Geothermal Energy

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Nesjavellir Geothermal Power Station in Iceland


Geothermal Energy, energy that comes from beneath the surface of the earth. Geothermal energy is not a new source of energy matter of fact it was used to keep the water hot in hot springs. The new bit is the application and conversion of this energy into something more useful that heating a body of water. Such as generating electricity which seem to be the most practical application in the modern world. Once the earth's heat energy is converted into electricity it can be applied to just about anything


Energy stored within the earth comes from nuclear decay of radioactive particles, these reactions create temperatures higher than the surface of the sun inside the earth. Heat is also generated from planetary acceleration. This heat energy can be captured and applied to generate electricity, heat pools, temperature control of buildings. Geothermal energy is considered a renewable source of energy due to the extraction process extracting a tiny amount of energy compared to the heat energy within the interior of the planet.

There are quite a few advantages of utilizing geothermal
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Tectonic Boundries where Geothermal Energy Plants are commonly found.
energy over other forms. First and foremost it is safe, there is really no hazard or waste generated from geothermal energy power plants. Compared to nuclear power plants, in which the spent fuel poses a hazard and potential for accidents which leave a region uninhabitable make geothermal energy the choice. There is no fuel cost associated with operation of a power plant only start up costs which include just construction of the plant itself which is presently somewhat expensive. With advances in the future in technology geothermal energy might be applicable on a large scale. Geothermal energy plants were generally limited to areas near tectonic boundaries but can be really found anywhere due to advances in technology. One more advantage of geothermal energy is that the energy that is being extracted is always there. There is no minimum wind speed or electricity generation on windy days (in comparison to windmills). Rain or shine energy will be produced (in comparison to solar panels). In the near future it wouldn't be surprising if geothermal energy becomes what fossil fuels have become today.

“Geothermal has minimal land and freshwater requirements. Geothermal plants use 3.5 square kilometres per gigawatt of electrical production (not capacity) versus 32 and 12 square kilometres for coal facilities and wind farms respectively. They use 20 litres of freshwater per MW·h versus over 1000 litres per MW·h for nuclear, coal, or oil.” - "Characteristics, Development and utilization of geothermal resources", Geo-Heat Centre Quarterly Bulletin (Klamath Falls, Oregon: Oregon Institute of Technology)

The current status of geothermal energy accounts for 0.3% of
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Red curve represents installed generating capacity, Green Curve is the actual production.
world wide consumption of electricity. The United States is the leading nation of utilization of geothermal energy, however, it is only a fraction of the nations energy sources. Energy output is increasing about three percent annually and is expected to rise even faster in the near future. The energy that can be extracted from using geothermal energy is predicted to be far larger than the current world wide consumption of energy.




The process of converting geothermal energy into electricity is fairly simple and general, the complications arise in the actual construction. There are three types of power plants that can convert the earth's thermal energy into electricity.
  • Dry Steam: Steam is lead by pipes from the interior of the earth to the surface of the earth which then have the energy to turn a generator turbine.
  • Flash Steam: Same principle as dry steam power plants except that the water used (which has condensed after driving the turbine) is recycled and reinserted into the earth to be vaporized again.
  • Binary Cycle: Hot water from the geothermal reservoir is used to heat a different liquid by convection and the second liquid is vaporized and used to turn the generator turbine.

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Generalized Diagram of a Geothermal Powerplant


Bottom line: Geothermal energy is a clean, independent source of renewable energy in which there is a large potential for. It wouldn't be surprising if in the near future geothermal energy becomes a norm for the modern world.

Further Reading: See Characteristics, Development and utilization of geothermal resources Lots of interesting information relating to geothermal energy.

How stuff works: Geothermal Energy

More Interesting Facts about Geothermal
-Geothermal energy is one of the biggest investments made when the obamma administration passed the American Recovery and Reinvestment Act.


- It is estimated that 288 geothermal power projects in fifteen states have the potential to provide up to 8000 megawatts of electricity.

-Vulcan Power co. recently securent a $108 million dollar investment in a geothermal power plan in Nevada.

-This is a speech by our president addressing all the different energy options. I just thought it would be cool for anyone who is interested.

Geothermal Basics

What Is Geothermal Energy?

The word geothermal comes from the Greek words geo (earth) and therme (heat). So, geothermal energy is heat from within the Earth. We can recover this heat as steam or hot water and use it to heat buildings or generate electricity.
Geothermal energy is a renewable energy source because the heat is continuously produced inside the Earth.

Geothermal Energy Is Generated Deep Inside the Earth

Image of the earth's interior, from the outside to the inside, with the crust, the mantle of magma and rock, the outer core of magma, and the innermost core of iron.
Image of the earth's interior, from the outside to the inside, with the crust, the mantle of magma and rock, the outer core of magma, and the innermost core of iron.

Source: Adapted from a National Energy Education Development Project graphic (Public Domain)
Geothermal energy is generated in the Earth's core. Temperatures hotter than the sun's surface are continuously produced inside the Earth by the slow decay of radioactive particles, a process that happens in all rocks. The Earth has a number of different layers:
  • The core itself has two layers: a solid iron core and an outer core made of very hot melted rock, called magma.
  • The mantle surrounds the core and is about 1,800 miles thick. It is made up of magma and rock.
  • The crust is the outermost layer of the Earth, the land that forms the continents and ocean floors. It can be 3 to 5 miles thick under the oceans and 15 to 35 miles thick on the continents.

The Earth's crust is broken into pieces called plates. Magma comes close to the Earth's surface near the edges of these plates. This is where volcanoes occur. The lava that erupts from volcanoes is partly magma. Deep underground, the rocks and water absorb the heat from this magma. The temperature of the rocks and water gets hotter and hotter as you go deeper underground.
People around the world use geothermal energy to heat their homes and to produce electricity by digging deep wells and pumping the heated underground water or steam to the surface. We can also make use of the stable temperatures near the surface of the Earth to heat and cool buildings.
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Where Geothermal Energy is Found

Image of a map of the world titled Ring of Fire. The ring of fire goes around the edges of the Pacific. The map shows that volcanic activity occurs around the Pacific rim.
Image of a map of the world titled Ring of Fire. The ring of fire goes around the edges of the Pacific. The map shows that volcanic activity occurs around the Pacific rim.

The ring of fire goes around the edges of the Pacific. The map shows that volcanic activity occurs around the Pacific rim.
Source: National Energy Education Development Project (Public Domain)
Naturally occurring large areas of hydrothermal resources are called geothermal reservoirs. Most geothermal reservoirs are deep underground with no visible clues showing above ground. But geothermal energy sometimes finds its way to the surface in the form of:
  • Volcanoes and fumaroles (holes where volcanic gases are released)
  • Hot springs
  • Geysers

Most Geothermal Resources Are Near Plate Boundaries

The most active geothermal resources are usually found along major plate boundaries where earthquakes and volcanoes are concentrated. Most of the geothermal activity in the world occurs in an area called the Ring of Fire. This area encircles the Pacific Ocean.
U.S. Geothermal Resource Map
U.S. Geothermal Resource Map
U.S. Geothermal Resource Map
Click to enlarge »
Source: U.S. Department of Energy, Energy Efficiency & Renewable Energy
When magma comes close to the surface, it heats ground water found trapped in porous rock or water running along fractured rock surfaces and faults. These features are called hydrothermal. They have two common ingredients: water (hydro) and heat (thermal).
Geologists use various methods to look for geothermal reservoirs. Drilling a well and testing the temperature deep underground is the most reliable method for finding a geothermal reservoir.

U.S. Geothermal Is Mostly in the West

Most of the geothermal reservoirs in the United States are located in the western States and Hawaii. California generates the most electricity from geothermal energy. "The Geysers" dry steam reservoir in northern California is the largest known dry steam field in the world and has been producing electricity since 1960.
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Use of Geothermal Energy

Some applications of geothermal energy use the Earth's temperatures near the surface, while others require drilling miles into the Earth. The three main uses of geothermal energy are:
  • Direct use and district heating systems use hot water from springs or reservoirs near the surface.
  • Electricity generation power plants require water or steam at very high temperature (300° to 700°F). Geothermal power plants are generally built where geothermal reservoirs are located within a mile or two of the surface.
  • Geothermal heat pumps use stable ground or water temperatures near the Earth's surface to control building temperatures above ground.

Direct Use of Geothermal Energy

There have been direct uses of hot water as an energy source since ancient times. Ancient Romans, Chinese, and Native American cultures used hot mineral springs for bathing, cooking, and heating. Today, many hot springs are still used for bathing, and many people believe the hot, mineral-rich waters have natural healing powers.
After bathing, the most common direct use of geothermal energy is for heating buildings through district heating systems. Hot water near the Earth's surface can be piped directly into buildings and industries for heat. A district heating system provides heat for 95% of the buildings in Reykjavik, Iceland.
Industrial applications of geothermal energy include food dehydration, gold mining, and milk pasteurizing. Dehydration, or the drying of vegetable and fruit products, is the most common industrial use of geothermal energy.

The United States Is the Leader in Geothermal Power Generation

The United States leads the world in electricity generation with geothermal power. In 2008, U.S. geothermal power plants produced 14.86 billion kilowatt-hours, or 0.4% of total U.S. electricity generation. Seven States have geothermal power plants:
  • California has 34 geothermal power plants, which produce almost 90% of U.S. geothermal electricity.
  • Nevada has 16 geothermal power plants.
  • Hawaii, Idaho, Montana, and Utah each have one geothermal plant.
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Geothermal Power Plants

A Geothermic Power Station
A geothermic power station.
A geothermic power station.

Source: Stock photography (copyrighted)
Geothermal power plants use hydrothermal resources that have two common ingredients: water (hydro) and heat (thermal). Geothermal plants require high temperature (300°F to 700°F) hydrothermal resources that may come from either dry steam wells or hot water wells. We can use these resources by drilling wells into the Earth and piping the steam or hot water to the surface. Geothermal wells are one to two miles deep.

Types of Geothermal Plants

There are three basic types of geothermal power plants:
  • Dry steam plants use steam piped directly from a geothermal reservoir to turn the generator turbines. The first geothermal power plant was built in 1904 in Tuscany, Italy, where natural steam erupted from the Earth.
  • Flash steam plants take high-pressure hot water from deep inside the Earth and convert it to steam to drive the generator turbines. When the steam cools, it condenses to water and is injected back into the ground to be used over and over again. Most geothermal power plants are flash steam plants.
  • Binary cycle power plants transfer the heat from geothermal hot water to another liquid. The heat causes the second liquid to turn to steam which is used to drive a generator turbine.
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Geothermal Heat Pumps

Using the Earth's Constant Temperatures for Heating and Cooling

While temperatures above ground change a lot from day to day and season to season, temperatures 10 feet below the Earth's surface hold nearly constant between 50° and 60°F. For most areas, this means that soil temperatures are usually warmer than the air in winter and cooler than the air in summer. Geothermal heat pumps use the Earth's constant temperatures to heat and cool buildings. They transfer heat from the ground (or water) into buildings in winter and reverse the process in the summer.

Geothermal Heat Pumps Are Energy Efficient and Cost Effective

According to the U.S. Environmental Protection Agency (EPA), geothermal heat pumps are the most energy efficient, environmentally clean, and cost effective systems for temperature control. Although most homes still use traditional furnaces and air conditioners, geothermal heat pumps are becoming more popular. In recent years, the U.S. Department of Energy and the EPA have partnered with industry to promote the use of geothermal heat pumps.
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Geothermal Energy & the Environment

The environmental impact of geothermal energy depends on how it is being used. Direct use and heating applications have almost no negative impact on the environment.
Grand Prismatic Spring, Yellowstone National Park, Wyoming
Grand Prismatic Sprinag, Yellowstone National Park, Wyoming
Grand Prismatic Sprinag, Yellowstone National Park, Wyoming

Source: Stock photography (copyrighted)

Geothermal Power Plants Have Low Emission Levels

Geothermal power plants do not burn fuel to generate electricity, so their emission levels are very low. They release less than 1% of the carbon dioxide emissions of a fossil fuel plant. Geothermal plants use scrubber systems to clean the air of hydrogen sulfide that is naturally found in the steam and hot water.
Geothermal plants emit 97% less acid rain-causing sulfur compounds than are emitted by fossil fuel plants. After the steam and water from a geothermal reservoir have been used, they are injected back into the Earth.

Many Geothermal Features Are National Treasures

Geothermal features in national parks, such as geysers and fumaroles in Yellowstone National Park, are protected by law, to prevent them from being disturbed. --By: Fatima Khan
Website: http://tonto.eia.doe.gov/kids/energy.cfm?page=geothermal_home-basics-k.cfm