How Is Geothermal Energy Used Learn Through Thermal Energy Examples

How Is Geothermal Energy Used? – Learn Through Thermal Energy Examples

By: - Environmental - November 30, 2011
how is geothermal energy used learn through thermal energy examples

One of the most common questions that come up when we think about the future of human kind is what will happen when we run out of fossil fuels. Though there is certainly a lot of talk about how important it is to stop being so dependent on non renewable resources, there doesn’t seem to be a huge effort to actually transition our old coal plants, for instance, to greener energy. There are certainly wind farms, for example, scattered about the US, but much of the energy we use in this country comes from non renewable resources like coal, oil and natural gas. Once these resources are gone, they are gone…there is nothing we can do to get them back.

Luckily, for those who are thinking ahead, other forms of energy are out there and one of them is geothermal energy. Thought it has been used for different reasons for thousands of years, geothermal energy comes right from the earth. Deep below the surface of the earth is pressurized steam and hot water that renews constantly and this steam and water can be used to make electricity and power that we desperately need.

There is a lot of heat in the earth and the deeper you dig, the higher the temperature gets. The core of the earth, which is about 4000 miles below the surface, can get as warm as 7600 degrees F (6437 degrees C). The reason the core is so hot is that energy is still there from the moment the earth was made. Additionally, there is radioactive decay that is constantly happening and these reactions cause even more heat than that caused by the creation energy.

The heat at the center of the earth is so hot it actually melts rock and turns the rock into magma, which is what comes out of a volcanic eruption. The same lava you may have seen out of a volcano is the same substance in the center of the earth.  The lava that does not come out of the volcanoes stays underground and heats rock and water that is below the surface. This lava is not hot enough after being insulated by many layers of earth to turn this rock to lava, but it is hot enough to heat the water to several hundred degrees F. This is the water that forms hot springs and geysers. There are also pools under the surface, made of the same water as the hot springs and geysers are, that are called geothermal reservoirs and this is where geothermal energy comes from.

You now know what geothermal energy is and where is comes from, but what about the question “how is geothermal energy used?” To answer to the question “how is geothermal energy used”, you need to know that there is not just one way, but three: direct geothermal energy, geothermal heat pump and geothermal power plant.

The first use of geothermal energy is direct geothermal energy. Simply, this is where homes and offices that are located near natural hot springs or geothermal reservoirs can actually get the hot water pumped directly into a heat exchanger right on site. This heat exchanger takes the heat from the water and displaces it into the building’s heating system. The water itself is sent right back into the hot spring or reservoir where it will be used again, over and over again.

The second use of geothermal energy is geothermal heat pump. This process starts a few feet below the surface of the earth where the water and soil remain constantly at about 55 degrees F. That temperature is just enough to heat and cool buildings. In the cold months, this water is pulled up from the ground and sent through a series of pipes into a building. A compressor and heat exchanger take the heat from the pipes and send it right through the duct system. In the warmer months, a reversal of the process happens and the pipes pull heat away from the building.

The third and final main use of geothermal energy is geothermal power plant. This is where the water from the earth is sent right to an actual power plant and used to generate electricity with turbines and generators. There are three different types of geothermal power plants. They are flash steam plants, dry steam plants, and binary cycle plants.

Flash steam plants are a bit more complicated. The take water that is naturally anywhere from 300 to 700 degrees F and lets that water turn to steam naturally with will spin the turbines. As the steam cools, it turns right back into water and back to the ground.Dry steam plants work by simple steam being piped from the ground into generators. The steam turns the turbines which generates the electricity we need.  The third type of plant, binary cycle plants is even a bit more complicated. This is where hot water from the earth is pumped right into a heat exchanger. The heat is transferred to another liquid, like isobutene, that has a lower boiling point than water.  When the fluid is heated, it turns to steam, just like water does.  This spins the turbines and makes electricity.

Now that you know the answer to “how is geothermal energy used”, you may be interested in a few thermal energy examples. Some have already been mentioned above, like geysers and hot springs. These are geothermal energy examples to be specific. General thermal energy examples would be anything like coal burning, a lit match or even a light bulb because thermal energy is any energy given off by heat.