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Study Shows Dual-Mode “Thermal Battery” Cuts Peak Heating and Cooling Demand

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CEEE graduate research assistant Al-Hussain Othman and colleagues demonstrated that an innovative heat pump–thermal storage design could help prevent electrical grid overload across the United States by reducing peak-hour cooling and heating demands.

As the demand for electrical power networks continues to mount, the University of Maryland Center for Environmental Energy Engineering is advancing methods to help prevent grid overload and related power outages. One promising solution: heat pumps integrated with thermal energy storage (HP-TES), which allow the system to store energy during off-peak hours and use it during peak-demand hours, reducing stress on the grid.

In a recent publication in Energy and Buildings, a CEEE research team presented an innovative HP-TES design and demonstrated that it could reduce annual peak-hour heating demand by 40–65% and cooling demand by 15–20%. By decreasing electricity use during peak-demand hours — when energy prices are typically highest — the technology could also cut consumer costs.

The CEEE team designed a dual-mode HP-TES for both heating and cooling. Most dual-mode designs require two separate tanks — one for cooling (e.g., using cold water or ice) and another for heating (e.g., using hot water). In contrast, this design uses a single thermal battery with a phase change material (PCM), a substance that stores heat as it melts and releases heat as it solidifies. For this study, the team chose a salt-hydrate PCM that melts/solidifies around room temperature, making it an energy-efficient, cost-effective candidate in both heating and cooling modes.

“This design greatly reduces the cost of having two systems,” says lead author Al-Hussain Othman, a CEEE graduate research assistant and a doctoral candidate in the Department of Mechanical Engineering.  “It’s also significantly less expensive to recharge a system that uses a room temperature PCM, compared to recharging ice or reheating water. It’s a much smaller temperature lift.”

“A technology like this could reduce environmental impact and also help end users lower their utility bills every month.”

CEEE researcher Al-Hussain Othman

While other researchers have proposed similar concepts, this study moves the technology closer to deployment by presenting a detailed, practical design that accounts for real-world constraints, such as PCM properties and space limitations. The publication’s co-authors are CEEE Director and Research Professor Vikrant Aute and postdoctoral researcher James Tancabel.

This study is believed to be the first to provide a comprehensive performance assessment across different climate zones. The researchers simulated a full year of system performance across eight U.S. climate zones using typical weather data. The novel system significantly lowered peak-period demand in both modes, with heating savings more than double those for cooling, largely due to reduced need for backup heating in cold climates. 

“When you are shifting peak loads, you need to make sure you're not just moving the problem from one part of the day to another,” says Othman. The CEEE study introduces a metric called the recharge energy increase to help evaluate whether shifting demand also unintentionally creates new periods of high electricity use. 

“Big picture, we want to reduce carbon emissions,” Othman says. “A technology like this could reduce environmental impact and also help end users lower their utility bills every month.”  

Download the paper: “Design and performance assessment of a dual-mode latent thermal storage integrated heat pump across multiple climate zones.”

Published June 3, 2026