Geothermal Heating and Cooling/Ground source Heat Pumps

From Wikibooks, open books for an open world
Jump to navigation Jump to search

Ground Source Heat Pumps

A Ground Source Heat Pump is a heating/cooling system based on a heat pump that gets its source from the ground. There are many different techniques that can be used to extract heat from the ground, but the safest one ecologically speaking is the closed loop type.

Despite this, many people who pioneered this type of heating, experimented and continue to experiment with alternate techniques that are not as expensive, or are more ecologically or legally sensitive. One such technique called Open Loop Geothermal, has been recommended against due to its potential for cross contamination of water sheds. Others such as deep lake geothermal have been recommended against for the damage they might do to fish habitat.

The main reason that closed loop geothermal is not recommended against is that the contaminants tend to stay within the system, at least until the system breaks down some 70 years in the future. By judicious choice of antifreeze, it should be possible to keep contamination down to an ecologically sound level even at that time. Further the installation lies under the surface of the ground where there is less chance of an accidental broaching of the system.

A Ground Source Heat Pump consists of a number of different loops that work together to produce the effect of geothermal heating or cooling. The Ground Loop brings the temperature of the ground into the building, using nothing much more complex than pipes in the ground, filled with a water antifreeze mix. The refrigeration coils transfer heat between the ground loop and the air loop, and the air loop transfers heat between the refrigeration loops and the building's air.

The secret that makes this system work, is the heat pump which is a large refrigeration unit that can often pump heat both ways. The system works quite simply by pumping heat out of the ground, and into the building, thus heating the building, or pumping heat out of the building and storing it in the ground thus cooling the building. The reason that this is possible and cost effective, is simply that the ground is heated every day by the sun, and so we are not creating heat so much as pumping it from place to place, which is much less expensive.

Modern two stage scroll compressors, are capable of being installed into Geothermal systems that produce 320% more heat than they consume power. In places where refrigeration and heating are both involved efficiencies have been reported up to 700% of the power it takes to run the system.

However the more complex the system involved the larger the up-front cost, extending the pay back period for a particular installation.