A comparison between energy conversion systems for a power plant in Campi Flegrei geothermal district based on a WellBore Heat eXchanger

Abstract

One of the more complex issues in the geothermal plants is the re-injection of the fluids. This operation has multiple goals but it entail high economic costs. A possible alternative is the use of an indirect system to extract heat, the WellBore Heat eXchanger (WBHX). This kind of well completion allows to extract heat using an heat carrier fluid circulating in a closed loop, therefore it could be a solution to extract heat from unconventional geothermal systems, such as magmatic reservoirs like Campi Flegrei (Italy). The main weakness of the WBHX is a low heat recovery efficiency respect to a conventional geothermal technology. In order to maximize the conversion of the thermal energy into electricity, the paper is focused on the comparison of two different systems: an ORC power plant and a Stirling motor.