The wind and the sun are inexhaustible sources of energy, and we are tapping into them to produce electricity at a growing rate around the world. But neither of them is always available when we need them. When the sun isn’t shining and the wind isn’t blowing, they don’t work.
An opposite problem also exists. When our energy needs are low, but it is sunny or windy, solar and wind power are all dressed up with nowhere to go. Energy storage is the answer to both of these problems. When there is excess generation, store the energy for later use. When there is need for energy and not enough is being generated, tap into the energy that is stored.
Giant banks of lithium-ion batteries are the rapidly growing form of energy storage, and they are increasingly providing resilience in the electric grid. But battery storage is short-term energy storage. Even the largest battery banks can only provide a few hours of electricity.
So, there is a real need for “long-duration energy storage” – systems that provide at least 10 hours of backup power and sometimes much more – for the grid to be fully reliable.
Pumped hydro storage, which uses water from elevated reservoirs to drive turbines, has been around for a long time. Historically, this is the largest form of energy storage in the world. Other methods include pumping compressed air into underground caverns or lifting massive blocks into elevated positions. All of these techniques use excess electricity to place things like water, air, or cement into a position where they can be used to drive electrical generators.
The grid of tomorrow will store energy in giant battery banks, but also in the ground, in reservoirs, and in large structures.
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How giant ‘batteries’ in the Earth could slash your electricity bills
Photo, posted March 21, 2024, courtesy of Sandra Uecker/USFWS via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio
