A factor of five reduction in cost will be necessary if batteries are to become commercially viable for grid-scale electricity storage, according to the head of the Department of Energy’s battery research center. George Crabtree, director of the Joint Center for Energy Storage Research (JCESR) at Argonne National Laboratory, told a panel discussion that center researchers are evaluating several battery technologies, with the exception of batteries based on lithium ions, which are viewed as incapable of attaining the needed improvements. Lithium-ion technology has been improving its cost-effectiveness, but at a rate of 5–10% a year.
Currently available grid-scale storage batteries are about five times more expensive than pumped-storage hydroelectricity, which is the leading method for balancing demand, Crabtree said. First deployed in the 1890s, pumped-storage hydroelectricity entails the use of off-peak electricity to pump water to higher elevations. At times of peak demand, the water is released to drive turbines and generate electricity. Storing electricity in today’s batteries is also five times more expensive than generating it at a power station fueled by natural gas.
Three beyond-lithium-ion battery concepts are being investigated at JCESR: replacing singly charged lithium ions with doubly charged ions such as magnesium, or triply charged ions such as aluminum, in multivalent intercalation; replacing intercalation of the working ion at the anode and cathode with higher-energy covalent bonds in chemical transformations; and replacing crystalline electrodes with fluid electrodes in nonaqueous redox flow. Adding the option of using solid or liquid electrolytes yields at least 18 conceptual designs for beyond-lithium-ion batteries, according to a paper, Physics of Sustainable Energy III: Using Energy Efficiently and Producing It Renewably, Crabtree authored for the AIP conference proceedings. Some 20–30 materials are candidates for implementing those designs, he said.
The three energy storage concepts that JCESR pursues: replacement of singly ionized lithium by doubly chargedions such as magnesium or triply charged ions such as aluminum in multivalent intercalation (top panel); replacement of intercalation of the working ion at the anode and cathode with higher energy covalent chemical bonds in chemical transformation (middle); and replacement of crystalline electrodes with fluid electrodes innon-aqueous redox flow (bottom).
Fast, flexible bulk energy storage that can buffer and smooth fluctuations and mismatches of power will be as fundamental to the smart grid as power transformers and circuit breakers, said Jeffrey Taft, chief architect for electric grid transformation at Pacific Northwest National Laboratory. He was speaking at a 17 March hearing of the Senate Energy and Natural Resources Committee. Because on the grid, the supply of power must be evenly matched with demand at all times, smoothing will be required to accommodate increasing amounts of solar and wind generation, which are intermittent sources. Today’s best solar technologies can produce only 20% of their potential capacity, and even in the windy plains, wind generation can achieve just 33% of its capacity, said Argonne National Laboratory director Peter Littlewood to lawmakers.
“Across our energy economy, effective storage of energy holds the key to the flexible energy sourcing and delivery required to diversify our energy portfolio, renovate our energy infrastructure, and alleviate the growing environmental costs and risks of continued reliance on fossil energy as our primary energy source,” Littlewood said. “For the grid, advanced battery technologies are the key to storing energy from intermittent sources so we can release it later when we need it.”
“Energy storage via battery technology has long been viewed as a game changer for the electricity industry, if it could be implemented cost-effectively,” testified Lisa Barton, executive vice president for transmission at American Electric Power (AEP). In 2006, AEP was the first utility in North America to deploy a megawatt-scale sodium–sulfur battery. In 2009, AEP installed two 2.4-MW NaS batteries in Presidio, Texas, to provide transmission backup in the event of a transmission line outage. Presidio is a small, remote community bordering Mexico along the Rio Grande. Previously, when Presidio’s line encountered an outage, the town had an immediate blackout and its only alternative electricity came from Mexico, Barton said.
In most circumstances, however, the cost of energy storage currently exceeds what the market will support, Barton said. Storage costs need to come down, and that can only happen with increased R&D and greater market penetration. Deployment of energy storage can face regulatory barriers, she added.
Committee chair Lisa Murkowski (R-AK) said that broad energy legislation being drafted by the committee will likely address energy storage and other grid modernization components.
