Life cycle analysis of a photovoltaic driven reversible heat pump

Abstract

The growing concerns over the extensive dependence of the cooling and heating sector on conventional sources along with the EU targets for increasing penetration of renewables in residential applications have increased the importance of energy transition and electrification of final uses. Among these, photovoltaic (PV) driven heat pumps are the most competitive solutions from a techno-economic viewpoint. This study aims to quantify and assess the environmental benefits of the aforementioned solution by conducting a Life Cycle Assessment in comparison to different conventional heating and cooling alternatives, including separate production of electricity and heat, grid connected heat pumps and solar absorption systems. An average residential building of 100 m2 located in Milan, Italy, is selected as case study. The equivalent CO₂ emissions from the PV driven heat pumps are estimated to be 71.8 kg/MWh, while the respective emissions of a solar absorption system are estimated to be 150.4 kg/MWh. Moreover, sensitivity analysis is conducted to analyze the effect on the overall environmental performance of different key parameters, including the system’s location during the use phase and the number of the used PV panels. Results indicate that CO₂ equivalent emissions in Trapani, where the best performance in global warming is presented, are lower by 57% compared to Bolzano which presents the worst performance. On the other hand, the number of installed PV panels reaches an optimal value beyond which the benefits of the excess of electricity production are counter-balanced by the added footprint by the manufacturing and end-of-life footprints. It was found that the 4 PVs system has a reduced impact by 57% in global warming, compared to the conventional heat pump, while the impact is lower only by 1% compared to the 5 PVs solution.