Geothermal 101: Frequently Asked Questions Regarding Geothermal Energy


As the world of renewable energy expands, geothermal energy becomes more popular. Though lesser known than solar and wind energy, geothermal energy technologies increase the potential to lessen fossil fuels and greenhouse gas emissions in our world. As of 2019, seven states in the U.S. have geothermal facilities that account for 0.4% of energy generation. It is currently used in over 20 countries. The United States is the largest geothermal energy producer in the world, with the largest geothermal field being The Geysers in San Francisco, California.


So, what should you know?


What is geothermal energy?

Geothermal energy is derived from the heat in the sub-surface of our earth, coming from hot water reservoirs and molten rock beneath the surface. It is considered a renewable energy source because it is continuously produced and can be utilized without depleting the resource. As a clean energy form, it can be used to heat and cool buildings and to generate electricity. However, to be used for electricity, it’s important to be close to tectonically active regions where the potential for geothermal energy is high. This is where geothermal power plants are located.

There are three types of geothermal power plants:

  1. Dry steam – this type of plant takes steam out of the ground and drives it directly into a turbine. It’s the oldest form of geothermal technology.
  2. Flash – this type of plant takes deep, high-pressure hot water beneath the surface and converts it into cooler, low-pressure water.
  3. Binary – this type of plant takes hot water that is passed through a secondary fluid with a much lower boiling point, allowing the secondary fluid to turn into vapor that then drives a turbine. According to National Geographic, this type of geothermal power plant will be the most popular in the future.


How does geothermal energy work?

To access this energy from the sub-surface for electricity generation, mile-long wells are dug into these underground reservoirs in order to access the hot water and steam. This then drives turbines that connect to electricity generators located in geothermal power plants. 

A geothermal heat pump system can be used to extract heat to heat homes in the winter, and then transfer that heat back into the ground during the summer. Some U.S. cities even have pipes of geothermal hot water beneath roads and sidewalks to melt snow.


How can it be used in your home?

You don’t actually have to live near geysers to take advantage of geothermal energy, that’s just where power plants are located. Even if you aren’t in an area with geothermal power plants, you can still utilize geothermal energy to heat and cool your home. 

Geothermal energy can provide your home with heating, cooling, and hot water through a geothermal HVAC system by taking advantage of the temperature of the ground. This system both collects energy to heat your home, and pulls it from your home to be released it into the ground, which cools your home. There are two types of HVAC systems available:

  1. Open loop system – this type of installed system takes water from a pond, lake, or water well and uses it to heat or cool your home through a heat pipe. This is less common than a closed loop system because it interacts with fluids outside of your home.
  2. Closed loop system – this type of installed system has pipes with a water solution buried underneath your home. The water or solution within the pipe changes temperature as the seasons change, so the system uses a heat pipe to warm the air in your home and vice versa. They are called “closed loop” systems because they only function for your home and don’t connect to a larger infrastructure. 

There are several benefits to installing a geothermal HVAC unit for your home. The on-going cost is lower than that of other HVAC systems that utilize non-renewable energy, it operates quieter than other systems, it has a longer lifespan, and it requires less maintenance than other systems. It feels like a regular AC and heating system, but the energy is clean.


How much does it cost?

Prices of the average geothermal system vary depending on the size of your home and the climate of your area. The estimated price of a system can range from $18,000 to $30,000 depending on the size of your home, but there are federal and state incentives that can help significantly reduce the price. As of 2021, you can claim a 26% federal tax credit on your income taxes after purchasing and installing a geothermal system. It’s also extremely cost efficient–you will see a 20-50% savings on your monthly utility bill with a geothermal system! 


How does geothermal energy affect the environment?

Flash geothermal power plants emit excess steam. However, binary geothermal plants have no emissions or liquid discharge; the U.S. Department of Energy’s Office of Energy Efficiency & Renewable Energy believes binary geothermal plants will be the dominant technology in the future compared to the other types of geothermal power plants.

The salts and minerals within the geothermal fluids that binary geothermal plants discharge are recycled back into the reservoirs for reuse. Some plants also produce solid materials that require disposal, but the chemicals are often extracted and resold for use, making it more environmentally friendly.

When it comes to geothermal HVAC systems you can install for your home, there are no emissions or negative impacts to the earth, unlike the typical non-geothermal HVAC system. Typical non-geothermal HVAC systems that most people use today use a refrigerant that harms the ozone layer. You can avoid this by installing a geothermal HVAC system that does not negatively affect the environment!


What is the reality of geothermal energy?

Geothermal energy has been around for years, but the common misconceptions have led some people to avoid it. Geothermal energy systems operate at 400-600% efficiency as opposed to 96% efficiency for the highest performance fossil fuel furnaces (most are between 80% and 90% efficient). And though they may seem more expensive initially, the long-term savings make up for that initial investment. 

Most average consumers can utilize geothermal HVAC systems for heating and cooling needs, but when it comes to geothermal power plants, only those in the surrounding geographical area can utilize the electricity produced. Just like other power plants, geothermal power plants are usually connected to the grid–and more effort is underway to install transmission lines so that these power plants, and other renewable energy power plants, can be used on a larger scale. This makes it hard for homes worldwide to only function on geothermal energy, but the use of these systems to heat and cool your home would still significantly help you and the environment.



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