Gravity is a powerful, inescapable force that surrounds us at all times – and it also underpins one of the most established energy storage technologies, pumped hydro-power. Currently the most common type of energy storage is pumped hyroelectric facilities, and we have employed this utility-scale gravity storage technology for the better part of the last century in the United States and around the world.
A hydroelectric dam relies on water cascading down through a turbine to create electricity to be used on the grid. In order to store energy for use at a later time, there are a number of different projects that use pumps to elevate water into a retained pool behind a dam – creating an on-demand energy source that can be unleashed rapidly. When more energy is needed on the grid, that pool is opened up to run through turbines and produce electricity.
But the material that is raised to a higher elevation doesn’t have to be water. Companies are currently creating gravitational systems that move gravel up the side of a hill and use the same underpinning principle – when energy is needed, the gravel is released and the weight drives a mechanical system that drives a turbine and generates electricity.
Because of the immense scale achieved through these applications, this is the most common type of grid-level energy storage based on megawatts installed today.