What is Geothermal Energy? Definition and Uses

One of the greatest challenges of our era is to produce sufficient energy to power our cities and economies while minimizing negative impacts on the environment. At the moment, fossil fuels (coal, natural gas, and oil) cover energy demand, and they will continue to do so well into the first half of the 21st century, but as deposits will become depleted and environmental constraints tighten, the need use of renewable energy resources will become imperative. What is geothermal energy?

Solar and wind energy are already advancing at a rapid place while geothermal energy and tidal power are starting to gain ground. After years of stressing the potential of geothermal energy production and the environmental virtues of baseload renewable energy, the U.S. government is finally ready to embrace a new form of power: geothermal.

Out of all energy forms we consider geothermal the most sustainable and reliable one, with proven applications that date back to the earliest times in human history. In the last decades, the technology used in the harnessing and conversion of geothermal energy has improved dramatically, but many home-owners have yet to implement it because they are ill-informed, or worse, completely oblivious.

To ensure that geothermal energy usage increases over time, we will try to answer the most important questions regarding this renewable energy form like: “What is geothermal energy?”, “What does geothermal energy mean?”, “What is geothermal energy used for?”, “What countries use geothermal energy?”, “What is the source of geothermal energy?” etc.

The basics of geothermal


The Basics: What is Geothermal Energy?

Geothermal power can be defined simply as the heat energy that emanates from the Earth’s core. Geothermal resources are rich in thermal energy trapped within rock, steam or liquid. Because the Earth’s core has a temperature of roughly 7.000 K and pressures that exceed 360GPA, it is safe to say that geothermal power has huge potential.

Furthermore, as opposed to wind and solar power, climate change has little to no impact on the effect of geothermal energy (this is also the reason why it is considered a baseload resource), but correctly harnessing and converting geothermal resources into energy could reduce greenhouse gas emissions and mitigate climate change.

Geothermal energy has been defined by several online publications. Here are a few definitions that will help you better understand the concept.

“Geothermal energy is energy derived from the heat of the earth (…) Heat from the centre of the earth conducts outwards and heats up the outer layers of rock called the mantle. When this type of rock melts and becomes molten it is called magma. Magma can reach just below the earth’s surface.” Source: TechnologyStudent

“Geothermal power is a form of energy obtained from within the earth, originating at its core, also, energy produced by extracting earth’s internal heat.” Source: Dictionary Reference

“Geo means <from the earth> and thermal means <heat>, so this type of energy is found under the earth.” Source: The answer to ‘What is geothermal energy?” as given by Alliant Energy Kids

How Geothermal Energy Works

In order to truly understand the benefits of using geothermal energy as an alternative to fossil fuels, we must familiarize ourselves with the basic workings of this technology. So what does geothermal energy do, and what is the source of geothermal energy?

This fascinating renewable energy source has its origin in radioactive decay and various minerals that formed over millions of years. Many people believe that geothermal energy can only be found in geysers, fumaroles, hot springs and volcanoes, but this represents only energy that comes in contact with the Earth’s surface. The largest reserves of G.E. cannot be seen, but they lie untapped under the surface of the earth.

Our planet is a hotbed of geothermal power. This means that, as long as the Earth exists, nearly any location on the globe will benefit from its direct or indirect applications. The regions with the biggest potential for geothermal energy are situated around the Ring of Fire in the earthquake-prone region of the Pacific Ocean. Here you can find hundreds of high-temperature geothermal systems associated with volcanoes.

It is very important to understand that geothermal energy isn’t made, it’s moved. The purpose of G.E. technologies is to tap into the power that already exists below the earth’s surface and to move it through a system of pipes to provide direct heat or to be converted into electricity.

what is geothermal energy

Geothermal Energy Diagram

Here’s how geothermal for homes happens:

  • In the ground, a 1-inch high-density polyethylene closed loop pipe system filled with water circulates heat between the earth and the house. In most cases, pipes descent into vertical wells before ganging together in a header that brings warm water to the basement’s walls. Thermal conductivity is enhanced with the help of bentonite grout.
  • In the house, water is cycled through the pipes with the help of pumps until it reaches the heart of the system: a geothermal unit that acts as air conditioner and furnace. Heated air is then circulated through the house with standard ductwork and a device called

Recommended Read: The Guide to Home Geothermal Energy

What is Geothermal Energy Used for?

1. Geothermal Electricity Generation

Most industrial power plants require steam, which rotates a turbine, to generate electricity. At present, more than 50% of power plants use fossil fuels to boil water for steam, but geothermal power plants can change this because they use steam directly from the ground and hot water reservoirs. For the production process to be successful, however, the water temperatures must exceed 360 degrees Fahrenheit.

There are three basic types of geothermal power plants: dry steam, flash steam, and binary cycle.

  • Dry steam power plants extract geothermal steam resources from the ground and direct them through pipes from the well to the power plant’s turbine or generator. There are currently two underground resources of steam in the U.S. – Yellowstone National Park (protected from development) in Wyoming and The Geysers in northern California.
  • Flash steam power plants are extremely wide-spread. They tap into the power of underground hot water reservoirs. Again, pipes are used to force hot water through wells, upward. As the pressure decreases, a percentage of water boils and turns into steam. This steam is then separated from the water (which is recycled) and used to power the turbine/generator.
  • Binary cycle power plants are similar to flash steam power plants. Their greatest advantage is that they work with lower temperatures (approx. 225-360 degrees Fahrenheit). This type of plant uses heat from hot water to boil a working fluid (waste water or organic compound). As the working fluid vaporizes, it generates steam, which powers the turbine/generator.

Examples of Geothermal Energy Power Plants

Dixie Valley Power Plant

  • Dixie Valley Power Plant, Nevada: This geothermal plant is located along a range front fault that runs from the north-western edge of the Dixie Valley to the Stillwater range. It is also the hottest known deep-circulation system in the Basin.
  • Geothermal Well Drilled at Coso: The thermal features of China Lake have been long known, but because the Coso Hot Springs is considered sacred land to the Paiute and Shoshone tribes, activity in the area started late. The first production well was successfully completed in 1981.
  • The Geysers Geothermal Field, California is located 115 kilometers north of San Francisco, in the Mayacamas Mountains. It has an installed capacity of 1,517MW thanks to its 22 geothermal plants.
  • Palinpinon Geothermal Power Plant. Situated in the Valencia, Philippines, the Palinpinon G.E. plant –founded in 1983- operates as a subsidiary of National Power Corporation.

The Geysers, Santa Rosa

Full List of Geothermal Power Stations: Wikipedia

2. Geothermal Direct Heating

One of the uses of geothermal energy technologies is to enable the houses, buildings and facilities to heat themselves. Steam flows through underground pipes and into walls and floors of buildings to increase the temperature. The best thing about this form of direct heating is that it doesn’t use any fossil fuels.

3. Geothermal Heating in Residential Cooling

The same concept, only reversed, is used to cool homes and small structures for summer. Geothermal cooling technologies take heat from the house and send it down pipes, in underground reservoirs (where it naturally cools). The air is then returned to the home, in order to regulate temperature. For this technology to work, G.E. systems must use liquid like antifreeze that is moved through a closed-loop pipping system.

Geothermal Energy in Farming

Geothermal energy is also used to heat greenhouses during summer. Farmers have been using G.E. to grow vegetables in the cold season for hundreds of years. This technology is also being used in fish farms.

Geothermal Energy Use in Infrastructure

As geothermal technologies are advancing, new and innovative applications are found for this form of energy. In various countries, for example, geothermal power is used to heat sidewalks and roads during winter. The Netherlands uses geothermal energy to keep bike lanes from freezing.

geothermal energy for unfreezing sidewalks

Recommended Resources:

Now that we have answered “What is geothermal energy” and other important questions that cover the basics of G.E., it’s time to take a closer look at the pros and cons of geothermal energy, and detailed information about energy efficiency and the science behind specific G.E. technologies. Stay tuned for more news on geothermal power!

Image Sources: 1, 2, 3, 4, 5

Write a comment