In geology, geothermics is the study of latent heat that is concentrated deep inside the earth. Underneath your feet, at a depth of approximately fifty to sixty miles below, lies a viscous goo of hot molten rock. The deeper inside the earth you go, the hotter it gets. Occasionally, this molten rock erupts out of the earth through volcanoes and fissures as a result of overpressurization. This sub-field of geology is called volcanology.
Geothermics becomes very important when seeking an alternative to today's finite fossil fuels. By harnessing the natural heat energy inside the earth, scientists believe geothermal energy holds promise in adding to our growing mix of alternative energy sources.
Today, geothermal energy provides approximately one percent of the world's power. The world's largest geothermal plant complex, The Geysers, is located due north of San Francisco, California and produces electricity for numerous cities and counties on the West coast. Other countries including Iceland, Portugal, Philippines, Australia, Mexico, and the United Kingdom have built geothermal energy plants as well that are producing clean, renewable energy even as we speak.
The main drawback to geothermal energy is that, like petroleum, it is limited to geography. With the exception of enhanced geothermal systems (hot-dry-rock geothermal systems) that pump water into hot subterranean rock rather than using naturally occurring hot water near the earth's surface, geothermal plants must be located on top of active geothermal fields.
In Iceland, geothermal energy is widely used because of the many volcanoes and geothermal fields in that country. Not only are a majority of Icelandic homes heated using geothermal energy, but almost one-third of the total energy consumed is derived from geothermal sources with hydro-electric power assuming nearly all the rest. Unlike the fossil-fuel dependent United States, Iceland's energy mix is heavily weighted toward renewable forms of energy.
Despite its shortcomings, geothermal energy is an important element of the world's current energy mix that, when combined with solar and other forms of renewable energy, helps wean us from dependence on foreign (often volatile) sources of non-renewable energy.