In San Antonio he recently designed and installed a system that uses a swimming pool as a geothermal source, combined with a cooling tower.
Mac Word writes:
You can see the gray tower installed with the pool equipment. The water is piped to the remote heat pump modules on either side of the house. In the house are conventional heat pump air handlers, so when the unit is working in the cooling mode the heat is transferred to the pool thus providing free pool heat in the shoulder times of the year. When the pool gets to the desired temperature, the cooling tower and the pump starts and the tower keeps the pool at the desired temperature for the balance of the cooling season. In the winter the units pull heat from the pool to heat the house just like (a geothermal system with pipes in deep holes). The earth contact with the pool plus the solar gain replenish the heat energy in the pool.The cooling tower part of the system, inspired by large commercial systems, can use condensate generated by the heat pump to account for 1/2 the water use at peak. Rainwater and brackish water can also be used.