Using potential energy to store electricity is nothing new. Many hydroelectric damns pump water to a high reservoir when there is excess electricity generated

Using potential energy to store electricity is nothing new. Many hydroelectric damns pump water to a high reservoir when there is excess electricity generated to store it, and let it fall to a low reservoir when more is needed. EDIT: See wikipedia link explaining it, with examples. http://en.wikipedia.org/wiki/Hydroelectric_energy_storage http://en.wikipedia.org/wiki/Hydroelectric_energy_storage