Geothermal Energy – Using the Earth’s Natural Heat

Geothermal energy is the heat stored beneath the earth's surface. It is generated 4,000 miles below the surface at the earth’s core, where a fiery 4 billion-year accumulation of dust and gas has naturally produced temperatures that reach over 9,000 degrees Fahrenheit.

The water beneath the earth’s surface absorbs the heat from the core.  Wells dug deep into the earth and special geothermal heat pumps bring the hot underground water or steam to the surface to produce electricity or provide indoor heating.

In order to keep the energy renewable, the water is sent back down an injection well to the geothermal reservoir to maintain pressure and preserve the reservoir.  Additionally, rainfall replenishes underground water sources.

Benefits of using Geothermal Energy

  • • Clean energy - It emits low levels of carbon dioxide. A geothermal field produces less than one-sixth of the carbon dioxide emissions that a clean natural-gas-fueled power plant will produce and very little nitrous oxide or sulfur-bearing gases. Geothermal power plants are clean enough to be built in the middle of farm crops and forests.

  • • Uses less land area than other types of power plants

  • • Reliable source of energy that can be derived 24/7 with less disruption from environmental conditions. Geothermal power plants have average availabilities of 90% or higher as compared to 75% availability with coal plants.

  • • Affordable - A geothermal power plant built with today’s technology would require only 5 cents per kilo watt hour.

  • • Geothermal energy does not depend on foreign oil.

What is Geothermal energy used for?

  • • Direct use of geothermal power – using hot water from the earth for purposes that include hot spring or health spa baths, heating buildings through district heating systems, growing crops, drying lumber, fruits and vegetables, shortening the time needed to grow fish, shrimp and abalone to maturity, pasteurizing milk and use under roads and sidewalks to keep them from icing over in the winter.

  • • Geothermal power plants - drilling deep underground into hydrothermal resources to use hot steam to turn generator turbines that produce electricity.

  • • Geothermal heat pumps - use constant temperatures in upper part of the earth’s surface to heat and cool buildings. (The U.S. Environmental Protection Agency deems geothermal heat pumps as the most energy-efficient, clean, and cost-effective systems for temperature control)

Can you use geothermal energy anywhere?

Reservoirs of steam or hot water are geothermal resources.  These reservoirs are typically found along major plate boundaries that produce volcanoes and earthquakes.  The area that rims the Pacific Ocean is called the Ring of Fire due in part to its underground heat and maintains good geothermal reservoirs.  In the U.S., the western states, Hawaii and Alaska offer the best hydrothermal resources

But if you live in the eastern U.S., do not dismiss geothermal energy as a viable option, because geothermal heat pumps and direct-use applications can harness the earth’s heat from almost anywhere.  Future advances in geothermal drilling technology will allow us to better capture energy from hot dry rock and magma.

Geothermal Energy Resources