Utility-scale battery storage systems are increasingly being installed in the United States, the Energy Information Administration reported on Aug. 10.
In 2010 the U.S. had seven operational battery storage systems, accounting for 59 megawatts of power capacity and 21 megawatt-hours of energy capacity. By the end of 2018, the U.S. had 125 operational battery storage systems, providing a total of 869 MW of installed power capacity and 1,236 MWh of energy capacity, EIA noted.
Battery storage systems store electricity produced by generators or pulled directly from the electrical grid, and redistribute the power later as needed. These systems have a variety of applications, including integrating renewables into the grid, peak shaving, frequency regulation, and providing backup power.
Most utility-scale battery storage capacity is installed in regions covered by independent system operators (ISOs) or regional transmission organizations (RTOs).
Historically, battery systems have been in the PJM Interconnection and the California Independent System Operator (CAISO).
CAISO and PJM combined accounted for 55% of the total battery storage power capacity built between 2010 and 2018. However, in 2018, more than 58% (130 MW) of new storage power capacity additions, representing 69% (337 MWh) of energy capacity additions, were installed in states outside of those areas.
In 2018, several regions outside of CAISO and PJM began increasing the amount of battery storage capacity to their power grids, including Alaska and Hawaii, the Electric Reliability Council of Texas (ERCOT), and the Midcontinent Independent System Operator (MISO). Many of the additions were the result of procurement requirements, financial incentives, and long-term planning mechanisms that promote the use of energy storage in the respective states. Alaska and Hawaii, which have isolated power grids, are expanding battery storage capacity to increase grid reliability and reduce dependence on expensive fossil fuel imports.
Average costs per unit of energy capacity decreased 61% between 2015 and 2017, dropping from $2,153 per kilowatt-hour (kWh) to $834 per kWh. The large decrease in cost makes battery storage more economical, helping accelerate capacity growth. Affordable battery storage also plays an important role in the continued integration of storage with intermittent renewable electricity sources such as wind and solar.