Geothermal energy is energy that comes from heat produced by magma and radioactive decay of elements generated by tectonic activity. The heat generated from these processes is transferred to water that is deep within the earth, this hot water is then used as a form of geothermal energy. Geothermal energy is referred to as renewable because the water is replenished by rain and the Earth is constantly generating heat.
Usually geothermal energy is deep underground, however some visible signs of above ground include volcanoes, hot springs, geysers, and fumaroles. Geologist use many methods to find geothermal resources and this includes:
– Studying aerial photographs and geological maps.
– Analyzing the chemistry of local waters and concentrations of metals in the soil.
– Measuring variations in gravity and magnetic fields.
– Drilling wells to measure the underground temperature.
The most active geothermal resources are usually found along major plate boundaries where earthquakes and volcanoes are concentrated. Most of the World’s geothermal activity is located along the Ring of Fire.
There are four kinds of geothermal resources:
– Hot dry rock
Hydrothermal is the only kind in wide use,the other three are in the beginning stages of development.
How it works
Residential geothermal heating systems have three main components: a ground loop, a heat pump or furnace, and a means of distributing heat. Essentially, here’s how it works:
1) Polyethylene pipes are built into a ground loop, which can be horizontally or vertically oriented. These pipes must penetrate deeper than the frost line, where the internal temperature is both warm and constant. If you want to heat your home, these pipes extract heat from the soil. If you want to cool your home, they are used to return the heat extracted from your house back to the ground.
2) Your heat pump/furnace system, which is located inside your house, takes the heat delivered by the ground loop and transfers it to the distribution system.
3) The distribution system, which can either be comprised of ductwork or radiant floor heating coils, delivers heat to the interior of your home. You use a thermostat to set the desired heat level, just as you would with a regular propane furnace.
If you want to cool your house instead, simply set the thermostat to the desired level and the entire system will operate in reverse. The distribution system will extract heat from the air, send it back down through the furnace and into the ground loop, where it is returned to the ground.