The high cost of batteries has made them impractical for storing energy from wind and solar or providing back-up power on the electricity grid. Now, though, several battery startups are claiming price reductions that make energy storage on the grid look more feasible.
Fremont, CA-based Imergy Power Systems today said it’s developed a shipping container-size battery that will cost under $300 per kilowatt-hour, $200 less per kilowatt-hour than its last product. That price doesn’t mean that giant batteries will replace natural gas or coal power plants en masse, but it does make energy storage more attractive for specific uses, such as microgrids or providing power at peak hours of the day.
The CEO of Imergy is Bill Watkins, the former CEO of disk driver maker Seagate and LED lighting company Bridgelux. He joined the company last year after being convinced that the company’s flow battery technology could make a big dent in how the grid is run.
Its product uses two large tanks filled with vanadium electrolytes, each with a different state of charge. To release energy, the two fluids flow into a cell where a chemical reaction produces an electrical current. Flowing the liquids in the reverse direction through the cells when connected to the grid or another energy source recharges the battery.
Vanadium flow batteries have been around for many years, but the high cost of vanadium has made them relatively expensive. Imergey has developed a process to purify vanadium from the waste products of other industries, such as mining slag and fly ash. That allows it to recycle vanadium and lower its costs.
The company plans to start shipping its battery next month in the U.S. and India for microgrid applications. Like other modern battery systems, it has on-board computers and remote monitoring and management.
One of the compelling features of flow batteries is that they can store many hours of energy at a relatively low cost. Imergy’s battery can deliver 50 kilowatts of power—enough to power several buildings—for between two hours and 12 hours depending on how large the electrolyte tanks are.
Some of the companies claiming the lowest cost are making flow batteries. Sunnyvale, CA-based EnerVault earlier this year plugged in a full-size flow battery for a Department of Energy-funded project and said it expect to deliver commercial systems for around $250 per kilowatt-hour of capacity. By comparison, the lithium ion batteries used in electric vehicles and consumer electronics costs roughly twice that price.
Another company to watch is UniEnergies Technologies, based near Seattle, which is commercializing a vanadium-based flow battery developed at the Pacific Northwest National Laboratory. In the Boston area is Ambri, an MIT spin-off making a liquid metal battery, and Aquion in Pittsburgh is making a low-cost sodium-ion battery for the grid.
Price isn’t the only thing that matters when it comes to grid storage; batteries need to be reliable and safe as well. But steeply lower costs make batteries viable for a broad set of uses, such as buffering wind farms or storing solar energy at a company or university campus.
Battery storage on the grid is still relatively immature and is only starting to be adopted by utilities. But it’s the companies with novel technologies that have the best chance of opening up the market and, along the way, make the grid more reliable and efficient.
