Solar and wind energy systems require some means of saving power for times when the sun doesn’t shine and the wind doesn’t blow. Such approaches, from batteries to gravity, are developing rapidly and in many different directions.
The pieces below sample the richness and complexity of this important topic.
Batteries
It can feel impossible, at least for a nonspecialist, to stay current on research into new kinds of “regular” batteries, never mind those suitable for large-scale energy storage. One fairly promising recent development is the iron-air battery – or, we might say, rust. See “How iron-air batteries could fill gaps in renewable energy” (Alissa Greenberg, NOVA) for an engaging and thorough introduction.
For a good overview of the energy storage situation at the end of last year, focused on batteries collected to act at grid scales, read “2024 was a fantastic year for energy storage” (Julian Spector, Canary Media). Another encouraging overview is this one by Oliver Milman in the Guardian: “U.S. power grid added battery equivalent of 20 nuclear reactors in past four years.”
Hydrogen
Hydrogen gas can be produced with excess clean energy (“green hydrogen”) and stored until it is needed; then, mixed with methane, it is burned to create more energy, creating less pollution than methane (or “natural gas”) alone. For a pair of stories about one such project, see “A huge underground battery is coming to a tiny Utah town” (Henry Fountain, New York Times) and “Hydrogen is transforming a tiny Utah coal town. Could its success hold lessons for similar communities?” (Emma Penrod, Utility Dive).
Gravity: water
“Pumped hydro” storage requires two water reservoirs at different elevations. When power is abundant, water is pumped uphill; when it is needed, it flows downhill through turbines, creating usable electricity. For the surprisingly large number of large-scale facilities of this type, many of them in China, see this Wikipedia article: “List of pumped-storage hydroelectric power stations.” And for an underground version, see “Revolutionary new Swiss ‘water battery’ will be one of Europe’s main renewable sources of energy” (Rebecca Ann Hughes, Euronews).
Gravity: other weights
Of course, it’s not only water that can be moved upward and released downward; weights are easy to find, and other kinds of vertical distances are starting to interest battery innovators. Elevators in very tall buildings, for instance: “Researchers propose turning high-rises into gravity batteries” (Prachi Patel, Anthropocene). Old mine shafts: “Abandoned coal mines are becoming the batteries of the future” (Natasha Khullar Relph, Reasons to Be Cheerful). Even simple train tracks up hillsides: “The train goes up, the train goes down: a simple new way to store energy” (David Roberts, Vox). (It’s not clear whether this project still exists, though the company seems to.)
Thermal
Several types of thermal energy storage are being explored. One is “sensible heat storage” – simply heating and cooling some kind of material. For instance, sand batteries in Finland: “How a sand battery could transform clean energy” (Erika Benke, BBC) and “A tiny town is betting on a sand battery to heat homes. It could revolutionize energy” (Tim Newcomb, Popular Mechanics).
Another involves pumping water deep underground to make use of fracking technology, geothermal heat, and water pressure, as in “This Texas geothermal startup is storing energy in the ground” (Maria Gallucci, Canary Media). As is usual in Canary Media stories, this one is quite thorough, a little bit technical, and mentions other related experiments.
For more
To learn about other types of energy storage – and the varied ways they are categorized – see “The different types of energy storage and their opportunities,” Jonathan Spencer Jones, Smart Energy International, or “An overview on classification of energy storage systems,” Mohanraj Kandhasamy et.al., ACS Publications (American Chemical Society).
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