By Editors of Power Engineering

Energy storage continues to grow rapidly in the United States, and has reached a total of 565.5 MW for the first half of 2017.

Of that total, 181.5 MW was added over the last year, a study from Platts indicated.

Now, 22 companies own and operate 45 grid-connected energy storage units in 12 states. Nearly all the energy storage systems are battery storage other than two flywheel units.

PJM Interconnection is the home of over half of all energy storage at 23 units, and have a combined power rating of 301 MW. California Independent System Operator has 10 units totaling 114.2 MW. The largest of those is San Diego Gas & Electric’s 30-MW Escondido facility, which came online earlier this year.

The top energy storage companies by installed capacity are AES at 83.3 MW and NextEra Energy Resources at 76.4 MW. Invenergy Investment and Southern California Edison.