How Does Geothermal Power Work?

One of the most promising renewable energy sources is that of geothermal power. With the flexibility to be used in many ways, from large and complex power stations to small and relatively simple pumping stations, electrical power from geothermal energy has the potential to be one of the most sustainable sources of energy.

Geothermal simply means “heat from the earth” and there are two basic types of geothermal power. The first is the use of geothermal springs and the second is ground-source heat pumps.

A geothermal power station

The use of steam generated from hot springs or hotspots in the earth’s crust is the most common way of capturing geothermal energy. Several methods are used: the steam may go directly through the electrical turbine; very hot water (not steam) is depressurized or “flashed” into steam to turn the turbine; or, within a closed system hot water may be used to boil a secondary liquid that boils at temperatures lower than water and is converted into steam to drive the turbine.

In all methods the basic concept of geothermal generation is the same: steam turns the turbines to generate electricity. The specific type of method used is dependent upon the type of geothermal resource. Since there are more hot water resources than pure steam resources and the pure steam resources are the easiest to build, the majority of future development of geothermal energy will likely involve the hot water methods.

Geothermal Power Work Second Basic Method

The second basic method to using heat energy from the earth is ground-source heat pumps. This system is used for geothermal heating and cooling for buildings by utilizing the constant year-round temperature (about 50 degrees Fahrenheit) of the soil below the ground surface. This method works on a smaller scale and is more suitable for self-sufficient homes and properties dedicated to permaculture.

The system works by pumping air or antifreeze liquid through pipes that are buried underground and then re-circulated into the building. In the summer, heat is moved from the building and cooled while moving through the ground; in the winter heat is moved from the ground to the building. Some systems use compressors and pumps, similar to electric air conditioning systems, to maximize the heat transfer.

Those residing in areas of temperature extremes or in areas without the use of urban utilizes such as natural gas will certainly find the ground-source heat pump geothermal energy system to be the most energy-efficient, sustainable, and environmentally clean heating/cooling system available. The US Department of Energy found that heat pumps can save a typical home hundreds of dollars in energy costs each year, with the system typically paying for itself in 8 to 12 years.

Geothermal energy is one of the most promising sustainable energy sources and it can provide long-term solutions on both a global and a residential scale. -KATHY FAIRCHILD

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