Using geothermal energy for heating

Why use a geothermal heating energy source? Shallow geothermal energy is a renewable energy source that offers several exploitation techniques depending on the resources available. It makes it possible to recover the heat present in the ground or in water at depths of less than 200 metres, with temperatures generally below 30°C, usually between 10 and 15°C. There are two main techniques for harnessing ground heat, namely: • Horizontal geothermal energy: This technique uses a network of buried pipes, similar to underfloor heating. A fluid circulates in these pipes to capture the heat of the ground. A heat pump then uses this energy for heating, domestic hot water production, etc. • Vertical geothermal energy: This method uses thermal probes placed in boreholes generally less than 100 metres deep. Again, a fluid circulates in the probes to extract heat from the ground, which is then used by a heat pump for various thermal applications. • Aquathermal energy: this concerns the use of heat from groundwater; the principle is similar to vertical geothermal energy. However, an open loop is used, pumping and discharging groundwater (such as aquifers). A first borehole is used to extract the water, while a second borehole is used to discharge it. A heat pump then captures the heat of the water for domestic hot water production, heating, etc. Geothermal energy has several important advantages: • Reduction of greenhouse gas emissions: Geothermal energy is considered a clean energy source because it does not involve burning fossil fuels, thereby helping to reduce greenhouse gas emissions. • High energy efficiency: Geothermal heating systems are known for their high energy efficiency (COP > 4), which reduces heating costs and delivers long-term energy savings. Unlike other renewable energy sources such as solar or wind, geothermal energy is not subject to climatic variations or weather conditions, making it a reliable and constant energy source. • Versatile applications: Geothermal energy can be used to heat residential, commercial and industrial buildings, as well as to heat swimming pools, produce domestic hot water and for other thermal uses. It can also be combined with geothermal cooling systems, offering versatile use of this energy source. How to set up a geothermal heating energy source? It is important to note that setting up a geothermal system requires specialised expertise. It is recommended to use qualified professionals experienced in geothermal energy to carry out the study, design, installation and maintenance of the system. General steps to follow: • Feasibility study: it is important to start with a feasibility study to assess the viability of geothermal energy as a heating energy source in the region concerned. This includes analysing the geological characteristics of the ground, the availability of geothermal resources and the technical and economic feasibility of the project. • System design with the help of a qualified professional to design the geothermal system suited to the needs. This involves determining the appropriate technique (horizontal geothermal, vertical geothermal or aquathermal), the size of the system, the types of thermal probes, the heat pump equipment, etc. • Obtaining authorisations: this involves checking the legal and regulatory requirements of the region concerned regarding the installation of geothermal systems. It may be necessary to obtain authorisations, building permits or specific approvals before proceeding with the installation. • Installation of the thermal probes: depending on the technique chosen, the thermal probes will be installed either horizontally in the ground, vertically using boreholes, or using water wells for aquathermal energy. This step requires specialised skills and must be carried out by specialised companies. • Installation of the heat pump system inside the building to exploit the heat captured by the thermal probes. This includes installing the heat pump itself, the control devices and the auxiliary equipment. • Connection to the heating system: the geothermal system must be properly connected to the building’s existing heating system. This may require modifications or adjustments to integrate the new equipment efficiently and safely. • Commissioning and testing: once the installation is complete, the geothermal system must be commissioned and tested to ensure it works properly. Adjustments may be needed to optimise the system’s performance and guarantee maximum energy efficiency. • Maintenance and monitoring: to ensure the continued proper operation of the geothermal system, it is important to carry out regular maintenance and monitoring to track performance, check components, carry out repairs if necessary and maximise the system’s energy efficiency.

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