Geothermal energy is a source of natural energy that is derived directly from the earth. It is the energy found in the natural heat of the ground and water sources that occur naturally. Examples of geothermal energy include hot springs and magma. Current technology doesn’t utilize geothermal energy to its full potential—for example, there are no current commercial applications of geothermal energy derived from the hot dry rock that is found three to six miles below the Earth’s surface and a feasible method of extracting the geothermal energy found in magma has yet to be discovered. This is an unfortunate reality, particularly because magma is the most powerful resource for geothermal energy.
Despite this, a number of methods of extracting geothermal energy have already been developed with more on the way: geothermal electricity production, geothermal direct use, and geothermal heating from heat pumps.
Geothermal Electricity Production
Geothermal electricity production is a method of generating energy using the geothermal energy in the earth. Steam is an important ingredient used in the generation of electricity in most power plants. Steam is used to rotate the turbine which activates the generator that produces the electricity. Fossil fuels are sometimes used in power plants in the reaction which converts water to steam through boiling. However, geothermal power plants are considered to be more environmentally friendly, in that they use steam extracted from reservoirs of naturally occurring hot water found below the Earth’s surface.
Geothermal power plants produce electricity using geothermal energy. There are three main types of geothermal power plants: dry steam, flash steam, and binary cycle.
Dry steam power plants use steam that comes from underneath the ground. Using a piping system, the steam is directly transported to the turbine/generator unit. In the United States, there are only two natural sources of steam: The Geysers in California, and ‘Old Faithful’, the geyser found at Yellowstone National Park. Yellowstone is protected by environmental laws meaning that the steam from Old Faithful cannot be extracted, so the only dry steam plants in America operate close to The Geysers.
Flash steam power plants are the most common type of geothermal power plants. They take advantage of geothermal reservoirs; in other words, flash steam power plants make use of the hot water underneath the earth and then convert it into steam using decreasing pressure and separation methods. The steam separates from the water and is then directed to the turbine/generator unit. This is a particularly useful method, because the leftover water and condensed steam are sent back to the reservoir, making it a sustainable method of producing electricity by using geothermal energy.
Binary cycle power plants are a little different. They use the hot water from the earth to boil a working fluid. This is usually some form of an organic compound that has a low boiling point. This substance is turned into a vapor in what’s known as a ‘heat exchanger’. It is this vapor, and not the water from the earth itself, that is used to turn the turbine in order to power the generator. After this process has taken place, the water is injected back into the earth in order to be reheated.
Geothermal Direct Use
Geothermal direct use is the term used to describe using geothermal energy in its entirely natural state. In other words, there is no chemical process that takes place: the energy comes directly from the source and is used as such.
Using geothermal energy in this manner has been done for thousands of years, with people historically using hot springs for a variety of purposes from bathing to cooking to cleaning game. Nowadays, hot springs are often used as spas, but there are other more sophisticated ways of using geothermal energy directly.
Modern systems drill a well into a geothermal reservoir. This well, coupled with a mechanical system that includes piping, controls, and a heat exchanger, provides a steady supply of hot water. Thus, in this manner, the geothermal energy is delivered directly for its intended use.
Hot water that occurs naturally underneath the Earth’s surface has many uses, including the heating of buildings, helping to maintain moisture and humidity conditions in greenhouses, drying crops through processes of evaporation, maintaining the water temperature at fish farms, and even industrial processes that are as complex as pasteurization.
Geothermal Heating and Your Home
Geothermal heating from heat pumps is the most relevant form of geothermal energy extraction that can be used in the home. The other two types of geothermal energy extraction are limited to certain areas in the United States. This is due to the location of geothermal reservoirs. Most of these reservoirs, which are necessary for geothermal electricity production and geothermal direct use, are located in the Western states, Alaska, and Hawaii.
Conversely, geothermal heating from heat pumps can be done pretty much anywhere in America, because the process makes use of the naturally occurring temperatures of the upper ten feet of the earth. This method of using geothermal energy takes advantage of the constant temperature of this shallow ground. This process doesn’t require the natural hot water in the earth, just the temperature itself.
Geothermal heat pump systems have three main parts: the heat pump unit, the ground heat exchanger, and the ductwork or air delivery system. These systems can both heat and cool buildings because the temperature of the ground corresponds to the season— retain heat in the winter, and remain cool in the summer. In essence, they acts as a naturally occurring air conditioning system able to maintain a constant, comfortable temperature for your home.
The heat exchanger in a geothermal system is a network of pipes buried in the ground near the building that needs the heating or cooling. A liquid is transported through the pipes in order to absorb the surrounding heat in the nearby ground.
In winter, the heat pump takes heat from the heat exchanger and pumps it around your home. This process is reversed in the summer: the heat pump takes heat from the air in the home and passes it back into the heat exchanger. This excess heat is a method of obtaining a free source of hot water.
Geothermal Heating and Cooling Systems
Geothermal systems are an innovative energy system for your home. They use much less energy than more traditional heating systems, largely because of their heat extraction that simply draws heat from the ground. Choosing a geothermal heat pump for your home can save you money on the cost of heating and cooling your home. Moreover, heat extraction of this kind, because it doesn’t involve processes that require fossil fuels, is better for the environment. The best thing is that this form of geothermal energy use is available across America, because all areas in this country have nearly constant temperatures that occur in shallow ground.
If considering a geothermal system for your home, call Presidential Heating & Air Conditioning today 301-900-5559 to speak with one of our HVAC experts about geothermal options for your home.