Until recently, only two governmental bodies in the United States had set targets for energy storage: California and Massachusetts. Recently, though, New York City became the third governmental body to do so.

On Sept. 23, the city unveiled an energy storage goal of 100 megawatt-hours by 2020, along with an expanded solar target of 1,000 megawatts by 2030.

"The city's first-ever storage deployment target will help reduce reliance on the grid by making variable sources of energy production, such as solar panels, usable for more of the day," said Mayor Bill de Blasio. "Energy storage also helps increase the city's resiliency by providing backup energy when the grid is offline."

An additional benefit of both initiatives is the ability to help the city meet its goal (set in 2014) of reducing greenhouse gases by 80 percent by 2050.

The Energy Storage Association hailed the decision as a big step for the industry that will serve as a model for other major cities.

"Today, we are excited to announce that solar power capacity has nearly quadrupled since 2013, driven by the city's regulatory reform and smart investments," said Daniel Zarelli, the city's senior director for Climate Policy and Programs and the city's chief resilience officer. "And we are pleased to build on this success now by expanding our commitment to powering the city with solar energy and recognizing the role that energy storage will play in our future and supporting the growth of this critical technology with additional reforms."

"Good environmental policy is good economics," said Maria Torres-Springer, president of the New York City Economic Development Corp. "By quadrupling installed solar in the city and adopting ambitious solar and storage targets, we continue to support New York's growing climate industry, while decreasing the cost of solar for communities and working toward a more sustainable future."

"With these ambitious solar and energy storage targets, DCAS [the Department of Citywide Administrative Services] will continue to lead by example and expand our solar PV and battery installations at schools, hospitals, offices and other municipal facilities throughout the five boroughs," said Lisette Camilo, commissioner of the DCAS.

By the city's definition, energy storage can include both electrochemical (battery) and thermal storage. However, because of growing concerns over the safety of the most popular large-scale storage batteries—lithium-ion (which can pose a fire risk)—the New York City Fire Department and the city's Department of Buildings continue to research these safety concerns, and the city wants to learn more about this issue before implementing lithium-ion batteries on a large scale, especially in dense urban areas.