Photographer: Scott Barbour/Getty Images for the World Solar

Big Batteries, the Elusive Key to Clean Energy, Boomed in 2015

  • Energy Storage Association says capacity more than tripled
  • Industry added 221 megawatts of capacity, mostly by utilities

Large-scale energy-storage systems, long considered the elusive link to integrating solar and wind power into electric grids, are slowly becoming a reality.

U.S. homes and businesses -- mainly utilities -- installed storage systems with 221 megawatts of capacity in 2015, according to a study released Thursday by Boston-based GTM Research and the Energy Storage Association. That’s about enough to power a city the size of Cincinnati, Ohio, for an hour and is more than triple the 2014 total.

The U.S. has about 580 megawatts of energy storage installed now, up from 80 megawatts in 2008. The increase comes as power companies struggle to incorporate energy from wind and solar farms, where production ebbs and flows based on breezes and sunshine.

Renewable energy isn’t the only driver. Advocates for storage say the technology lets utilities run power plants more efficiently and makes once-fragile grids more resilient in the face of storms, blackouts and terror attacks.

“We can look back at 2015 as the year when energy storage really took off,” Ravi Manghani, a senior energy storage analyst for GTM, said in a statement.

Utility Storage

Utilities are the largest users of storage technology, accounting for 187 megawatts, or 85 percent, of systems installed in 2015. Most were in the markets served by the electric grid run by PJM Interconnection LLC. Utilities’ customers accounted for 35 megawatts.

Almost all of the systems installed used lithium ion batteries, said Matt Roberts, executive director of the Energy Storage Association, which expects the U.S. to have 4,000 megawatts of storage capacity by 2020. The study didn’t include pumped-storage hydroelectricity systems, which pump water up to hilltop reservoirs where it can be released to run through turbines to produce electricity.

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