Geothermal Power Plant

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What is a Geothermal Power Plant?

A geothermal power plant captures and uses the heat from the earth to drive one or more steam turbines that turn one or more  synchronous generators, which generate "carbon free energy," "pollution free power" and "zero emission power."

There are three geothermal power plant technologies being used to convert hydrothermal fluids to electricity. The conversion technologies are dry steam, flash, and binary cycle. The type of conversion used depends on the state of the fluid (whether steam or water) and its temperature. Dry steam power plants systems were the first type of geothermal power generation plants built. They use the steam from the geothermal reservoir as it comes from wells, and route it directly through turbine/generator units to produce electricity. Flash steam plants are the most common type of geothermal power generation plants in operation today. They use water at temperatures greater than 360°F (182°C) that is pumped under high pressure to the generation equipment at the surface. Binary cycle geothermal power generation plants differ from Dry Steam and Flash Steam systems in that the water or steam from the geothermal reservoir never comes in contact with the turbine/generator units.

Renewable Energy Institute
"Changing the Way the World Makes and Uses Energy!"

Austin, Texas

marketing@GeothermalPowerPlant.com

What is the Organic Rankine Cycle?

An Organic Rankine Cycle uses a heated chemical instead of steam as found in the Rankine Cycle. Chemicals used in the Organic Rankine Cycle include freon, butane, propane, ammonia, and the new environmentally-friendly" refrigerants. 

A Rankine cycle is a closed circuit steam cycle. (see www.RankineCycle.com for more information).


Why use a chemical refrigerant? 

A refrigerant boils at a temperature below the temperature of frozen ice. Solar heat, for example, of only 150 degrees Fahrenheit from a typical rooftop solar hot water heater, will furiously boil a refrigerant. The resulting high-pressure refrigerant vapor is then piped to an organic Rankine cycle engine. 


Why is it called "organic"? 

"Organic" is a term used in chemistry to describe a class of chemicals that includes Freon and most of the other common refrigerants.

Types of Geothermal Power Plants

Dry Steam Power Plants

Dry steam power plants at the Geysers in California.

Steam plants use hydrothermal fluids that are primarily steam. The steam goes directly to a turbine, which drives a generator that produces electricity. The steam eliminates the need to burn fossil fuels to run the turbine. (Also eliminating the need to transport and store fuels!) This is the oldest type of geothermal power plant. It was first used at Lardarello in Italy in 1904, and is still very effective. Steam technology is used today at The Geysers in northern California, the world's largest single source of geothermal power. These plants emit only excess steam and very minor amounts of gases.

Dry Steam Power Plant

Flash Steam Power Plants

Hydrothermal fluids above 360°F (182°C) can be used in flash plants to make electricity. Fluid is sprayed into a tank held at a much lower pressure than the fluid, causing some of the fluid to rapidly vaporize, or "flash." The vapor then drives a turbine, which drives a generator. If any liquid remains in the tank, it can be flashed again in a second tank to extract even more energy.

Flash Steam Power Plant

Binary-Cycle Power Plants

Most geothermal areas contain moderate-temperature water (below 400°F). Energy is extracted from these fluids in binary-cycle power plants. Hot geothermal fluid and a secondary (hence, "binary") fluid with a much lower boiling point than water pass through a heat exchanger. Heat from the geothermal fluid causes the secondary fluid to flash to vapor, which then drives the turbines. Because this is a closed-loop system, virtually nothing is emitted to the atmosphere. Moderate-temperature water is by far the more common geothermal resource, and most geothermal power plants in the future will be binary-cycle plants.

Binary Cycle Power Plant

The Future of Geothermal Electricity

Steam and hot water reservoirs are just a small part of the geothermal resource. The Earth's magma and hot dry rock will provide cheap, clean, and almost unlimited energy as soon as we develop the technology to use them. In the meantime, because they're so abundant, moderate-temperature sites running binary-cycle power plants will be the most common electricity producers.

Before geothermal electricity can be considered a key element of the U.S. energy infrastructure, it must become cost-competitive with traditional forms of energy. The U.S. Department of Energy is working with the geothermal industry to achieve $0.03 to $0.05 per kilowatt-hour. We believe the result will be about 15,000 megawatts of new capacity within the next decade.

Some of the above information provided with our thanks by the Department of Energy.

What is Geothermal Heating and Cooling?

Geothermal heating and cooling is the technology that uses the free and available heat from the earth to provide heating and/or cooling for a home, business, industry or industrial process.

What is a Geothermal Heat Pump?

Geothermal heat pumps, also known as the ground source heat pumps, are highly efficient renewable energy technologies that is gaining wide acceptance for both residential and commercial buildings. 

Geothermal heat pumps are used for space heating and cooling, as well as water heating. Its great advantage is that it works by concentrating naturally existing heat, rather than by producing heat through combustion of fossil fuels.

The technology relies on the fact that the Earth (beneath the surface) remains at a relatively constant temperature throughout the year, warmer than the air above it during the winter and cooler in the summer - very similar to a cave. 

The geothermal heat pump takes advantage of this by transferring heat stored in the Earth or in ground water into a building during the winter, and transferring it out of the building and back into the ground during the summer. The ground acts as a "heat source" in winter and a "heat sink" in summer.

The system includes three principal components:

• Geothermal earth connection subsystem

• Geothermal heat pump subsystem

• Geothermal heat distribution subsystem.

"Earth Coupled"

Another term used to describe homes and buildings using geothermal heat pumps is that they are "Earth coupled" in that they are using the Earth as a heat source (in winter) and a heat sink in the summer.  The Earth coupled system uses a series of pipes, commonly called a "loop" which is buried in the ground near the building to be heated or cooled.  The loop can be buried either vertically or horizontally. It circulates a fluid (water, or a mixture of water and antifreeze) that absorbs heat from, or gives heat to, the surrounding soil, depending on whether the ambient air is colder or warmer than the soil.

Heat Pump Subsystem

For heating, a geothermal heat pump removes the heat from the fluid in the Earth connection, concentrates it, and then transfers it to the building. For cooling, the process is reversed.

Heat Distribution Subsystem

Conventional ductwork is generally used to distribute heated or cooled air from the geothermal heat pump throughout the building.

Residential Hot Water

In addition to space conditioning, geothermal heat pumps can be used to provide domestic hot water when the system is operating. Many residential systems are now equipped with desuperheaters that transfer excess heat from the geothermal heat pump's compressor to the house's hot water tank. A desuperheater provides no hot water during the spring and fall when the geothermal heat pump system is not operating; however, because the geothermal heat pump is so much more efficient than other means of water heating, manufacturers are beginning to offer "full demand" systems that use a separate heat exchanger to meet all of a household's hot water needs. These units cost-effectively provide hot water as quickly as any competing system.

What is Renewable Heating and Cooling?

Renewable heating and cooling is the technology that uses one of the free or nearly-free renewable energy resources, such as geothermal, solar or biomass, for the generation of heating and/or cooling for a home, business, industry or industrial process.

Renewable Energy Institute
"Changing the Way the World Makes and Uses Energy!"

Austin, Texas

marketing@GeothermalPowerPlant.com

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Geothermal Power Plant
www.GeothermalPowerPlant.com

Austin, Texas

marketing@GeothermalPowerPlant.com

Renewable Energy Institute

GeothermalPowerPlant.com

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