Geotherm – the renewable Energy from the Ground:

Geothermal energy – also called earth heat – is in the form of heat stored energy below the surface of the earth. This natural Ground source can be used for heating purposes and also for electricity production.

The different ways of geothermal power production, distinguished them between the depths they work at. Some work close to the surfaces at approx. 400-m depth and some go even deeper (Deepherme).
In the Geotherm area of the surface where the temperature level is approx. – 25°C the application of a heat pump is necessary, one is usually sufficient to reach the desired temperature level.

These days, house-owners are confronted with steadily rising energy costs, looking for suitable ways to get out. This is how the heat pumps also came into the picture.
Advertising messages suggest to craftsmen and users the advantages of geotherm heat pumps.
However, besides the unquestionably good comfort, they are being won over with unrealistically high saving predictions.
In the reality the promised cost savings appear only very seldom.
Where do the causes lie for these circumstances?

First of all some basics:

An essential criteria for geothermal heat pumps is the so-called annual work number. It is calculated by the relation of heat to the amount of yearly used electricity.
Good heat pumps are marked by an annual work number which is greater than 4.
Furthermore one should know that the power consumption of the heat pump is the bigger, the higher the temperature difference is that the heat pump must bridge.

The ideal case can look like this:

The building to be heated is a new building, with a clearly better insulating capability than the EnEV200 standard in Germany.
A good heat- medium would be hot water which shows a temperature of 10°C.
As a heat-transferring system, a surface heating (under the floor heating or wall heating), where a temperature of 30°C is used.
In this case the heat pump must overcome only 25°C to be able to heat the house, even during cold days.
The annual work number to be expected arrangement will lie approx. at 4.5 or even higher
This way the heat pump can unfold its ecological and economical advantages and does justice to the predictions and requirements of the owner.
If this investment constellation is used, in a typical unreconstructed old building, the operating expenses of a geothermal heat pump become similar to an oil or a gas condensing boiler. Under these circumstances it appears that, the operation of a heat pump is not worthwhile.
Fact: A heat pump is worthwhile only if the annual work number is higher than 4.0.
This examples shows that the source situation of the building may NOT be neglected in any case.
In advertisements, when they say “75% of free energy from the environment”, is simply wrong in the majority of the cases, because the result is not attached any concrete terms.
The reason for the often bad performance of heat pumps, in most cases lie in the change of old heat producers to heat pumps, without other improving or complementary reconstructions to the building such as insulation.

To sum up

Geothermal Heat pumps should go exclusively in the new building where low temperature – under temperature surface heating systems have to be used (under-floor and wall heating systems).

Heat pumps should be chosen with high basic temperatures, like ground water – earth. To use warm pumps with air is not economical.

The hot-water preparation should be backed up with a solar arrangement.

The higher the annual work number of the heat pump, the better.

If we want to use all these different systems, we must decide from case to case, which combination of these systems would be efficient.

In conclusion, my professional opinion is that it is most certainly possible to construct a Geotherm system without use of public energy sources, anywhere.

Links to other Why Go Green – Energy Sources:
Why Go Green – Wind Power
Why Go Green – Photovoltaic System
Why Go Green – Biomass Energysources
Why Go Green – Biogas Technology
Why Go Green – CHP=Compined Heat-Power Plant
Why Go Green – Solar Power Cells>