Pump power storage facilities have been online for decades. They are often near nuclear facilities which can not easily throttle up and down: http://www.nypa.

Pump power storage facilities have been online for decades. They are often near nuclear facilities which can not easily throttle up and down: http://www.nypa.gov/facilities/blengil.htm http://www.nypa.gov/facilities/blengil.htm I think your analogy to a battery is correct for these pump storage operations while a container of batteries is, by analogy, closer to a capacitor: able to deliver high pulses of current quickly but only for a very short time.