Grid scale energy systems, especially those with renewable energy inputs, need storage.
They need better and cleaner and more efficient storage solutions, and one company believes the answer lies in electric trains and gravity.
The most common way to store energy on a grid scale is through using “pumped” hydropower, where the off-peak energy is stored as water pumped to a higher elevation, which can then be released to produce electricity as gravity pulls it down to a lower elevation again.
Pumped hydro is effective, but it has a number of drawbacks, mostly in the difficulty of finding the right site for it, and the need for lots of water.
But what if the same principles could be used without water as the prime mover?
Advanced Rail Energy Storage, or ARES, is advocating for a unique energy storage technology that uses a dedicated fleet of electric shuttle-trains, operating on a closed rail network, to transport heavy masses between two different elevations, storing and releasing energy with the movements of the trains.
“During periods where excess energy is available on the grid, ARES shuttle-trains draw electricity from the grid, which powers their individual axle-drive motors, as they transport a continuous flow of masses uphill against the force of gravity to an upper storage yard. When the grid requires energy to meet periods of high demand, this process is reversed. The shuttle-trains provide a continuous flow of masses returning to the lower storage yard with their motors operating as generators, converting the potential energy of the masses elevation back into electricity in a highly efficient process.” – ARES
According to the company, which will soon to be testing a version of their system at a location in California, their system is capable of an 80% charge/discharge efficiency, and is scalable in size from 100 MW capacity up to 3 GW. The system, being based on electric motors and generators, releases no dangerous or toxic emissions, and requires no water to operate.
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