Even as recently as two years ago, utility-scale lithium-ion batteries were considered cutting edge technology, and just a few forward-thinking utilities were experimenting with the concept. These days, though, it seems there are few utilities that are not building, or at least not considering, the technology.

In some cases, batteries are being linked with solar generation (called solar+battery). In other cases, the batteries are part of microgrids, which can include solar and other sources of generation. Microgrids appeal to utilities for remote-location generation/storage, reducing or even eliminating the need for transmission or distribution wired systems through rough, isolated terrain. And in still other cases, battery projects are being designed and built as a way to store surplus generation from traditional baseload generation (such as coal) and make it available later when customer demand increases.

Last week, for example, Duke Energy announced plans to spend $500 million on battery storage over the next 15 years, increasing its current storage capacity 20-fold. Current projects include a 9-megawatt (MW) battery project in Rock Hill, N.C., and a 4-MW battery project (part of a solar-powered microgrid) in Hot Springs, N.C.

Up north, New York Power Authority (NYPA), which to date has never been involved in battery storage, just announced plans for a 20 MW battery project in the northern part of the state, largely because current transmission constraints in the utility's service territory often prevent energy from being delivered downstate.

"Storing renewable energy, by using a battery to absorb excess generation for later delivery through projects like this one, is a viable solution to this transmission constraint," states the NYPA press release.

NYPA also believes the project will help to kick-start energy storage adoption throughout the state, supporting Gov. Cuomo's Energy Storage Roadmap, a plan designed to achieve massive energy storage targets in the state, including construction of 1,500 MW of energy storage by 2025.

"The North Country Energy Storage Project will be a first-of-its-kind for the Power Authority," said Gil Quiniones, president and CEO of NYPA. "Developing, operating and optimizing a lithium-ion battery system of this size will help us advance energy storage development efforts at the Power Authority, as well as position us to lead storage adoption across the state."

Out west, Hawaiian Electric Cos. (Hawaiian Electric, Maui Electric, and Hawaii Electric Light) just announced seven solar+storage projects on three islands, representing the largest infusion of renewable energy in the state's history. The seven solar projects, totaling 255 MW, will be connected to battery storage systems that will be able to capture up to four hours of electricity for later use.