Smart operation with seasonal thermal storage

Seasonal TES entails storing heat or cold when demand is low and then using it months later when demand is high. Possible storage systems include underground water tanks, underground aquifers, adiabatic compressed air and liquid air. Seasonal storage typically requires considerable planning and co-ordination between end-use demands and energy resources, and it is economically viable only when costs are low, given that the storage systems charge or discharge so infrequently.

Seasonal storages make it possible to meet the seasonal heating or cooling demand with renewable energy sources produced months earlier. This can be especially valuable for meeting the expected increases in winter electricity demand amid the greater adoption of heat pumps in district heating networks, homes and other buildings. The electricity generation capacity of district heating systems is often determined based on the winter heat demand. Seasonal storage allows the system to operate with less generation capacity, lowering costs. For example, Sweden’s Arlanda Airport uses seasonal aquifer storage to reduce the energy supply needed from the local district heating system by 10-15 GWh.