All About Geothermal Heating Systems and How They Save Energy

Learn how geothermal systems work to deliver earth’s ground-heat indoors and how they can serve as alternative cooling systems.


| April 2017



Refrigerator

Like a refrigerator, a geothermal heat pump simply transfers heat from one place to another. When a refrigerator is operating, heat is carried away from the inside food-storage area to the outside area—your kitchen. Cold is not being added; heat is being taken out.


Illustration courtesy PixyJack Press

With the outlook of the future environment in mind, our biggest priority is 100 percent energy efficiency or more. Geo Power (PixyJack Press, 2015), by Donal Blaise Lloyd, guides you through the elaborate geothermal process, that it takes to tap our earth’s free heat and put this sustainable option to work. Lloyd goes in depth to demystify the open or closed loop options to fit your unique location.

You can purchase this book from the MOTHER EARTH NEWS store: Geo Power.

If you dig down about five feet or so in the ground to below the frost level, you will find the ground temperature to be amazingly constant, 40 degrees to 70 degrees F (4–21 degrees C), depending on the location.

It is cooler than the air in the summer and warmer in the winter. The earth’s subsurface is an enormous heat sink — a solar battery — and it takes a large amount of energy to keep it in equilibrium. This heat energy comes in great part from the sun, a renewable and inexhaustible source of energy. In lesser amounts, it also comes from the center of the earth that we now know is a heat generator. The inner core of the earth is primarily made of a solid sphere of iron within a larger sphere of molten iron. Calculations show that the earth, originating from a molten state many billions of years ago, would have cooled and become completely solid without an energy input. It is now believed that the ultimate source of this energy is radioactive decay within the earth that continues to this day; the decay produces gradually diminishing temperatures from the earth’s center to the surface. This does not mean that dangerous radioactivity is a hazard to us. We can tap into all of this heat energy, transfer it into our home for heating and return that energy back to the earth during cooling: thus we are really borrowing heat from the earth.

Geothermal units use the same 100-year-old technology found in your refrigerator. They are both devices that move heat energy. It is worth noting that the refrigerator is the most reliable, longest-life appliance in your home. As the diagram in the slideshow explains, a refrigerator removes heat energy from food and moves it into your kitchen. A geothermal system removes heat energy from the earth to heat your home and in the summer removes heat energy from inside your home back to the earth.

Heat naturally flows “downhill” from the warmest medium to the coolest medium. A heat pump is a machine that causes heat energy to flow in the direction opposite from its natural tendency, or “uphill” in terms of temperature. Because work must be done (energy must be applied) to accomplish this, the name heat “pump” is used to describe the device.





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