The United States Department of Energy's Global Energy Storage Database (GESDB) is a free-access database of energy storage projects and policies funded by the U.S. DOE, Office of Electricity, and Sandia National Labs.
[1] In 2013, the database covered 409 projects; it aimed to cover all energy storage projects globally by 2014.
[2] By 2020, it covered 1,686 projects,[3] comprising 22 gigawatt power of US grid storage capacity.
Pumped-storage hydroelectricity is around 90% of the energy capacity.
Storage facilities are 80% efficient.