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Zawartość zarchiwizowana w dniu 2022-12-27

ENERGY INTEGRATED SYSTEM FOR LOW TEMPERATURE AND LOW DEPTH GEOTHERMAL SOURCE UTILIZATION

Cel

First of all, the project was represented by the confirmation of the geothermal reservoir and of the expected characteristics of the endogenous fluid (flow, temperature, chemical composition).
The second and more important step is represented by the demonstration that the envisaged source, even if characterized by low temperature, can be utilized successfully and give a significant contribution for satisfying the users' thermal needs.
This result shall be obtained through the installation of a pilot plant, conceptually designed in order to be an energy integrated system suitable for the optimization of the production not only of the thermal energy, but also of the electric and cold energy required by the consumer.
The reservoir has been found at 180m depth (instead of 400 m); no other reservoirs were found in spite of the deepening of the drilling down to more than 600 m.
As a consequence, the temperature of the reservoir is much lower than expected (about 16°C instead of 35°C)
Also the available flow (about 1 L/S) is lower than expected; probably because of the invaded cementation occured during the drilling activity.
According to above results, the project became no more exploitable and profitable and, as a consequence, it was abandoned.
The geothermal fluid (50 t/h, 35 deg. C, soft water, estimated depth of the well 500 m) is divided into different streams wellhead : one of them is utilized for providing the heat supply to the evaporator of a heat pump cycle; a second stream shall feed some boilers for sanitary hot water production; a third stream shall supply the pre-heating coils of the air treatment units for the new buildings; finally, a last part of the geothermal flow shall be utilized in future for other initiatives (such as fish farming, greenhouses and so on), not included in the present project.
The first stream, cooled by the heat pump evaporator, shall feed the municipal water distribution network.
The above said heat pump is electrically driven (estimated COP= 4,55; electric power 60 kW; thermal power 273 kW) and the heat delivered at the condenser is utilized in a second heat pump cycle, based on an absorption unit and connected in series with the first heat pump cycle. The estimated COP of the absorption heat pump in winter is 1,7 with a thermal power production of 663 kW.
The heat production at the condenser of the absorption heat pump shall supply the ISMES district network, together with the heat recovery from the cooling circuit (water+oil) of a heat and power gas motor.
On the contrary, the exhaust gases from this motor shall produce 4,5 bar saturated steam, devoted to the supply of the generator of the absorption heat pump.
The electric energy produced by the motor is utilized for ISMES's electric needs. In summer, the absorption heat pump (based on a reversible cycle) shall produce cold energy for the air conditioning of the buildings.
The most relevant innovative aspects of the project are related both to the type of the underground water reservoir and to the flow scheme suggested for the plant.
Even if widely extended, the warm water reservoirs located in several regions of the Po Valley never have been exploited up to now.
On the other side, the flow scheme of thesurface plant is quite original and the different units are assembled according an innovative solution. In particular, the utilization of a reversible absorption heat pump represents a significant improvement of the existing technology for the utilization of low temperature geothermal heat.

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Koordynator

Istituto Sperimentale Modelli e Strutture SpA
Wkład UE
Brak danych
Adres
Viale Giulio Cesare 29
24100 Bergamo
Włochy

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