During the warm months, cold saltwater from beneath the city could be pumped to the surface and heated by factories, waste incinerators, gas plants, and surplus renewable energy. It would subsequently be injected at a different location below the clay strata for heat storage.
As the winter approached, pumping the heated saltwater up from storage to the surface would enable the thermal energy to be withdrawn for heating distribution. The cooled saline solution could then be pumped back into the aquifer from which it had been originally taken.