Geothermal energy is the heat of the Earth. Using drills, we can pull from the essentially limitless supply of heat that the Earth has. Unlike other types of renewable energy that we have talked about, geothermal energy has two different purposes. Geothermal heat pumps pump heat directly into homes or buildings. Geothermal power plants convert heat to electricity.
How does it work?
At normal geothermal energy power plants, wells are drilled into the ground to bring geothermal energy from the surface. They are generally about 1-2 miles deep. Power plants are likely to be found near an area that has a lot of hot springs, geysers, or volcanic activity because these are places where the Earth is particularly hot just below the surface. Water is pumped into the surface through the well. This water is heated up when it is inside the Earth's crust. Once it is sufficiently heated, the hot water is brought back up via another pipe. The hot, pressurized heated water is allowed to expand, which generates rotational and mechanical energy to turn turbines to generate electricity. The water is then pumped back into the surface to start the process over again.
At geothermal heat pumps, water or another refrigerant moves through a loop of pipes. When the weather is cold, the water or refrigerant heats up when it goes through the parts of the pipes that are underground. When the weather is hot, the water or refrigerant cools down when it goes through the ground. Once the water or refrigerant gets back above ground, it transfers heat or coolness into the building. The water or refrigerant cools down or heats back up (the opposite of what happened when it went underground before) and is ready to restart the process.
How is this renewable energy?
This is renewable energy because the geothermal heat of the Earth will never run out. Also, the water is pumped right back into the Earth so that that process can restart. Therefore, the water will never run out in both processes. This is clean energy because it does not require any burning of fossil fuels.
The Controversy of Geothermal Energy
While geothermal energy is renewable, there is a lot of controversy with geothermal energy. One is the fact that you have to drill into the Earth. Some people think that this is an act against nature. This is a very serious concern. Also, when drilling, the machinery used releases greenhouse gases. This causes controversy as to if geothermal energy really is a climate solution.
The Presence of Geothermal Energy in America and the Rest of the World
The majority of people in Iceland are using geothermal heat pumps to heat their homes. However, the highest potential of geothermal energy is in the Ring of Fire. That is because hot magma is very close to the surface there.
In the United States, geothermal energy generates 0.4% of the total electricity generated. It produced 14% of the Philippines total energy, which is a significant amount.
The Cost of Geothermal Heat Pumps
While there are many people who think that geothermal heat pumps must cost a significant amount more than traditional dirty energy heating and cooling systems, it actually doesn't. While the cost may be slightly more during the installation phase, the savings have been measured to 50%-75%. In addition, the government offers tax credit programs for geothermal energy installation.
The Cost of Geothermal Power Plants
Geothermal heat pumps can be installed in your home. That is the only way that they can be installed. However, geothermal power plants can't really be installed in your home. To get energy from a geothermal power plant, you would have to get it from a renewable energy provider, just like your current energy provider (most likely a dirty energy one; ConEdison, Pacific Gas & Electric, Southern California Edison, PowerSouth, etc.), but it generates energy from renewable energy. Renewable energy providers are generally cheaper than dirty energy providers.