“Geo” means “from the earth,” and “thermal” means “heat,” so this type of energy is found under the earth. The hot lava from a volcano and the hot steam from a geyser both come from underground heat, and we can use that same type of heat in our homes and at school. The system pumps a liquid through the pipes to absorb the heat and to bring it back indoors. A device called a “heat exchanger” takes the heat from the liquid and uses it to heat the air inside the building. A geothermal system can cool your building during the summer as well. It just works in reverse, absorbing the heat from the air inside your home and moving to back into the earth. A geothermal heater is also very energy efficient. Almost none of the energy used is wasted, so it helps keep heating bills very low during the winter.
The chart shows cumulative installed geothermal power capacity for ten countries with the largest geothermal resource. Although the geothermal resource is global, the resource does not come to the surface in all locations. What conclusions can you draw about the countries on this list?
Behind the Technology
Large buildings, such as schools, use vertical geothermal heat pumps to trade the heat between the building and the subsurface. Fluid from the heat pump circulates through the underground pipes trading heat for the relative cold of the subsurface in summer and cold for the relative warmth of the subsurface in the winter. Vertical systems require less land area than horizontal systems.