What is Geothermal Energy and How Does it Work?
Geothermal energy is heat originating deep within the earth. It’s considered a form of renewable energy because the supply is virtually limitless. It’s sustainable, clean, environmentally friendly, and easy to harness.
There are two primary areas in which we can take advantage of geothermal energy.
1) Heating and cooling. Using the stable temperatures directly beneath the surface to heat in the winter or cool in the summer. This is the simplest, most used, and most readily available form of geothermal energy.
2) Producing electricity. Drilling deep into the Earth to bring extremely hot hydro-fluids to the surface and harnessed by turbines. Only large power plants with specialized equipment and an ideal location can effectively tap into this power source.
** Technically, the underground heat source is the sun, so in a roundabout way it’s actually solar energy. This differs from geothermal power production since the sun doesn’t have any effect two miles below the surface.
Geothermal Heat Pump
Natural Heating and Cooling
Geothermal heating and cooling, or geo-exchange, is available to most people around the world regardless of location or climate. It’s a simple, cheap, and efficient method to heat and cool homes and commercial buildings.
Geo-exchange relies on the stable temperatures anywhere from about 6 feet to 20 feet underground. Temperatures underground always remains constant no matter how hot or cold it is at the surface. Depending on where you live, the temperature will usually be around 40-70 degrees Fahrenheit.
Relatively speaking, when it’s cold outside, the temperature underground will be warmer. When it’s hot outside, the temperature underground will be cooler.
So how can we use these constant underground temperatures to heat and cool our homes?
A geothermal heat pump (also known as a ground source heat pump) transfers temperatures to or from the ground to reach the desired climate.
Geothermal Power Production
Further, they leave little impact on the environmental, don’t require raw fuel, and have zero transportation costs.
Geothermal power plants harness the extreme heat from below the Earth’s surface. This heat comes from liquid heated by magma deep within the Earth. We reach this liquid by drilling deep into the earth (1 or 2 miles) and letting the natural pressure push it up to the surface.
The hydrothermal liquid needs to reach at least 300° F to produce enough steam for the turbine. The deeper the well, the hotter the temperature.
When the liquid reaches the surface as steam, it feeds into a turbine generator for electricity generation. Any remaining hot water is “flashed” (reducing pressure and forcing evaporation) to get more steam to feed into the turbine. This process fully utilizes all of the available geothermal resources.
A geothermal power plant can be an effective means of producing electricity under the right circumstances, but they can also have some critical drawbacks.
They must be located in strategic areas that allow for easy access to geothermal reservoirs. On top of that, there’s always the possibility of the well drying up. The tectonic plates can shift at any time and render a plant useless.
Also, the operation must be of considerable size to make it economical. Because of these factors, the number of suitable sites is limited. Even so, there is still plenty of room for growth in geothermal electricity production systems.
The United States is currently the largest producer of geothermal energy in the world, although it only accounts for about .4% of our total power production.
According to a recent geothermal resource assessment from the U.S. Energy Information Administration, “nine western states together have the potential to provide over 20 percent of national electricity needs.”
Unfortunately, costs are still too high for geothermal energy businesses to compete with fossil fuels and other renewable energy alternatives for the time being.