Tanya Weaver Tue 13 Jan 2026
Collected at: https://eandt.theiet.org/2026/01/13/thermal-battery-solution-turns-heat-pumps-home-energy-storage-systems-new-study
Home heat pumps can turn into compact energy storage units through a new system developed by Norwegian and Swiss researchers.
Researchers at Norwegian research organisation SINTEF and Swiss company COWA Thermal Solutions have developed a compact thermal battery that allows home heat pumps to store excess heat and release it when needed.
Galina Simonsen, a senior research scientist at SINTEF, said: “A heat pump that runs constantly is expensive, energy-consuming and can lead to overloading the power grid. With the new batteries, heat pumps combine storage and smart distribution of heat.”
Heat pumps extract energy from the environment – air, soil or water – and transport the heat into the home. However, heat demand in households vary depending on usage patterns, time of day, outdoor temperature and weather conditions.
To meet these fluctuations, the researchers developed a thermal energy storage solution that features salt hydrates. These materials lock water into their structure and can turn from solid to liquid when heated.
Simonsen said: “Think of thermal batteries as sponges: when they’re heated to a certain temperature, they undergo a change from solid to liquid and can store heat. When they are cooled, they return to solid form and release heat again.
“Salt hydrates aren’t toxic, they’re not flammable and they are also relatively inexpensive. This makes them a safe and good choice for use in private homes. Heat storage with salt hydrates also takes up less space than a traditional hot water tank, often up to four times less.”
To improve the solution’s storage capacity, the research team designed a heat sink. This features cooling fins made of recycled aluminium. With good thermal conductivity, this material distributes heat quickly and evenly through the salt hydrate.
To solve the issue of possible corrosion from the salt hydrates, the researchers coated the aluminium cooling fins with plasma electrolytic oxidation.
Simonsen said: “This coating is similar to what is used on non-stick pans and provides a very durable and corrosion-resistant barrier.”
According to the researchers, the new system delivers a major performance boost over traditional thermal storage solutions. Tests showed that the new design increases battery efficiency from 65% to 85%, while charging times have been cut by more than 70%. The time required to release stored heat has also been reduced by over 80%.
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