Geothermal enrgy systems utilize an alternative energy source, by taking advantage of the near constant temperatures of soil, groundwater, or aquifers. These temperatures range from approximately 45 to 60 degF (8 to 15 degC), depending on where you live and on how deep the piping is installed. These systems are called geothermal or ground source heat pumps.
Geothermal energy systems use heat pumps to either draw heat from the earth during the heating season and for domestic hot water, or reject heat from the home into the earth during the cooling season.
Most often the systems are so called closed loop systems, in which the water or water/glycol mixture is circulated through the ground and into the heat exchanger in your home in a closed, sealed loop.
Some applications use open loop systems where water is extracted from the ground, a pond or lake and circulated through the home. It is then discharged back into the ground, pond or lake. This option, for me, raises concerns about heating up ponds and lakes during the cooling season to a level where these higher temperatures will have a negative impact on animals and plants. This option is, in my opinion, not recommended and is only mentioned here for completeness.
A geothermal energy system consists of the following components:
- Piping
- Heat Pump
- Water Circulating Pump
Piping is buried in the ground outside your home. As water circulates in these pipes it will heat up or cool down to the temperature of the surrounding earth, groundwater or aquifer.
The pipe is installed either horizontally in trenches, vertically in bore holes or looped through a nearby pond or lake. Your geographical location, the consistency of the soil and your specific needs will determine the type of layout. For example, most systems in New England are of the vertical type, because there is insufficient top soil to bury the pipes in.
In an oil-fired system the water circulates through a boiler and then to water heater or the home heating loop. In a geothermal heatpump system, the water circulates through the earth and through the heatpump, instead of through the boiler. Hot water from the ground source heatpump is then piped through heat exchangers to heat the domestic hot water and/or to supply heating hot water to floor heat or radiators.
Geothermal, or ground source heat pumps essentially are go-betweens between the water, which circulates through the ground, and the water or air, which circulates through your home. Heat pumps function very much like a refrigerator, which draws the heat out of the inside of the fridge/freezer (the earth) and rejects it into the kitchen (your home).
During the cooling season, heat is rejected to the ground by the heatpump. Inside your home, the AC system works just like any other AC system.The geothermal heat pump will operate in reverse and extract heat from your house, during the summer, if your home requires air-conditioning. This capability to reverse the direction of heat flow, is a big advantage of heat pumps, because the same piece of equipment can be used for heating and cooling.
Here is an example of a residential geothermal heat pump, used for heating and cooling. It doesn’t look much different than a regular AC unit, does it?
Credit: John Barlean – Northwest Public Power District
Heating with a geothermal energy system requires that the home be very well insulated, air tight and have low heating and cooling loads. Geothermal heat pumps provide hot water temperatures of max 130 degF. (55 degC), which is ideal for floor heat, and too low for standard heating systems. The lower temperatures of the heating system reduce the energy requirements and increase the comfort of the home owners. Poorly insulated and leaky homes require large (and expensive) systems.
Pumps installed in the home are used to circulate the water through the buried piping and to distribute the heated, or cooled water through the heating system, the air conditioning unit, or the domestic hot water tank, just like with a standard system.
A solar photovoltaic or wind power system can be utilized to produce the required electrical power for the heat pump, any circulating pumps or the fans in the air conditioner. This combination might allow you to completely heat and cool your home with alternative energies.
Watch this short video, which will give you a nice overview on geothermal energy systems:
Geothermal Heating & Cooling System
Here are three other good write-ups on geothermal heatpumps.
Consider Geothermal For Your New Home Heating System! – If you are considering replacing your heating and cooling systems or if you are building a new home then you should consider the advantages of using geothermal! One of the most energy efficient methods of heating and cooling your home …
Geothermal Energy Facts: Geothermal Energy Pros and Cons (Chris … – There is much talk about climate change, and the search for viable renewable energy sources. Everyone knows about the likes of solar, wind and wave power. But fewer have heard of geothermal, or know how does geothermal energy work.
Ask Plenty: Installing geothermal – A. Before we tell you how to get started on geothermal, Lisa, answer us this: what do George Dubya and Ani DiFranco have in common? GEOTHERMAL. No lie, they both tap into earth’s stable core temperature in order to heat and cool their …
Read more about other alternative energies and general information about building a green home:
