Geologic sinergies for the environment
Monitoring of a closed-loop geothermal pilot plant
(low enthalpy)

Sinergeo follows the thermal monitoring of a 170-kW closed-loop geothermal pilot plant (low enthalpy) in Vicenza, operating since November 2010. The plant is constituted of 42 100m-deep closed-circuit probes and it intercepts valuable confined aquifers already exploited by several public water wells.
 
The thermal monitoring of the local groundwater system was therefore necessary to verify the sustainability of the geo-exchange initiative with respect to the stability of the natural balance of the intercepted groundwater system.
 
In order to verify the hydrological and thermal invariance of the system, a purpose-specific monitoring network has been installed, several sensors have been installed in three different control points: the automatic and continuous acquisitions are spaced every 10 m of depth, to cover the entire length of the vertical probes.
 
Compared to the stable regional groundwater temperature, around 13°C, the measured groundwater temperature drops during the winter period, as heat is extracted from the subsoil to produce space heating. On the contrary, a higher-than-average temperature is recorded in the water table during the summer period, due to cooling activities. Nevertheless, detected fluctuations are very small and no thermal trend is recorded over time.
 
The thermal influence of the system is acceptable, and, above all, the induced perturbation is spatially limited to the surroundings of the single vertical exchanger, not causing any significant environmental imbalance.
 
After 10 years of thermal monitoring of the pilot site, it is possible to validate the results achieved at the site-specific level, confirming the environmental and energy sustainability of the plant on an experimental basis.

This long-term monitoring supports in a technical and scientific way the wishes for greater energy use of the geo-exchange, as renewable energy even in a delicate area already exploited for supplying drinkable water.