Comparative scenario-based LCA of renewable energy technologies focused on the end-of-life evaluation

In this article, a comparison was made between the environmental performance of three existing renewable energy systems, namely a photovoltaic, a wind, and a geothermal power plant; particularly, this study is focused on the end-of-life stage. More specifically, a scenario-based Life Cycle Assessment model was developed. It returns a wide range of possible results expressing the eco-profile of the analysed systems; moreover, the interpretation of the results allows pointing out the main priorities to be implemented in a sustainable end-of-life strategy. According to the results, the photovoltaic system can benefit from recycling most in comparison to the other systems, also because the disposal and decommissioning do not determine a large environmental burden. More specifically, the recovery of secondary metals from the structures of the solar arrays and the materials composing the photovoltaic modules (including the metals contained inside the panels) is particularly effective to improve the environmental performance of the system. Concerning the wind farm, the decommissioning operations of the installation site (i.e. the removal and transportation of asphalt, cement and gravel) turn out to be critical for several environmental indicators, as well as the combustion of waste lubricating oil; however, the recovery of metals and construction materials can compensate such environmental issues. The eco-profile of the geothermal system is slightly affected by the end-of-life operations, whether the disposal and the recycling processes. Indeed, the direct emission of pollutants and the consumption of reactants, which are not recycled, represent the main environmental issues. Based on a single score, if the disposal is selected as an end-of-life scenario, the photovoltaic system results as the most impacting system, followed by geothermal and wind. Differently, in case all materials are recycled, the environmental burden of the photovoltaic system assumes intermediate values compared to the wind and geothermal systems.