Exploitation of low enthalpy geothermal resource: case study of a coastal area affected by seawater intrusion

Abstract

The exploitation of geothermal energy suitable for direct uses is still very limited in Italy. However, recently the interest in it is growing, especially for winter heating and summer cooling. Of particular interest, are the open-loop geothermal systems that are specially attractive in the coastal areas, where the aquifers are generally shallow, though often affected by seawater intrusion. In this work, a detailed characterization of a costal karst area near Bari (Southern Italy), is given as knowledge-base for the exploitation of low enthalpy geothermal resource. At the purpose, a specifically defined monitoring network, consisting of 35 wells, is used to monitor groundwater parameters (temperature, water level, electrical conductivity). The influence of an open-loop geothermal systems on the sea water intrusion is also studied by means of a long-term pumping test, although the results of the test will not be discussed in this paper. The poor groundwater quality, its constant and relative high temperature, and the good productivity of aquifer, make the study area suitable for the installation of geothermal systems. Particular attention must be paid to high salinity and hardness of groundwaters that can lead to fouling and corrosions in machines, reducing their performance. Overall, the experimental approach used for this study represents a good effort to define a standard methodology to characterize a coastal area and to evaluate its geothermal potential. Abbreviation: T, temperature; EC, Electrical Conductivity.