Aquifers: The Surprise Player in Long-Term Energy Storage

USGS modelling and early projects revive interest in underground thermal storage for seasonal energy needs

6 May 2025

Researchers at the U.S. Geological Survey are giving new attention to aquifer thermal energy storage, or ATES, a technology designed to solve a stubborn problem in renewable power: how to store energy not for hours, but for seasons.

Batteries excel at smoothing daily peaks. They struggle when summer’s excess needs to be saved for winter. Aquifers, the vast underground layers of water-bearing rock, offer a different answer. Heat can be stored underground for months, then retrieved when demand rises.

USGS has sharpened its SUTRA modeling software to better simulate how heat and fluids move through subsurface formations. The work builds on findings detailed in a 2025 paper by Pepin and colleagues in Geothermics. While long-term simulation results have not been fully released, the updated framework gives researchers and developers a clearer view of how heat behaves underground over decades.

That clarity is already influencing real projects. Companies such as Schneider Electric are deploying ATES in high-performance buildings, including the landmark Edge complex in Amsterdam. These systems are not lab experiments. They are operating assets, helping cool buildings in summer and warm them in winter by cycling heat through underground reservoirs.

Institutional interest is growing alongside industry uptake. The Electric Power Research Institute is studying how large-scale thermal storage could support future grids, especially as wind and solar expand. The Department of Energy is also watching closely, weighing how underground heat storage fits into broader decarbonization plans.

Regulators, meanwhile, are starting to ask careful questions. Aquifer chemistry, geology, and water protections vary widely by region. Permitting and monitoring will matter as systems scale.

Still, momentum is building. With better data, proven pilots, and supportive policy, aquifer thermal storage is moving from a niche idea to a practical tool.

In the race to decarbonize, the ability to bank summer heat for winter demand may soon feel less like a novelty and more like common sense.