and testing technologies capable of storing large amounts of electricity on the grid (see “Battery Power for the Grid,” table on last page). Over the past decade, for example, advanced battery systems have been demonstrated by Tokyo-based NGK Insulators at more than 30 sites in Japan. A smaller version of flow cell technology developed at the University of New South Wales in Australia and distributed by VRB Power Systems of Vancouver, Canada, will soon support power flows to a remote but growing community in southern Utah. And electricity distributors in California, Hawaii, and Denmark are eyeing Regenesys’s flow cell technology as a way to ease congestion and prepare their transmission networks for rapidly expanding flows of renewable energy. “Storage distributed around the grid would make the whole system more robust and more efficient,” says Ali Nourai, a technology consultant at American Electric Power in Columbus, OH, one of the largest electric utilities in the United States. “The need is there, the market is there, and the price is coming down,” he says. “In two to five years, storage will be all over the place.”