Long-term, utility-scale storage would turn solar and wind energy into on-demand sources of electricity
There’s the battery in your watch. There’s the battery in your mobile phone. And then there’s the battery at Green Mountain Power’s Stafford Hills solar farm in Rutland, Vt.
The lithium-ion gargantuan is housed in two trailer-truck-size green metal containers. It sits atop a 10-acre former landfill and captures electricity from 7,722 nearby solar panels—enough to power 2,000 homes on a sunny day. What’s revolutionary about this system isn’t the solar farm; it’s the size and purpose of the battery, which offers 3.4 megawatt-hours of storage, enough to supply backup power to about 170 homes for a day, if needed.
The rap on solar and wind is intermittence—they don’t produce power when the sun isn’t shining or the wind isn’t blowing, making them unreliable as the primary source for power grids. But if vast amounts of renewable energy—say, enough to power entire cities—could be captured and stored in giant batteries and deployed when needed, that downside would fade away.
This has been the “missing piece” in the renewable-energy revolution, says Venkat Srinivasan, director of the Energy Department’s Argonne Collaborative Center for Energy Storage Science. But it’s starting to come into view, thanks to the scale and progress of current research and real-world applications such as Green Mountain Power’s.
Green Mountain’s project puts it in the vanguard of power companies that are showing that utility-scale battery storage can be technologically and economically viable—depending on the scale and how it is used. Like all utilities, Green Mountain faces issues meeting “peak demand,” the high-use period, typically in the early evening, when people return from work and school and crank up air conditioners and energy-hungry appliances.
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