As artificial intelligence and digital infrastructure expand rapidly, data centers across the globe generate immense amounts of heat every second. This excess heat poses a significant challenge to power grids and environmental sustainability. By repurposing this waste thermal energy, Lehigh University's thermal battery technology offers a cost-effective solution to recover and upgrade waste heat into usable energy, improving power system stability and reducing operational costs for critical infrastructure.
The Background/Motivation
Data centers produce massive volumes of excess heat from servers and electronic equipment. Keeping these facilities cool is essential to prevent hardware damage and ensure reliable performance, but traditional cooling systems consume substantial electrical power. Furthermore, the heat removed from data centers is discarded directly into the environment. Capturing and upgrading this waste heat presents an opportunity to improve overall energy efficiency and lower carbon footprints.
The Innovation/Methodology
Lehigh researchers have developed a Thermosiphon-embedded Cementitious Matrix for sensible Thermal Energy Storage (TCM-TES), functioning as a thermal battery. The technology combines an engineered cementitious matrix with embedded finned thermosiphons designed for modular operation at temperatures suited for heat recovery from data centers.
During operation, the thermosiphons transfer heat into or out of the storage media under isothermal conditions rapidly and efficiently. The system can work on heat-to-heat as well as electricity-to-heat modes, allowing waste heat and low-cost electricity (when available) from data centers to be captured, stored and upgraded for practical applications, such as district heating, drying processes and industrial processes.
Results/Impact
The thermal battery design demonstrates strong performance metrics for scalable energy deployment:
- High Efficiency: Achieves a round-trip efficiency greater than 70%.
- Versatile Applications: Capable of heat upgrading between 120°C and 220°C for data centers, generating power via low-temperature Organic Rankine Cycles ranging from kilowatt to megawatt scale, and powering absorption refrigeration chillers for direct data center cooling. The thermal battery is also capable of operating at higher temperatures of up to 500°C for applications in flexibilization of power generation assets, decarbonization and concentrated solar power (CSP).
- Demonstrated Scale: Fabrication and assembly were validated on a 150 kWh thermal battery prototype setup.
Conclusion/Outlook
Lehigh's hybrid, sensible-latent heat thermal energy storage system offers a pathway to integrate thermal storage into data center operations and power generation infrastructure. The technology is under licensing from Lehigh University to Energy Storage Technologies, Inc. Future developments will focus on expanding the integration of these thermal batteries into existing energy networks to enhance grid flexibility and optimize industrial waste heat recovery.
This material is based upon work funded by the U.S. Department of Energy Award Number DE-FE0031755. Reference works include publication analyses from IRENA (2019) and Bravo et al., "Design and experimental testing of a 150 kWh thermal battery using thermosiphons embedded in a concrete matrix for power plant flexible operation," Energy, 277 (2023).
Generative AI was used to organize this story, based on data and information presented in a research poster. It was reviewed and edited by faculty and communications staff.
This research was presented as part of the Innovating Energy and Water Solutions for Tomorrow's AI Data Centers Symposium hosted by the Center for Advancing Community Electrification Solutions (ACES) in October 2025
