Eighty percent of energy consumed in the United States comes from fossil fuels (USA Facts,2020). This energy is used for a wide range of purposes, such as the following:TransportationHeating and cooling buildingsIndustrial processesHousehold needs (e.g., cooking and laundering clothes)However, fossil fuels are limited in supply, damage the environment when mined, producegreenhouse gases, and emit air pollutants when used. How can these problems be solved? Oneapproach is to harness alternative sources of energy that are readily available, are cost-effective,and do not cause pollution.Renewable energymeans that a power source can be regeneratedor that energy has a limitless source (e.g., the sun).Renewable energy sources have no shortage because they are self-replenishing and can be usedrepeatedly. Some sources of renewable energy are the following:SunWindWaterBiomassGeothermal heatAlthough these sources do not cause the environmental damage that is associated with miningand burning fossil fuels, they can still have an impact on the environment. The major differencebetween renewable and nonrenewable energy is that renewable energy is environmentallysustainable, whereas the latter is not.What is geothermal energy?Worldwide, springs yield hot, almost boiling, water. These areas, such as the hot springs inYellowstone National Park, also have natural steam vents and other thermal features. Thesefeatures occur where the hot molten rock of Earth's interior is close enough to heatgroundwater. In many places, these features are also located near volcanic regions (Wright &Boorse, 2017).Geothermal energyis heat energy that is extracted from the earth. If you were to dig deep intoEarth's surface, you would find that the deeper you get, the hotter it is. For every 100 metersthat you dig underneath the ground, the temperature increases by approximately 3°. This isbecause Earth's core consists of a solid ball of hot nickel and iron that is 5,000–6,000 °C.(National Geographic, 2020a) You can observe this phenomenon when geothermal energy isreleased aboveground through geysers and hot springs and during volcano eruptions.
