Heat to cold: Relevance and application of thermally driven cooling for the transformation of the energy system

Cooling of buildings and processes contributes substantially to CO2 emissions, and need for active cooling is rising due to higher temperatures in summer as well as higher comfort needs. Electrically driven vapor compression is the most used technology to supply active cooling. The overall transformation of the energy supply towards close-to-zero CO2 emissions leads to a significant electrification of all sectors which can make any additional electricity use a “marginal user” substituted by fossil energy. In this context, the role of thermally driven technologies needs more significant consideration. Especially in combination with district heating grids fed by renewable sources, sorption cooling offers both technological as well as economical options to significantly reduce the electricity need and thus can help for a faster decrease of CO2 emissions than in purely electricity driven scenarios. Status and findings within the joint project initiative SubSie (Sorption evaporators for temperatures below 0°C) for ab- and adsorption technologies with refrigerant water are discussed. Preliminary results on sublimation from an innovative evaporator for an adsorption chiller show that heat transfer for sublimation is in the same range as for evaporation from the structure.