Objective
The use of geothermal energy from a hot spring to provide 57% of the heating requirements (4,000 Mcal/h) and sanitary hot water for public facilities including a school and a hospital. The project design calls for annual energy savings of 490 TOE. Payback is estimated at 7-8 years.
The hot spring 'La Bollente' is located in the city centre and produces thermal water at 33. 5 m3/h and 70 deg. C.
The project involves the building of a 4. 65 MW central heating station and the installation of a district heating network of pre -insulated stainless steel pipes. Two plate exchangers (2 x 1. 5 MW ) will be used to recover heat from the thermal water and by using gas driven heat pumps (1. 4 MW) heat it to 80 deg. C.
Tests will be performed with a prototype exchanger immersed in the main geothermal feeder.
Optimal use of the geothermal energy is achieved by using the water directly from its source during the low load conditions which exist at various periods. When the load is higher the heat pumps are used and finally, during high load conditions, the heat generators come on line.
The plant may be replicated wherever the heating temperatures required are not too high. The utilisation of natural spring and spa water would generally be economically viable because of the relatively low investment involved. The comparatively low thermal power of this project (2300 th/h) indicates that a district heating network is efficient even if the target is small.
A saving of 500 TOE/yr is obtained.
The system supplies 13 thermal substations serving an equal number of public buildings by means of a network of stainless steel pipes . The thermal energy is produced by a power station which, in addition to traditional heat generators, is also equipped with two endothermal Otto cycle gas driven pumps which use the natural source water with a flow rate of approximately 560 l/min. During the summer and part of the winter the water is conveyed to the Baths where its ostensible curative properties are used in therapeutic programmes.
System control and optimisation is performed by a direct digital control system. This is a centralised control system which runs both the heat generating station and all the substations.
Plant specifications are : Thermal output of the plate heat exchanger - 174 kW, Geothermal water flow rate - 33. 5 m3/h, thermal jump of the geothermal water - 70-35 deg. C, Extension of the network - 3 km.
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
15011 Acqui Terme Alessandria
Italy