Geothermal energy for single-family homes is the ideal solution for the future

If we talk about sustainable architecture, we cannot ignore the use of renewable energy as an option to take into account when planning projects. In another post, we talked about wind energy, solar thermal, solar photovoltaic, and acroteria.

In this sense, we want to talk to you about geothermal, renewable energy from the ground. It is an energy source that takes advantage of the heat from the subsoil to produce hot water, heating, and air conditioning.

When they have asked me for an opinion on the type of environmentally friendly energy that I would recommend for the construction of a single-family home, I always answer them that, without a doubt, they opt for geothermal energy to cover the needs of heating, sanitary hot water (DHW) and refrigeration.

At the initiative of the Community of Madrid, a Geothermal Energy Guide has been published prepared by the UPM Mining Engineers, Guillermo Llopis Trillo, and Vicente Rodrigo Angulo. Based on this guide, and on blog posts specialized in the matter, among which I would highlight the one from Click Removable, I am going to give you a brief summary of this type of installation and its results.

First of all, we are going to define what geothermal energy and geothermal air conditioning consist of. As indicated in the aforementioned documents, geothermal energy is defined as the energy stored in the form of heat below the solid surface of the earth.

This energy (heat) is very high in some regions of the earth where there are volcanoes and where geysers or hot springs abound. In these places, the energy provided by the earth is used to supply hot water and heating to homes, but on most of the planet this does not happen and the temperature of the earth in the subsoil, a few meters from the surface, remains stable between 7ºC and 14ºC, thanks to the heat supplied by its incandescent core at a depth of about 6,300 km.

This circumstance, together with the enormous thermal inertia of the subsoil, that is, its resistance to changing that temperature, allows us to have a source or sink of heat at a constant temperature, be it winter or summer. This is the basis of the so-called geothermal air conditioning, which allows us to heat the house in winter and cool it in summer with minimal energy expenditure (generally electrical).

For this, it is necessary to install a network of collector tubes at a certain depth in the ground through which a cooling fluid will circulate that will capture the heat from the ground (between 7 ºC and 14 ºC, as we have said). By means of a pump, the operation of which is described later, this fluid will be circulated in such a way that either its temperature will rise to 25 or 26ºC to warm the home in winter, or it will be left as is, above 14ºC. to cool it in summer. This small effort to raise the temperature by about 10 ºC or 12 ºC in winter and to “transfer the cool” in summer is carried out by using a highly energy-efficient device (it consumes little energy and produces a lot of energy) called a “heat pump. ”.

This network of collecting tubes can be of three types:

As mentioned before, geothermal air conditioning employs a key element: the geothermal heat pump. Its principle of operation is the same as that of refrigerators and air conditioners. The difference lies in two important issues:

This particularity makes geothermal heat pumps extremely efficient. With its use, a ratio of approximately 4 is obtained between the heat energy (or refrigeration) delivered and the electrical energy consumed. In other words, for every KW of electrical energy consumed we obtain about 4 KW of heating or cooling energy to heat or cool the home.

And how can this be without contradicting the principle of conservation of energy which postulates that energy is neither created nor destroyed but simply transformed? Well, very simple: that additional energy is offered to us free of charge by the enormous heat stored below the surface of the earth, captured through the network of collector tubes described above.

The network of outer and inner tubes exchange their roles in winter and summer, acting as heat sinks or as heat sinks as the case requires. And this game is made by the wonderful geothermal heat pump.

The network of external collector tubes is, in general, different and independent from the internal radiant network. To do this, to separate these two tube networks, ‘ heat exchangers ‘ are used, which serve to transfer heat from one network to another without appreciable loss of energy. This separation between the two tube networks makes it possible to simplify the maintenance of the system.

Among the benefits for the environment geothermal air conditioning we can highlight the following:

It is renewable energy since it comes from the heat produced inside the earth, which is practically inexhaustible.

It is clean energy since there is no combustion.

It is continuous energy, without possible cuts.

It is an energy that is produced locally.

It is an energy that is very economical in its exploitation.

And, as we mentioned in a previous post, the advantage of geothermal energy over aerothermal energy is that, regardless of the time of year and how extreme the climate may be, the source (and sink) of heat is always within reach. the same temperature or subject to very little variation (between 7ºC and 14ºC), which allows the heat pump to work within very constant parameters on which the system can be adjusted to work with maximum performance.