Dive Brief:

• Platts, reporting on storage data filed with FERC, concludes the United States had 565.5 MW of storage capacity installed at the end of the second quarter — with about a third of the capacity coming online in the last year.
• In total there are 45 grid-connected systems, the bulk of which are battery storage. Two projects are flywheel storage.
• Utilities are adding battery storage projects for reliability, ancillary services and the integration of more renewables. For instance, Arizona Public Service and AES Energy Storage just announced a plan this week to deploy 2 MW, 8 MWh batteries in a community northeast of Phoenix.

Dive Insight:

With new energy storage projects seeming to come online every week, 2016 was likely the "turning point" for grid-connected batteries in the United States. Utility-scale battery storage installed capacity grew by 221 MW in 2016, aided by the falling price of battery cells. And longer-duration batteries are taking hold as well.

Platts' report shows all of the nation's grid-connected storage is in 12 states, and about 277 MW is focused on frequency regulation. However, more utilities are using storage as a way to defer costly infrastructure upgrades and skirt natural gas construction.

APS' recent announcement is focused on deferring investment on a 20-mile transmission line. The battery will provide local generation during 20 to 30 peak power demand days per year, and on other days it will provide grid services to APS. The utility's 15-year integrated resource plan calls for the addition of 500 MW of energy storage.

Southern California Edison, for instance, is another utility using storage as a way to avoid natural gas construction and cut emissions. SCE's President Ron Nichols told Utility Dive the utility is also looking to pair energy storage with natural gas peakers to help cut emissions to meet California's carbon goals.

"We will constantly be looking at, every time we need a new resource — how can we avoid the need to add another gas-powered resource?” Nichols told Utility Dive in an interview at the Energy Storage North America conference this week. “Even if they are built, they're not gonna run much. They're going to be there exclusively for reliability, full stop. That would be the only reason they're added.”