Ten thousand years ago, American Indians harnessed the power of the earth. They used water from hot springs to cook with, bathe, and clean. Romans and Greeks had geothermally heated pools. Since then, humans have continued to improve their use of the earths natural heat, creating a source of renewable energy now known as geothermal energy.

Since its foundation, heat has been generated and radiated from Earth’s core. It is estimated that the center of Earth has a temperature similar to the surface of the sun, or 1000 degrees Fahrenheit. Through this heat, 42 million megawatts of power radiate from the core. This heat then rises throughout the layers of Earth to the surface.

Once four feet underground, the temperature of the Earth stays the same all year round, unaffected by weather, at approximately 55 degrees Fahrenheit. A Geothermal Heating System buries pipes at least four feet underground to reach this constant temperature. The system pumps a liquid through the pipes which absorbs the heat from the ground and brings it back indoors. The heat from the liquid is then used to heat the air inside homes.

Home Geothermal System

This is a small-scale Geothermal System for a home, but these systems can be large-scale geothermal power plants. These plants tap into hot water reservoirs underground and the heat is used to create electricity. The Geysers power plant in northern California is the world’s largest geothermal power plant, producing enough electricity to power more than 22,000 homes.

Geysers Power Plant

This brings up a concern however: if the power plants are tapping into underground reservoirs and using the steam to create electricity, won’t it eventually run out? The answer to this is no due to technological breakthroughs. Back when the Geysers power plant was initially opened in the 1970’s, vastly more steam was being produced than was being injected back into the reservoir. By 1989, accelerated steam use resulted in a lower steam pressure in the reservoir which meant lower steam production rates. In order to solve this problem at the Geyser plant and other geothermal operations around the world, a solution was put into place.

To sustain steam pressure rates, underground reservoirs need a large supply of water. The vast amount of heat in the reservoir rocks is unable to produce steam without water. To maintain optimal electricity production rates, water is injected into the underground reservoirs through pipeline. These pipelines run from various sources to the geothermal plant. Geysers receives its water from two sources: The city of Santa Rosa and Lake County. The 42-mile pipeline from Santa Rosa and the 40-mile pipeline from Lake County deliver 11 and 9 million gallons respectively of waste water per day to the Geysers Plant which replenishes the geothermal reservoir.

Currently in the United States there are 64 operating geothermal power plants currently having a power capacity of 3,187 megawatts. According to a recent panel led by the Massachusetts Institute of Technology, geothermal energy in the United States has the potential to reach 100,000 megawatts by 2060. This is the entire energy consumption for the country of France. With this promising statistic, geothermal seems to have great potential in the years to come. But should geothermal energy be pursued?

Pros:
1. Geothermal Energy is a renewable source of energy and as long as the Earth exists, geothermal energy will be available. This is roughly for another 4 to 5 billion years in Earth’s lifespan.
2. Geothermal Energy has the least environmental impact of any energy source. During the process of producing power, geothermal power plants produce virtually zero emissions. There is no carbon dioxide produced in the procedure and new technologies are allowing past sulfur emissions to be filtered.
3. With geothermal energy, there is an abundant supply that is being processed constantly. Unlike other renewable sources which depend on sunlight or wind, there are no shortages due to non-cooperating weather. The process is also extremely dependable and no fuel at all is needed during production.
4. Homeowner use of geothermal energy as a source to heat and cool offers significant savings and less energy usage. The Environmental Protection Agency states that homeowners save 30-70 percent of heating costs and 20-50 percent on cooling costs by using geothermal pumps. This translates to an average annual energy savings of 30 to 60 percent.

Cons:
1. Throughout the process, sulfur dioxide and silica are discharged into the air, water, and ground. Sulfur dioxide and silica can be a threat to human health, animal health, and plant life. Although in significantly lower concentrations than the burning of coal and oil, these compounds pose threats to planetary life.
2. Although geothermal energy is available for the remaining lifespan of Earth, only particular regions are suited for mass production. Prime geothermal energy zones are very specific and areas outside of these zones are virtually useless.
3. Geothermal energy on a homeowner scale requires a steep initial installation cost. For an average sized home, installation of a heat pump costs approximately $20,000. This initial figure can pay off itself in 5-10 years through significant energy cost savings.

I believe that geothermal energy should contribute to our energy usage in the time to come, but should not be the main source. Due to its virtually inexhaustible supply, geothermal energy offers a clean source of energy that can be a significant contributor to the world’s energy supply. Because it is only suitable to particular and limited areas on Earth however, I do not believe that geothermal will be the dominate source of energy in the future.