The story of US energy storage

Energy storage has been a hot topic and growth sector in the sustainable energy space for years. Utilities, regulators, and customers see value in various types of energy storage, such as electrochemical storage in batteries, thermal storage in ice or water, and mechanical storage designs. Consumers, utilities, and policymakers also consider storage “duration,” or how long an energy storage system can continuously output its rated power. As of February, 12 US states have energy storage targets, the largest of which is in New York, which has a goal of 6 GW by 2030.

In mid-2024, lawmakers in Rhode Island established a 600 MW energy storage goal, to be achieved by 2033. In Massachusetts, the governor signed a bill establishing new energy storage requirements in late 2024. That bill, S.B. 2967, adds language to statutes requiring that all utilities jointly solicit proposals for up to 5 GW of energy storage projects. The statute would require storage projects of varying duration to be contracted by July 31, 2030, consisting of 3.5 GW of mid-duration energy storage, 750 MW of long-duration storage, and 750 MW of multi-day energy storage. In the law, Massachusetts defined short-duration storage as two to four hours of continuous output. Mid-duration is four to 10 hours, long-duration is 10 to 24 hours, and multi-day storage must be capable of dispatching a system’s full rated output for longer than 24 hours.

State energy storage targets (February 2025)

Several state legislatures have proposed actions to create new, or amend existing energy storage targets in the last year. A bill codifying the New Jersey Energy Master Plan is pending in the State Senate. That bill would set a goal of 2 GW of energy storage projects, capable of discharging for at least 24 hours, to be active in the state by 2035. Lawmakers in Illinois introduced several bills in mid-2024 which included energy storage procurement targets. One pair of bills targets 7.5 GW by 2030 and a separate set would set the goal at 9 GW by 2030 and 15 GW by 2038. Legislators in New York introduced bills to double the state’s storage targets, from 3 GW to 6 GW but those bills did not advance during the legislative session. The New York Public Service Commission, however, issued an order adopting an energy storage roadmap for the state and setting the 6 GW goal.

Utilities frequently propose new storage deployment, even in states and regions where legislative mandates are not in place, noting the services that energy storage can provide, such as load or frequency balancing or providing peaking capacity. Idaho Power and Public Service Company of New Mexico factor dispatchable balancing assets, including energy storage, into their capacity procurement plans. As coal plants and other large generators become uneconomical and retire, balancing services from energy storage will become more important to maintain the reliability of the electric grid.

As of February 2025, utilities had active or pending procurement exercises for energy storage assets operating in states without energy storage mandates. If all of the RfPs, applications, and other utility proposals that were active at the end of 2024 materialize, utilities will add more than 18.5 GW of energy storage capacity in places including Arkansas, Louisiana, Georgia, Iowa, Indiana, Puerto Rico, Texas, Washington, and Wisconsin. Interestingly, there seems to be robust participation in many storage solicitations, irrespective of geography. According to a statement from utility Puget Sound Energy, its recent RfPs sought 29 MW of storage but received proposals for a total of 229 MW.

Noteworthy recent energy storage procurement

Recently, several proposals have sought to use thermal energy storage to offset peak grid demand. Utilities in Georgia, Kentucky, Indiana, Iowa, and Wisconsin have either opened RfPs or petitioned for regulatory approval of energy storage, which includes thermal energy as well as electrical. Thermal storage can offset energy use for heating or cooling by directly storing the energy type that will be needed. For example, chilled water storage can run electric water chillers overnight, when power is less expensive, and distribute the chilled water for cooling during a hot afternoon, to avoid more expensive power purchases.

Vincent Potter is a project manager at North Carolina Clean Energy Technology Center.

This article was originally published by NC Clean Energy Technology Center. Click here to learn about its DSIRE Insight subscriptions, custom research, and consulting offering for clean energy technology for interested individuals or organizations.