New York Gov. Andrew Cuomo this month announced an ambitious plan for deploying energy storage, a technology that can mitigate renewable power’s most persistent problem: how to use it when the sun isn't shining or the wind isn't blowing.

“This is the clearest and most ambitious policy signal the energy storage market has seen on the East Coast,” said Jason Burwen, policy and advocacy director of the Energy Storage Association, a trade group for the industry.

Cuomo, a Democrat, announced his energy storage goals Jan. 2 as part of a "comprehensive agenda to combat climate change" that also calls for increased development of offshore wind, new energy-efficiency targets, and a reiteration of his pledge for the state to obtain half of its power from renewable energy by 2030.

To reach the renewable power target, Cuomo wants to deploy 1,500 megawatts of energy storage by 2025.

That's a bigger target than California's first-in-the-nation 1,300-megawatt mandate, although New York’s deadline is five years later, when storage technology is expected to be cheaper.

About 800 megawatts of battery energy storage is deployed across the U.S. currently, according to Burwen.

Most importantly to advocates, Cuomo is putting money behind his energy storage goal. He committed $200 million from the NY Green Bank, which supports clean energy projects through funding mostly provided by private capital from banks.

The New York State Energy Research and Development Authority will invest an additional $60 million in pilot storage projects.

Before now, Cuomo mostly downplayed energy storage as part of New York's four-year effort to overhaul its power grid.

The New York legislature unanimously passed legislation last year to create an energy storage deployment program. Cuomo was slow to endorse the bill, finally signing it on Nov. 29, more than five months later. The law calls on the New York Public Service Commission to set an energy storage deployment target for 2030.

The governor’s energy czar, Richard Kauffman, had expressed doubt about whether such a mandate was a good fit with the market-driven approach Cuomo has favored to move the state toward using more renewables. But Cuomo aimed to alleviate that concern by promising a funding stream to meet the energy storage targets and advocating a competitive process to win the money.

“New York has focused on meeting state energy policy goals through market mechanisms when possible, and the use of Green Bank funds is intended to kick-start private financing of storage,” Burwen said.

Energy storage is becoming cheaper and more diverse, from various kinds of batteries and pumped hydro to thermal storage. It is not a power source. Rather, a battery or other storage resource carries excess energy that is produced when demand for electricity isn't peaking.

“Because renewables are intermittent, you could use storage to store that clean electricity when it’s produced, and use it when it's most needed,” said Anne Reynolds, executive director of the Alliance for Clean Energy New York. “That will allow the grid to deploy more renewable energy more quickly.”

The state generates about 25 percent of its power from renewables, halfway to its 50 percent goal by 2030. Most of the state’s renewable energy is hydropower, with 3 percent coming from wind and solar.

Reynolds said most of New York’s renewable power is generated upstate, and old transmission lines limit how efficiently that energy can be transported downstate.

“If we can invest in storage, that will mitigate the need for some of that quite old transmission,” Reynolds said.

While Cuomo’s vision for energy storage was met with broad support from renewable advocates, some want the governor to assure the investments won’t increase costs for power customers.

Gavin Donohue, president and CEO of Independent Power Producers of New York, a trade association representing the power industry, said he represents companies interested in pursuing energy storage projects.

Donohue said the state’s progress on implementing Cuomo’s renewable energy goals has been “painfully slow,” and he wants to see more specifics about how the governor will achieve them.

“This governor likes to think big and put out big ideas,” Donohue said. “But how to do energy storage in a way that makes sense for ratepayers, and promotes resilience and reliability, is an open question at this point.”