When you coil a spring, you load it with a bunch of potential energy that gets released when you let go. Using the same basic principle, a Scottish company called Gravitricity is creating an energy storage facility that uses weights instead of springs to store energy.
The idea is to hold 500 to 5,000-ton weights aloft using powerful cables and winches. Then, when energy is needed, these weights can be lowered down to a mineshaft to spin the winch and feed electricity into the grid. The new facility is meant to be a prototype unit of gravity-based energy storage.
Gravitricity believes these units could have peak power outputs of between 1 and 20 MW and could function up to 50 years with no loss of performance. Plus, because the system can go from zero to full power in under a second, it can quickly release its power payload in as little as 15 minutes or slow it down to last up to eight hours.
When the giant mechanical battery needs to be recharged, electricity from renewable sources can power the winches to lift the weights back to the top. In the end, the demonstration facility will feature a tower that stands at 52.5 ft tall and is expected to be ready for testing Spring 2021.