Exergoeconomic and Environmental Evaluation of a Ground Source Heat Pump System for Reducing the Fossil Fuel Dependence: A Case Study in Rome

Abstract

By 2050, the European Commission aims to achieve a 90% reduction in greenhouse gas emissions within the construction sector due to new targets set for greenhouse gases by the Commission. One of the most effective solutions for mitigating the environmental impact of buildings is to integrate renewable-energy systems such as air-to-water heat pumps or geothermal heat pumps. Several works in the literature investigated the advantages of heat pumps, particularly ground source heat pumps, for specific contexts. Furthermore, the evaluation can encompass not only energy considerations but also exergetic aspects, and this paper makes a significant contribution to the latter. The study presented here applies exergy analysis to a geothermal heat pump system that is interconnected with photo-voltaic and solar collector systems in a building located in Rome. Feasibility and environmental assessments were also conducted. It is evident that the exergy efficiency obtained is much lower than the energy efficiency. The heat pump demonstrates higher exergy efficiency by producing high-temperature thermal power compared to a constant dead state at relatively low temperatures. Following the heat pump, the adiabatic mixer exhibits the second highest exergy efficiency, trailed by two heat exchangers. Compared to a conventional plant case, the money saved is EUR 16,772 per year, translating to a Payback Period of 23 years. Furthermore, the average annual reduction in fossil fuel emissions is estimated at 26.2 metric tons of CO2.