Heating and Cooling with Geothermal Heat Pumps

What is Thermal Energy? See How it Works

Geothermal energy comes from heat that is stored in the earth’s core. The Earth’s core is extremely hot, as can be seen from things like volcanoes, hot springs, and geysers. Although we don’t have volcanoes or hot springs here in Michigan, the temperature remains a constant 50-55 degrees or so just a few feet under the ground, even during winter.  A geothermal furnace heats your home by utilizing this constant energy source.  See the diagrams below to learn more about how geothermal energy works:


The diagram above shows a geothermal system utilizing a horizontal loop.  Water circulates through this system, absorbs heat from the ground, and returns it to the geothermal heat exchanger.

 
The diagram above shows a geothermal system using a pond loop.  Instead of having the pipes contact the ground directly, they loop through a body of water which exchanges energy (heat) with the earth.


The diagram above shows a vertical loop design for geothermal heating and cooling.  Arranging the loop system vertically is a good solution for situations with limited space.


The diagram above shows an open loop geothermal design.  A supply of ground-temperature well water provides geothermal heat before flowing back into a pond or other body of water.

Geothermal Energy pros and cons

Pro: Geothermal energy is renewable and sustainable. This means that geothermal energy is replenished naturally, and it won’t run out within the foreseeable future.
Pro: Geothermal energy is a clean, environmentally friendly energy source.
Pro: Geothermal heating and cooling systems are exceptionally efficient, often saving up to 80% on home heating and cooling bills.
Con: The up-front cost of installing a geothermal system typically costs more than a conventional heating and cooling system.
Con: Installation options may be limited based on lot features. For instance, a horizontal geothermal loop system that requires a wide area may not be an option for a home that is built on a city lot.  If you really want it, though, there is often another geothermal design (such as a vertical loop) that may still be an option.

Geothermal Energy Facts

When your home needs to be heated, earth-temperature water is drawn into the geothermal furnace and the heat is compressed to a higher temperature. In a typical closed loop system, the water would then circulate back through the loop system and absorb more heat from the earth. In Michigan, geothermal energy can be used not just for heating, but also for cooling since the temperature of the earth is warmer than the air during winter but colder than the air during summer. The flow and temperature compression are simply reversed during each season to heat or cool your home. There are several different configurations for a geothermal heating and cooling system. Horizontal and vertical loops systems use a series of water-filled pipes that absorb heat from or dissipate it into the surrounding earth. Open loops can use a supply of well water, and pond loops have a pipe system in a lake or pond that the water circulates through.