Number of energy storage projects in the U.S. 2011-2021, by technology

The number of electrochemical and pumped hydropower energy storage projects amounted to 646 in the United States in 2021. Over 90 percent of them used electrochemical technologies, which include batteries. While pumped hydroelectric energy storage showed a year-over-year increase of one project on average, electrochemical energy storage projects grew exponentially from only 25 in 2011 to 603 in 2021. Other energy storage projects in the U.S. in 2021 were thermal storage and electrochemical, accounting for almost 30 percent of the national energy storage projects.