A tool for evaluating geothermal power exploitability and its application to Ischia, Southern Italy

Abstract

h i g h l i g h t sA method to evaluate the potential for electric power production at geothermal sites. It evaluates geofluid's flow rate, pressure, temperature and non-condensable gases. It defines the best plant option and finally returns the actual available power. a r t i c l e i n f o b s t r a c tThe paper proposes a method to evaluate the potential for electric power production at any site of possible geothermal interest. Accounting for geological data of the reservoirs, the method allows the computation of the available electrical power of the investigated site. Electrical energy production from geothermal sources is realized through different techniques, such as single flash and double flash, dry steam, and binary ORC plants. The technique chosen to be the most productive is determined by analyzing a specific range of geofluid properties, mainly temperature and pressure. Moreover, each plant typology has a global efficiency that may be correlated to geofluid enthalpy by empiric relations available in literature. The proposed evaluation method brings together all these correlations, yielding the power availability from a geosource, once its temperature and pressure are known. The method takes as input the geofluid available flow rate, its pressure, temperature and non-condensable gas content. It defines the best plant option from these parameters, calculates its global efficiency and finally returns the actual available power. For sites of geothermic interest, such as the volcanic island of Ischia in Southern Italy, the results of the application of this new method clearly highlight the most suitable zones for power plants installations.

Magnetic Structure of the Ischia volcanic island, Southern Italy

“…In this paper, we present a study of the geo-structural setting of the island of Ischia based on the combined analysis of these datasets. We support our interpretation by a previous modeling of potential field data and by the temperature data measured in deep thermal wells of the island [Paoletti et al 2015].…”

“…This result was confirmed by a recent study on the geothermal potential of the island [Paoletti et al 2015], which highlighted the south-western sector of the island as the most suitable zone for power plants installations. A joint modeling of the magnetic and gravity long-period components along a profile [Paoletti et al 2013] pointed out the presence of a structure with a density of 2.4 g/cm3 and variable magnetization, whose top is located at 1200-1750 m b.s.l.…”

GeoThermag: A geothermal magnetic refrigerator

“… is the temperature of the undisturbed ground  r b is the radius of the hole that housed the probe  is the linear thermal power transferred by the probe through the boiler that is measured by knowing the electrical power supplied and the total length of the probe, which is interpreted as the depth of the hole  is the thermal diffusivity of the ground estimated from the average values available in the literature (Zarrella et al, 2013;Paoletti et al, 2015)  is Euler's constant and is equal to 0.5772  is the thermal conductivity of the ground  is the equivalent thermal resistance of the coupled probe-filling material.…”

Energy Exploitation of High-Temperature Geothermal Sources in Volcanic Areas—a Possible ORC Application in Phlegraean Fields (Southern Italy)

“…It is worth noting that, nowadays, most geothermal installations present electric power higher than 200 kWel, whereas few applications on small-scale The actual contribution of the heat beneath the surface of solid earth to the national electric production is limited to the Toscana region (Central Italy), even though high potential exists in the rest of the Italian peninsula and specific incentives are defined by the national legislation [14][15][16]. Furthermore, the exploitation of the active volcanic area represents a promising option due to the high temperature reservoirs' availability [17][18][19][20][21]. Nevertheless, few studies exist in the literature; for this reason, the present work focuses on the possible valorisation of geothermal sources in the active volcanic area of Phlegraean Fields Caldera (Southern Italy) by adopting small-scale Organic Rankine Cycle (ORC) units.…”