Geoexchange has become a general term applied to a number of similar types of heat exchange systems. Often involving a two way heat exchange, meaning that you store heat underground when you have excess energy and take heat from that same source when you require extra energy.

One example of this type of green technology is a system where heat is sent in to massive underground water tanks, to be stored until needed. For example, a large building has water solar panels gathering heat in the summer, the heated water is sent down in a closed loop pipe system to the underground tanks where the water in the pipes raise the temperature of the water in the tanks.

No Water Contamination

It is closed loop meaning that the water heated by the sun never leaves the piping system. It simply loops round and round from rooftop panels soaking up the suns energy. It is then pumped along the underground pipes, piped through the tanks, where the cooler tank water takes the heat energy from the water in the pipes. Slowly through the summer, the heat builds up in the tank water and the surrounding rock.

Water Going In To The Heating Systems Is Several Degrees Higher

Heating Boost In Colder Weather

Then in the winter months, the system can be reversed. The tank water then heats the piped water, which is then diverted to the heating systems. The result is that the water going in to the heating systems is several degrees higher than it otherwise would be and therefore requires less energy to bring it up to the required temperature for heating the building.

The heat going in to the underground system can also be boosted by heat pumps, which usually make excess heat in the summer.

To make this work, the tanks need to be big. A large volume retains more energy than a smaller smaller. A typical project like this may have tanks capable of holding over a million gallons of water, buried over 500 feet underground.

Return On The Investment Over, Let Us Say A 50 Year Period Is High.

Sound Investment

The upfront cost is high, but after installation, there can be considerable fuel bill savings, meaning that in a large building such as a hospital or school, the installation cost can be recouped after 10 or 15 years. Ongoing maintenance costs and the cost to run the electric water pumps are minimal compared to the savings. Therefore the return on the investment over, let us say a 50 year period is high. As always it also sounds like a good project in these times. In an educational facility it is inspirational and encouraging for scholars to be involved in or to learn about.

Helps Cooling In The Summer

Another advantage is that all the rooftop solar panels divert the heat away from the building in the summer, thereby reducing cooling costs.

About The Author
Richard Johnson
Chewells Contributor

Richard is one of our main oil industry contributors. He likes fast cars, motor boats and... »

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