We’ll cover the following topics for considering geothermal as a choice for your home.
Keeping your home comfortable in the summer and warm in the winter can cost a lot of money. In fact, heating and cooling your home is one of your biggest energy expenses. You can spend up to half of your energy bill on heating and cooling. So it’s important to consider your options in selecting the energy system that’s right for you.
You likely have many possible choices for heating and cooling your home. You could purchase electricity from your local utility company. That might power an in-home heater and an external air conditioner that’s connected as part of an HVAC system. You might instead choose to rely on oil, natural gas or propane for energy sources. These are often plentiful and cheap sources of energy, but they are fossil fuels that emit carbon dioxide. So they may not be the best choice. Instead, you might want to take advantage of renewable sources and use solar paneling, wind turbines or geothermal to create or harness energy for heating and cooling your home.
If you’re thinking seriously about renewable forms of energy, you’ll find that geothermal — specifically a geothermal heat pump — is perhaps the most versatile. You don’t have to be in a year-round sunny climate or situated between two mountain peaks. You just need a little space next to your home for an installer to place a geothermal heating and cooling system. The system will provide you with continuous temperature control, deriving energy out of the temperature differential between the air outside and the soil several feet under the ground.
In this article, you’ll learn how geothermal works and the types of geothermal energy. You’ll also learn about the advantages of geothermal that make it a great choice for your home.
First, let’s differentiate between geothermal energy and geothermal heating and cooling. Geothermal energy most properly pertains to the energy coming from deep inside the Earth. That energy sometimes manifests as a volcano, a geyser, or perhaps boiling mud or a hot springs mineral bath.
Although that form of geothermal energy can sometimes be harnessed for home use, it is only available at specific locations on the Earth’s surface. There are many of these locations in Japan, Iceland and throughout the Western USA. If you don’t live close to one of points where shallow geothermal sources can be tapped, then that form of geothermal energy is not directly available for you.
Although that energy is not directly available to you, you can still take advantage of it. By putting a larger energy system in place to harness that energy and transmit it to you over a distance, geothermal energy could provide an indirect source of energy for your home. For example, hot steam from below the ground can be used to spin a turbine, which in turn creates electricity. That electricity is then transmitted via the standard energy grid. Many locations across the globe offer the potential for tapping into deeper sources of geothermal energy, converting that energy into electricity, then delivering it to points far away.
But when most people talk about using geothermal for their home, what they mean is a system that can generate energy based on the differential between the outside air temperature and the temperature about four to six feet below ground. That’s a form of geothermal energy, and it’s usually called geothermal heating and cooling.
Technically, many engineers would say that this sort of energy isn’t really “geothermal” at all, because there’s no direct energy coming from a geyser or other heat source that can be converted to electricity. Systems that work on the heat differential between outside air and the temperature below ground are sometimes called “ground source heat pumps.” Sometimes you’ll see the term “geothermal heat pump” instead. These terms are more technical substitutes for the same general idea.
Geothermal (ground source heat pump) home units work because the temperature below ground remains mostly constant all the time. It varies between 50 to 55 degrees Fahrenheit. In many regions of the country, as the outside air temperature fluctuates between hot in the summer and cold in the winter, there is a temperature differential between that outside air and the core below ground. A geothermal heating and cooling system (also known as an HVAC system) transfers the extra heat from below ground into your home in the winter, and it transfers the extra heat from your home into the ground in the summer.
In summertime, a geothermal HVAC system will rely on a refrigerant to help cool a home. Some rely only on water. The refrigerant moves over a condenser, which cools the air in the condenser. This cooled air is then circulated in the home. The refrigerant is cycled back in the system via a compressor. The compressed refrigerant becomes hotter as it is under pressure. The refrigerant can heat to over 120 degrees Fahrenheit in this process.
The refrigerant is then cycled back to the ground, where the constant temperature below the surface cools it. The process then continues as the cooled refrigerant is forced back into the system above ground where it interacts with warmer air inside the home through the condenser — and the loop is complete.
In wintertime, a geothermal HVAC system works a bit in reverse. An indoor coil that was used for cooling in summer now functions as a condenser, heating up the outside air. The refrigerant being driven through the system is warmed up under pressure. This heated refrigerant turns into a gas and is then moved over coils while a fan blows the heated air into your home.
The refrigerant leaves the coils and turns from a hot gas to a cooler liquid. It passes through an expansion valve, which is a bit like a dam that only lets a bit of the refrigerant through at a time. This greatly reduces the pressure on the back side of the valve, which in turn quickly cools the refrigerant (to as cool as 20 degrees Fahrenheit). From there, the refrigerant heads back to the ground to warm up, turn back into a gas and start the process all over again.
You may be surprised to learn that people have been using geothermal energy for a really long time. As far back as 10,000 years ago, American Indians relied on hot springs for heat, as well as for cleaning.
In the early 1900s, people started using geothermal as an energy source that could be converted into electricity. By 1960, an 11-megawatt (MW) geothermal power plant operated by Pacific Gas and Electric was delivering electrical power to hundreds of thousands of people.
With regard to using the heat differential between the air and ground, there were some early ideas about this in the mid-1800s and early 1900s, but it wasn’t put into practice until around the end of World War II. Professor Carl Nielsen of the Ohio State University is credited with the first successful residential implementation in 1948.
Today, there are more than one million geothermal heat pumps providing HVAC services around the world. The annual rate of increase for the use of geothermal heat pumps is 10 percent, and that’s come mostly from the USA and Japan.
Geothermal energy has many advantages. When talking about geothermal from geysers and other underground sources, the energy is renewable and can be harnessed on a large scale. But let’s focus on the advantages of geothermal heat pumps for your home. When you install a geothermal heat pump in your home, you benefit from a heat and cooling source that is:
The main disadvantage of relying on a geothermal heat pump is the initial cost. While the cost varies by the size of installation and the location of the installation, some estimates indicate that the cost of a new system will be recouped in about four to 15 years, depending on what you would be paying your utility company for comparable energy use.
Another disadvantage is that a geothermal heat pump system is not something you can install yourself. There’s a lot of significant engineering work that goes into the installation. That’s why you need to call on an expert to do the job for you.
Geothermal energy systems are often misunderstood. But once you do understand how the systems function, the advantages of geothermal become very evident. This is particularly true for residential geothermal energy.
There are several different engineering designs that can be constructed to provide a geothermal heat pump system for your home. They all work as described above, but the placement of the cooling loops underground can vary. The right design depends on the layout of your home and property. There are typically three types of installation for geothermal energy systems: horizontal, vertical and under a lake or pond.
A horizontal installation is typically less expensive than a vertical installation. If you have a lot of land around your home, a horizontal installation is likely most appropriate. The trenches for the cooling loops will need to be at least four feet underground. They’ll take up some space, which is fine if you have the space.
If, on the other hand, you have limited available land, a vertical installation is better. Instead of laying cooling loops in trenches, the loops extend down vertical holes dug into the ground. While this is a more expensive installation, it’s sometimes necessary when there isn’t enough room for horizontal trenches.
Another possibility is to run the cooling loops through a nearby pond or lake. Pond or lake cooling is typically less expensive than horizontal or vertical layouts in the ground, so this is an important alternative to consider if it’s available. The loops have to be sunk at least eight feet under the surface of the water in order to ensure they won’t freeze in the winter.
The interest in using geothermal systems for heating and cooling residential properties continues to increase, and with good reason. Geothermal systems can provide reliable heat in the winter and air conditioning in the summer. They do so with very little noise, requiring few and infrequent repairs and at a very low cost once a system is installed. With geothermal energy, you can feel good that you have a virtually pollution-free energy system that can last multiple generations at your home.
At Shipley Energy, we use our energy and services expertise to make a positive impact on your everyday life, and the community you call home. We are committed to making energy easy through friendly service and innovative solutions. Whether in your home or business, we create a path to consumer empowerment through a wide-range of energy plans, and service options, alongside educational resources that help you make informed decisions that work best for your energy needs and budget.