Geothermal: The word “geothermal” comes from the Greek words “geo” meaning Earth, and “thermos” meaning hot or heat. So “geothermal” means “earth heat”.

Geothermal energy: The earth's core constantly stays at a very high temperature providing energy as heat from nature. This heat energy is named geothermal energy. The high temperature of the earth’s interior comes from three sources. The first is generated by the effect of the earth’s gravity, which pushes or pulls substances towards the earth’s core. This force grows stronger in areas closer to the core. Under the intense pressure, geocentric materials generate heat. Secondly, radioactive decay of minerals creates a massive amount of heat. Finally, the movement of the earth’s crust release huge amounts of energy, which further produces heat. This heat—geothermal energy—yields warmth and power that we can use without polluting or harming our environment.

Applications: In the earliest times, the use of geothermal energy was passive. For example, people have used geothermal water that flowed freely from the earth's surface as hot springs just for relaxing in the comfortable water. No additional technologies were available to transform geothermal energy into other types of energy. Later on, the Romans used geothermal water to treat eye and skin disease. As early as 10,000 years ago, Native Americans used water from hot springs for cooking and medicinal uses. And, since the 1960s, France has been heating up to 200,000 homes using geothermal water.

Nowadays, we drill wells into geothermal reservoirs to bring the hot water to the surface. Then, once the hot water and/or steam travels up the wells to the surface, it can be used to generate electricity in geothermal power plants or for energy-saving, non-electrical purposes. The geothermal plants do not burn fuel or generate smoke. There are three kinds of geothermal power plants.

1. “Dry” steam reservoir: the word “dry” indicates that this type of geothermal power plant produces steam but little water. The steam is conveyed through a rock catcher to “dry” steam power plants to provide the power to spin the turbine generator producing electricity. However, the “dry” steam fields are rare.
2. Hot water reservoir: a geothermal plant that produces mostly hot water with temperatures ranging from 300 to 700 degrees F. The water is pumped up to the surface by production wells. Because of the pressure in the deep reservoir, the water often flashes into steam upon its release. The steam then powers turbines to generate electricity.
3. "Binary" power plant: a reservoir with temperatures between 250 – 360 degrees F is not hot enough to flash adequate steam. Therefore, it is used to produce electricity in a "binary" power plant. In this system, geothermal water is passed through a heat exchanger and transformed into a binary liquid, which has lower boiling point. When heated, the liquid will turn to vapor and work just like steam, powering and spinning the turbines. Additionally, the system is a closed cycle in which the vapor can be re-condensed and reused without releasing harmful emissions into the environment. In the U.S., over 2800 megawatts of electricity is produced by geothermal power plants supplying 4 million people. In total, geothermal power plants are implemented in 21 countries globally. Data shows that 8200 megawatts of electricity is generated to support 60 million people in the world. Most of the 21 countries are developing countries.

Advantages: The number of direct applications (such as home heating), has been expanded due to recent technological advances and the many advantages offered by geothermal energy. Economically, geothermal energy is cost effective and it is not affected by the fluctuation of the price of oil. It protects domestic economies by avoiding importing. Geothermal power is environmentally friendly because it conserves fossil fuel. Geothermal wells do tend to release greenhouse gases trapped deep within the earth, but these emissions are much lower than those of conventional fossil fuels. It is also renewable and sustainable. As a result, geothermal power has the potential to help mitigate global warming if widely deployed and used to replace fossil fuels.