A company called Energy Vault has proposed a new utility-scale battery that is both old and new at the same time. The “battery” is mechanical, rather than chemical, and stores energy much like pumped hydro does, but it does it with bricks.
If you’re not familiar with pumped hydro, it works like this. The system pumps water from a lower elevation to a higher elevation when electricity is plentiful and cheap. When electricity becomes more expensive, operators release that water through a hydroelectric turbine to give the grid some extra juice. Similarly, Energy Vault wants to build a system of six cranes, which will electrically stack heavy bricks into a tower when electricity is cheap and plentiful. When electricity becomes more scarce and expensive, the cranes will release each brick and harvest the energy from their fall.
This system solves an important problem inherent to pumped hydro: it requires a pretty specific kind of topography and often causes environmental concerns.