Heat battery breakthrough shrinks storage space while storing heat

Researchers from the Norwegian organization SINTEF and Swiss company COWA Thermal Solutions have developed a novel thermal battery system that transforms home heat pumps into efficient heat storage units. This innovation allows heat pumps to store thermal energy when electricity rates are low and release heat during peak demand periods, addressing the challenge of variable renewable energy availability. The system uses salt hydrates—phase change materials that absorb and release heat through a solid-liquid phase transition—to store significantly more heat than water while occupying up to four times less space than traditional hot water tanks. Salt hydrates are safe, non-toxic, non-flammable, and cost-effective, making them suitable for residential applications. A key advancement in this technology is the use of cooling fins made from recycled aluminum to evenly distribute heat within the salt hydrates. Aluminum’s light weight, excellent thermal conductivity, and ease of forming make it ideal for this purpose, while recycling reduces environmental impact and cost. To prevent corrosion caused by impurities in recycled aluminum interacting with salt hydrates,