Geothermal district heating: Energy, environmental and economic analysis of a case study in northern Italy

Department of Energy, Polytechnic of Milano, Italy

Abstract

Geothermal district heating is a technology that has been established for over 50 years and offers a number of significant advantages. It allows multiple homes to be converted to renewable energy sources simultaneously, allows a stable heat supply with long-term fixed prices, and generally presents lower risks. The utilization of geothermal energy as a heat source for the network can be considered cost-free during operation, but has a critical economic aspect related to the initial investment. Geothermal district heating networks are in fact capital-intensive systems (CapEx), requiring substantial investments for the installation of the geothermal infrastructure. However, operating costs (OpEx) are significantly lower compared to conventional systems. This study examined the implementation of a district heating network in a medium-sized city in northern Italy. An energy and environmental impact assessment was conducted to determine the optimal plant configuration that maximises the use of the geothermal resource and minimises greenhouse gas emissions. Additionally, a sensitivity analysis was carried out to assess the impact of market variables on the overall cost of implementing the district heating network. This included an evaluation of changes in investment costs in response to variations in the value of electricity taxes -oneri di sistema-, of the revenues from the sale of thermal and electrical energy, as well as of the fuel costs. This study aims to provide a complete and detailed overview of the energy, environmental and economic implications associated with the implementation of a geothermal district heating network