A new study finds that aquifer thermal energy storage could dramatically reduce the electricity needed to cool AI data centers while recovering waste heat for nearby buildings.
Geothermal batteries for AI data centers
Over the past few years, artificial intelligence (AI) applications have evolved from a niche area of IT research into a multi-trillion-dollar commercial industry. That explosive growth is driving an equally rapid increase in the energy demand of AI data centers.
The largest share of electricity consumption is naturally tied to computing power. A single query submitted to a large language model such as Gemini or ChatGPT consumes about 3 Wh, roughly ten times more than a standard Google search.
However, server power is only part of the overall energy footprint. Storage systems, networking equipment, cooling and environmental control systems, uninterruptible power supplies, and building services such as lighting also contribute significantly to total electricity demand.
IEA (2025), Global data center electricity consumption by equipment, Base Case Scenario, 2020-2030, IEA, Paris. License: CC BY 4.0.
How much electricity do data centers consume?
The combined impact of these systems is already visible in global electricity demand. In 2024, all data centers, both AI and conventional, accounted for approximately 1.5% of worldwide electricity consumption, equal to 415 terawatt-hours (TWh). By 2030, driven largely by AI, consumption is projected to reach 945 TWh, just under 3% of global electricity demand.
Slowing this growth has become a strategic priority for the United States, China, and Europe, which together account for 85% of global data center electricity consumption.
One of the most immediate opportunities lies in improving cooling systems, which are responsible for between 10% and 39% of total electricity use, depending on computing intensity. This is where a new study by Yu-Feng Lin, Andrew Stumpf, and postdoctoral researcher Upasana Pandey from the Illinois State Geological Survey comes in. Their research examines aquifer thermal energy storage (ATES) as a technically viable solution for cooling data centers.
While the analysis focuses on the United States, which represented 45% of global data center electricity demand in 2024, its findings have broader international relevance.
Geothermal batteries
Aquifer Thermal Energy Storage (ATES) functions as a type of geothermal battery by using groundwater and its naturally stable temperature to store and recover seasonal thermal energy.
During summer, cool groundwater is pumped from a “cold well,” circulated through a heat exchanger to cool servers, and then reinjected, after absorbing heat, into a separate “warm well.” During winter, the process is reversed. The stored thermal energy can be recovered to heat nearby buildings or feed district heating networks. Once the heat has been extracted, the cooled water is returned to the cold well, ready for the next seasonal cycle.
Geothermal batteries are not a new technology. Europe has decades of experience deploying ATES systems. Today, the Netherlands dominates the sector with approximately 85% of all operational ATES installations worldwide, hosting more than 3,000 active systems. This leadership reflects both favorable hydrogeological conditions and a supportive regulatory framework. Sweden, Belgium, and Denmark together account for roughly another 10% of global installations.
Adapting these systems to AI data center cooling, however, requires additional technical considerations.
Low-temperature and high-temperature ATES
The study distinguishes between two categories of aquifer thermal storage based on storage temperature: low-temperature ATES (LT-ATES) and high-temperature ATES (HT-ATES).
As the authors explain, LT-ATES systems are generally “charged during the warm season by injecting waste heat into the aquifer at temperatures up to approximately 25°C and often operate in combination with a heat pump. In contrast, HT-ATES systems operate at significantly higher storage temperatures, typically above 40°C.”
This means LT-ATES geothermal batteries are well suited for air-cooled or hybrid air-liquid cooled data centers, where waste heat temperatures generally range from 15°C to 30°C. HT-ATES systems, meanwhile, are better matched to modern liquid-cooled data centers that generate waste heat between 50°C and 60°C.
Credits: “Aquifer Thermal Energy Storage: Groundwater for Efficient Data Center Cooling in the United States,” by Upasana Pandey, Andrew J. Stumpf, and Yu-Feng F. Lin, published in Groundwater. https://doi.org/10.1111/gwat.70084
How much energy can be saved?
Under an ideal scenario based on a mid-sized data center requiring 5 MW of continuous cooling, geothermal batteries with a coefficient of performance (COP) above 10 could reduce annual cooling electricity consumption from 14.6 GWh using conventional systems to just 4.4 GWh.
That represents an energy reduction of approximately 70%.
The researchers also examined regional suitability, highlighting Illinois as particularly favorable because of its pronounced seasonal temperature variations, abundant aquifers, and suitable groundwater chemistry.
Although the technology is mature and local geology is favorable, economic barriers remain significant. ATES systems require higher upfront investment, even though they deliver substantially lower operating costs over time. The main challenge is that many projects are evaluated using investment horizons of just 5 to 10 years, rather than the 20 to 40 years over which these systems provide their greatest economic benefits.
The findings also raise an interesting question for Italy. The country is emerging as one of Europe’s fastest-growing data center markets, with more than €25 billion in announced investments between 2026 and 2028. Milan, particularly the Settimo Milanese and Siziano clusters, together with Rome, are attracting the largest projects and capital commitments. From a hydrogeological perspective, however, the Po Valley may offer the strongest potential for geothermal batteries, thanks to its extensive layered aquifer systems.
The paper, Aquifer thermal energy storage: groundwater for efficient data center cooling in the United States, is available online.
