Heatstock – inventing a novel heat storage material

Novel heat storage material was invented at Aalto that is able to bring the summer’s heat into the winter time.

Project Leader: Ari Seppälä | Visit website

The Applied Thermodynamics group led by Ari Seppälä has invented a novel heat storage material during the EXPECTS project as part of the Aalto Energy Efficiency Programme. The team has invented a novel heat storage material that is able to bring the summer’s heat into the winter time. The material is able to store large amounts of heat as low temperatures and as long time as desired. The stored heat is released from the material in a completely new manner by heating the material slightly. The novel heat storage solution could improve substantially the energy efficiency of solar energy as well as numerous industrial processes. This innovation and team competed in the Helsinki Challenge under the name Team Heatstock and tied for first place in the competition finals. 

heat storage infographic

How could the material be used?

HeatStock’s material is able to retain the stored heat as low temperatures as wanted as long time as wanted without heat losses, whereas the efficiency of "traditional" heat storage, hot water tank, decreases substantially when the environment temperature decreases and storage time becomes longer. The storage volumes above have been calculated for heating a 100 m2 passive house in southern Finland for half a year. 


How does this new material work? 

The storing and releasing of heat is based on melting and crystallization that has been utilized before for short-term storing of heat (heat storage period e.g. one day). In our new solution, heat can be stored several weeks or months. The heat is released by a slight heat pulse that has never been utilized before.


What is the material made of?

The active material of the novel solution is sugar alcohol (analogous to xylitol used in chewing gum). Polymer additive (similar to that used in diapers to absorb moisture) is able to alter the heat storing and releasing properties of sugar alcohol drastically. These novel properties can be exploited in long-term storing of heat. The raw materials of the HeatStock’s solution are affordable and non-toxic.

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