What are geothermal energy resources?
Heat is a form of energy and geothermal energy is literally the heat contained within the Earth. There are two types of geothermal energy resource trapped underground depending on the water source. Geothermal energy is produced from hot geothermal water already in the ground or water which becomes hot after it is pumped underground. The first type occurs where water has naturally percolated, become heated by the earths heat and become trapped underground in reservoir rocks which hold the geothermal water in natural voids, cavities or fractures in the rocks which are permeable. Permeable means the ability of water to flow through the natural or engineered cavities or fractures in the rocks. The other type of geothermal resource is where underground rocks themselves are very hot but are dry either because of lack of natural voids, cavities or fractures in the rocks which can hold water or lack of water (Hot Dry Rocks) in the rocks.
