Then, when the wind drops, the sun stops shining, or electricity demand rises, the rail cars are released back down the hill, generating electricity through regenerative braking.

Because the system doesn’t rely on the use of water like the aforementioned ocean-based systems, the company says the technology is suitable for a wider variety of areas with minimal environmental impact. The company says the system can also respond to increases or decreases in demand in a matter of seconds, boasts a charge/discharge efficiency of 86 percent, and can deliver constant power for periods of up to eight hours.

ARES’ Director of Technology Development, William Peitzke told us to think of the system as basically a “grid-scale flywheel or battery, but one which is able to lock into direct synchronization with the grid providing heavy inertia for added grid stability.”