Skip to content


HEAT-INSYDE combines three main technologies to advance a thermochemical heat storage system to a compact domestic heat storage prototype at a Technology Readiness Level 7

Multicyclic stable thermochemical material

To achieve a compact system, HEAT-INSYDE will work on further development of potassium carbonate (K2CO3) composites as active storage material, aiming to improve the storage density at particle bed level from 0.7 to 1.0 GJ/m3 (25% porosity). This can be achieved by making the particle shape more regular and optimizing particle sizes. To that end, a particle production process will be developed for manufacturing regular shaped particles with well-defined particles.

Compact thermochemical heat storage systems

The compactness of a thermal storage technology is determined by:

  • the energy density of the storage materials
  • the volume necessary for thermal insulation and for the auxiliary equipment and the volume taken in by voids between the available volume in a house (e.g. for maintenance)
  • the geometry of the storage equipment.

The HEAT-INSYDE storage system will be designed and developed, based on a closed-loop system, in a compact manner by minimizing tubing length and the size of critical components, such as the heat exchanger and the evaporator/condenser units. HEAT-INSYDE aims for an energy density at system level of 0.6 GJ/m3, which is 10 times denser than a 1 m3 water storage tank when considering a storage period of more than 13 days.

Energy management and interfacing

Our Heat batteries function within an energy-ecosystem that is coherent with the local climate-related demands and  configuration (i.e. availability of a heat network and/or electricity grid). For optimal use of a heat battery two challenges must be addressed.

Firstly, flexible interfacing between the heat storage system and the local energy environment will be achieved by operating the closed-loop reactor at variable pressures. This allows to tune the output temperature based on the local available input sources.

Secondly, management systems enabling the use of decentralized heat storage systems to balance the grid will be developed. Energy management scenarios will be implemented in order to assess the role that heat storage solutions can play in alleviating grid issues, focusing on peak load reduction, given the local combination of technologies in the demo sites (including notably heat pumps and solar PV installations).