Surface geothermal energy applied to low cost and low power consumption residential air conditioning

The operation of an air-conditioning system, completely powered by geothermal energy, with no other external energy input and no heat pump is described in this paper. This geothermal system can contribute to the reduction of electricity consumption in residences and small businesses, and can retrofit any installation, since it is a surface geothermal energy installation. That is possible because soil temperature, to a certain depth, has a constant temperature throughout the year, with a large mass and heat capacity. Practical tests can be easily conducted with water and underground heat exchangers. This system is designed with a coolant circulating within a serpentine driven by a small hydraulic pump. If the temperature inside the residence is lower or higher than the soil temperature, there is heat exchange between the residence ambient and the soil. Therefore, the surface geothermal energy is used to warm-up or cool-down the room ambient. The prototype described in this paper was implemented with an electronic control to maximize the performance of the heat exchangers. Experiments were made during four months in the winter and in the summer.