Pumped storage
Pumped storage hydropower is currently the leading energy storage technology in the U.S., accounting for more than 90 percent of the utility-scale storage rated power in the country. In 2021, pumped storage capacity in the U.S. stood at more than 21.9 gigawatts, the second largest in the world, only behind China. Pumped storage is an established technology that has been used for years to provide flexibility to the power grid. In fact, roughly seven out of ten utility-scale facilities in operation in the U.S. started operation in the 1960s and 1970s. As of 2020, California, Virginia, and South Carolina were the leading U.S. states in hydropower storage capacity, each with more than 2.5 gigawatts.Batteries
While pumped hydropower is the historic choice of energy storage used in the U.S., batteries are the current trend. Battery capacity additions in the U.S. surpassed three gigawatts in 2021, a record high. This record is expected to be quickly broken, with another 5.8 gigawatts worth of additions projected for 2022. Meanwhile, around 200 gigawatts worth of standalone battery projects were in interconnection queues in the U.S., with another 200 gigawatts also awaiting connection as part of hybrid projects, mainly in combination with wind and solar power generation.In 2020, lithium-ion was the main composition of large-scale battery storage installations in the U.S., accounting for roughly 94 percent of the installed capacity. In terms of regional distribution, California led the ranking that year. The Golden State had over 535 megawatts in operation at the time, more than double the operational capacity of runner-up Texas. The Californian market has benefitted from a state-level policy, which mandated the procurement of more than one gigawatt of energy storage capacity by their investor-owned utilities by 2020.
