Thermal Storage Catching Seasons

In a geothermal plant, calories are extracted from the ground and transferred to the building. It is then necessary to find an energy balance between the needs of the building and what can be supplied by the ground, otherwise the building will exhaust the geothermal resource (cooling of the ground). One can also try to pilot the resource in a symmetric way: instead of extracting calories from the ground, it is possible to transfer calories from the building to the ground. The thermal inertia of the ground can then be used to store temporarily these calories (or frigories), in order to restore them later to the building.

For example, the heat can be extracted from the building during summer and injected in the ground. During winter, part of this heat will be used for heating. In the same time, cold from the building is stored in the ground, and will be used for cooling during the next summer, etc...

Massive heat storage allows thus to postpone the use of an energy produced at low cost during a convenient period. This can be thermal solar energy, or energy wastes (heat thrown back in summer during the cooling of the building).

In this mode of functioning, the geothermal plant and the building live in a cyclic thermal exchange, generally supported by the seasonal cycle - we speak then about interseasonal storage. The building serves as climatic exchanger along the season. The geothermal plant is used in a reversible way as source or as well of heat or cold. A quantity of energy catched some days, weeks or months before is made available for the building.

By using a large proportion of renewable and recycled energies, we minimize the dependence of the building in primary energy and allow a very significant increase of its energy efficiency.

Heat Sources

Any heat source, usually ignored, can be coupled with the geothermal storage. The most common one is the building itself: along the seasons, it is transformed into heat collector during summer and cold collector during winter, if its thermal distribution is appropriate. The use of additional thermal solar panels is useful when the building does not "produce" enough heat. Finally, the heat resulting from industrial engines, or given out by electric or thermal devices can be valued instead of being dissipated in the atmosphere.