Curious Nature: What is geothermal energy, and how can we make use of it? (column)
November 11, 2017
Geothermal energy comes from the internal heat of the Earth. This energy can be harnessed to heat and cool buildings or as a source of electricity.
The inside of the Earth is incredibly hot. Temperatures can reach 7,600 degrees in the Earth's core. These temperatures are hot enough to melt rock and create pockets of magma — hot, molten rock — deep below the Earth's crust. There are also pools of water trapped within the rock below the Earth's surface. The magma surrounding these underground pools heats the water and creates geothermal reservoirs from which geothermal energy is captured.
There are a few different methods used to harness geothermal energy:
Pipe systems can take advantage of geothermal energy in places where geothermal water reservoirs are close to the Earth's surface; these systems transfer the heat from the water into the building's heating system and then send the water back to the reservoirs to be heated again.
Geothermal systems also can use the constant natural temperature of the Earth to heat and cool buildings. The ground just below the Earth's surface remains between 50 degrees and 60 degrees all year long, despite the weather. In winter, when the ground is warmer than the air, liquid sent through underground pipes transfers this heat from the ground into the building's heating system. In the summer, these pipes transfer heat from the building into the much cooler ground.
Finally, geothermal energy can be harnessed and converted into energy on a large scale in power plants. There are three different kinds of geothermal power plants, but according to a recent National Geographic article, most geothermal power plants in the future will be binary plants. Binary plants use a system where the heat from geothermal water is transferred to another liquid, which then turns into vapor and spins turbines, creating energy.
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Geothermal energy has become widely used throughout the world. The first geothermal power plant was built in Italy in 1904, though people have been harnessing geothermal energy through other less technical means, such as geothermal hot springs, for thousands of years. Now many countries are directly using geothermal energy, and 70 percent of countries generating geothermal power are either developing or transitional economies.
Because geothermal energy relies on harnessing heat from inside the Earth, countries with abundant geothermal energy tend to be those located along tectonic plate boundaries, or in geologic hot spots with lots of volcanic activity. Iceland is especially well known for its production and use of geothermal energy, and nearly all of its capital city Reykjavik is heated with geothermal energy.
The largest barrier to implementing geothermal energy is the cost. Geothermal energy production requires expensive initial investments to establish the heating and cooling system. However, after these initial investments, geothermal energy is relatively inexpensive and savings from pump systems often pay for themselves after five to 10 years.
There are many benefits to geothermal energy. It is considered a form of renewable energy because the water removed from the ground is replaced and reheated. Unlike other sources of renewable energy, such as wind or solar, geothermal energy production is not limited by weather conditions, and unlike nuclear or coal power plants, geothermal plants can be run 24 hours a day, if necessary.
Additionally, geothermal energy can be produced without burning fossil fuels, and emissions rates of carbon dioxide are relatively low compared to other sources of energy. Although it isn't 100 percent problem free, geothermal energy has the potential to play a large role in combating climate change and improving living standards around the world.
Kate Oetheimer is a naturalist and sustainability intern at Walking Mountains Science Center in Avon. She also really likes volcanoes.