Water footprint within waste to energy plants: Padova waste to energy plant as a case study

Waste-to-energy (WTE) plants are a substantial part of modern waste management methods, by converting non-recyclable waste into energy. Even though they promise unavoidable environmental benefits, significant water resources, particularly for cooling processes, are required for the processing, which conclusively leads to their overall water footprint. Advanced cooling technologies and internal water recycling systems propose ways to alleviate water consumption of these plants. Life Cycle Assessment (LCA) is a valuable methodology which is widely used in different industries, including waste management to understand the environmental impact of a system or process throughout its entire life. In recent years, studies on waste-to-energy plants are gaining attention where LCA helps assess the overall environmental efficiency of waste-to-energy plants. LCA can also be used to analyze the water footprint associated with WTE plants, which can be a valuable insight for improving the efficiency and sustainability of such facilities. This thesis assesses the water consumption associated with the electricity generation process within WTE plants, using the San Lazzaro WTE plant in Padova, Italy, as a case study. By employing the Life Cycle Assessment (LCA) methodology, this research quantifies the environmental impacts of a waste-to-energy facility, with a main focus given to water footprint and explores opportunities to intensify the sustainability of cooling and other operations. As a main source of water consumption within waste management facilities, the description of various cooling technologies is incorporated in this study, analyzing their performance in reducing freshwater dependency and environmental impact. Moreover, a comparison of cooling water consumption between the two different cooling systems in the same plant will be presented. The system boundaries of this study cover the entire process from the arrival of municipal solid waste at the waste-to-energy plant to the release of emissions into the environment. Specifically, the analysis begins at the plant gate, where waste is received, and follows through key stages, including waste incineration, energy generation, flue gas treatment, and cooling. The boundaries extend to the final release of emissions into water bodies, discharge to sewage systems, and any residual waste management processes. The data for the assessment is taken from Padova WTE plant annual report and coupled with literature and Ecoinvent database inputs. The LCA is conducted using the SimaPro software, and the impact assessment is performed using the Environmental Footprint 3.1 and AWARE methods. This study evaluates how different cooling technologies affect the water footprint of the case study plant. The plant’s current cooling system is compared against hypothetical scenario employing alternative cooling method, quantifying changes in water consumption per kWh of energy generated. Results highlight the potential for reducing water usage through technology selection, providing insights for sustainable WTE operation optimization. In the literature there is a lack of LCA studies that consider environmental and water footprint of WTE plants. Therefore, the findings from this research, may be the baseline for supporting the future projects related to the life cycle assessment of cooling systems and environmental impacts of each process stage in plants producing energy from municipal solid waste.