Geothermal Energy @ Home: The Next Hot Thing?

geothermal canva house

Image Generated by Canva


When people think of renewable energy, they may include geothermal energy in the mix. But rarely do they consider the possibility of geothermal energy for their home. Recent research indicates it is possible for individual buildings to have their own geothermal energy source, even in the Midwest. How does this work? Does this mean you need to have a geyser in your yard? How does this support conservation? We’ll discuss these matters in this blog.


What is geothermal energy?

Geothermal energy is heat energy from the earth. It is considered renewable, reliable, and clean. Geothermal energy is visible on the surface as volcanoes, geysers, or hot springs. Some applications of geothermal energy use the earth’s temperatures near the surface and others require drilling miles into the earth. The United States Energy Information Agency (see insert about EIA) defines three main types of geothermal energy systems: direct use and district heating systems, geothermal power plants, and geothermal heat pumps.


Direct use and district heating systems
EIA informationDirect use and district heating systems use hot water from springs or reservoirs located near the earth’s surface. Ancient Roman, Chinese, and Native American cultures used hot mineral springs for bathing, cooking, and heating. Today, many hot springs are still used for bathing, and many people believe the hot, mineral-rich waters have health benefits. I have been fortunate enough to enjoy soaking in hot springs and consider that a nice twist on NatureRx.


Geothermal energy is also used to directly heat individual buildings and to heat multiple buildings with district heating systems. Hot water near the earth’s surface is piped into buildings for heat. A district heating system provides heat for most of the buildings in Reykjavik, Iceland. Based on my travel to Iceland, I can vouch that the geothermal heating used for hotel towels worked really well.


Geothermal power plants for electricity generation
Geothermal electricity generation requires water or steam at high temperatures (300°F to 700°F). Geothermal power plants are generally built where geothermal reservoirs are located, within a mile or two of the earth’s surface.


Geothermal heat pumps
Geothermal heat pumps use the constant temperatures near the surface of the earth to heat and cool buildings. Geothermal heat pumps transfer heat from the ground (or water) into buildings during the winter and reverse the process in the summer. A geothermal heat pump circulates water through pipes buried in the ground, or submerged in a water body, to heat and cool a building’s HVAC system. This type is being considered for homes and other individual facilities.


What are the challenges and opportunities?

EnergySage has done a nice job of summarizing the pros and cons of geothermal energy. On the pro side, geothermal energy is a reliable source of power that has a small land footprint compared to other renewable sources; it can be harnessed at both large and small scales, the industry is expanding, and its infrastructure is long-lasting. On the con side, geothermal power plants can only be built in certain locations, they are often expensive to build at first, and can cause surface instability and earthquakes.


geothermal energy pros and cons chart

Source: EnergySage


Geothermal heat pumps for the home potentially address the cons as they can be done for an individual facility regardless of the location. They are too small to lead to any meaningful surface instability. And despite high initial costs, many feel that they can be justified financially from reduced monthly energy bills.


heat pumpsFor instance, the University of Illinois at Urbana-Champaign has been spearheading the use of geothermal heat pumps around its campus. An example of one of its completed projects is the use of geothermal heat pumps for the Evergreen Lodge of Allerton Park which resulted in significantly reduced kilowatt-hours usage. The picture on the right (courtesy of the University of Illinois) shows the surface view of the heat pumps. Notice no geysers?


According to the U.S. Environmental Protection Agency (EPA), geothermal heat pumps are the most energy-efficient, environmentally clean, and cost-effective systems for heating and cooling buildings. All types of buildings, including homes, office buildings, schools, and hospitals, can use geothermal heat pumps.


And yet, upfront costs are still a challenge for geothermal heat pumps. Nathan Van Zuidam, an architect now at INFORM Studio, has been involved with the design of numerous libraries and other buildings. He told me, “Due to its sustainable qualities and high efficiency, it is common for geothermal systems to be proposed early on in the design. Unfortunately, tight construction budgets often result in these systems being removed from the scope of the project.”


But as technology progresses, the financial benefits are becoming tangible. In fact, the Geothermal Alliance of Illinois says this about the financial benefits of home geothermal systems: “A single piece of equipment has the ability to heat and cool your home, while providing some or all of your home’s hot water as well. Geothermal systems can save you 30 percent to 70 percent on your monthly utility bills.” They believe this will work for newly constructed homes as well as for retrofitted systems in existing homes.


How does a geothermal heat pump work?

Geothermal Heat Pumps (GHPs) take advantage of constant underground temperatures to efficiently exchange temperatures, heating homes in the winter and cooling homes in the summer. Although air temperatures above ground change throughout the day and with the seasons, temperatures of the earth 10 feet below ground are consistently between 50°F and 60°F. For most areas of the United States, this means soil temperatures are usually warmer than the air in winter and cooler than the air in summer. Geothermal heat pumps use the earth’s constant temperature to heat and cool buildings. Geothermal heat pumps transfer heat from the ground (or water) into buildings during the winter and reverse the process in the summer. A geothermal system circulates a water-based solution through a buried loop system to take advantage of these constant temperatures.


A type of geothermal heat pump system

Source: U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy


Considered the heart of the system, there are many types of loops: closed loops, vertical loops, horizontal loops, pond loops, and open loops. For further details, go to the Geothermal Alliances of Illinois About Geothermal webpage.


What does this mean for conservation?

The use of geothermal energy and conservation are different means of achieving common goals for addressing climate change. Conservation organizations can augment current electricity sources with geothermal heat pumps for power, heating, and cooling of buildings and other facilities. And there would not be any geysers spouting high temperature steam! I suppose there could be some nice decorations on the ground above the pump. The Conservation Foundation has already installed solar panels at both of its farms/offices in Naperville and Montgomery, and has a small wind turbine at the McDonald Farm. Finally, conservation organizations can promote the use of geothermal energy at home and beyond to help with air pollution, reduction of emissions, and climate change.


Ready to support conservation and a sustainable future? Well, that is what The Conservation Foundation does every day. We can all do more together than we can alone. Join our collective momentum – become a member today!


Feel free to comment on this blog with additional ideas you have on geothermal energy and conservation.


By Steve Stawarz, Oak Brook
DuPage County Advisory Council Member


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