I've written quite a few articles for Green Living Tips on renewable energy systems; primarily solar power, solar hot water and wind energy.

A form of renewable energy I've pretty much skipped over that a few GLT readers are using in their homes is geothermal energy; in the form of geothermal heat pumps, also known as ground source heat pumps. The feedback I've had from readers writing to me about their systems has been very positive.

So, what is a geothermal heat pump and how does it work?

Steve Ewings has published a book on geothermal heat pumps and provided me with the following brief explanation:

"When people hear the word ‘geothermal’ they often think of hot magma deep underground, venting volcanic geysers or hot springs. However in the context of a Geothermal Heat Pump (GHP) or ground source heat pump (GSHP) as they are sometimes known, the geothermal simply refers to the temperature of the ground below the Earth’s surface.

To explain this better, and if you were to climb deep into a cave on a cold winter day, you would immediately notice the temperature in the cave is a good deal warmer than the ambient air temperature. Conversely, if you went into the cave on a scorching summer day, the temperature in the cave would be a great deal cooler. In fact, the temperature in the cave would be the same in the summer, as it was in the winter. That is because the temperature of the earth several feet below the surface is constant throughout the year.

A Geothermal Heat Pump system uses underground pipes to transfer heat from the warmer earth to your home in the winter, and takes the heat from your home in the summer and discharges it into the cooler ground. So you can see that ground source heat pumps do not create heat; they move it from one area to another. Very clever!

However, the real genius of the system is one system can be used both heating and cooling, practically eliminating the need for separate furnace and air-conditioning systems. So in the summer months your water will be heated by the excess heat taken from your home during the cooling cycling which provides virtually free hot water. A ground source heat pump system can shave anywhere between 50-75% off your home heating and cooling costs, which represents a huge saving over the life of your home."

A ground source heat pump is a big investment, so be sure to do your research. If you'd like to learn more about geothermal heat pumps, check out Steve's book, which can be purchased and downloaded online.

Are you using a ground source heat pump? Share your experiences below! Have questions? Ask them below also and I'll ask Steve to drop by and answer them!