The influence of energy output and substitution on the environmental impact of waste-to-energy operation: quantification by means of a case study

A life cycle assessment (LCA) was conducted to evaluate the total environmental impact of state-of-the-art waste-to-energy (WtE) in Belgium with respect to recovered energy utilization and addition of carbon capture and storage (CCS). Four energy output scenarios were modeled on Umberto LCA software using primary data of mass and energy flows surrounding the six incinerators at the considered WtE plant and predefined processes from the Ecoinvent 3.6 database. The normalized LCA results suggest that by utilizing all the recovered energy as high-pressure steam, the WtE plant can avoid an equivalent annual environmental impact value of approximately 21200, 36800, 6700, 15800, 37000, and 6900 average European citizens in the impact categories 'climate change,' freshwater and terrestrial acidification,' freshwater eutrophication,' photochemical ozone creation,' respiratory effects, inorganics,' and 'terrestrial eutrophication,' respectively. The 'Electricity and Steam with CCS' scenario resulted in the most avoided environmental impact in the impact category 'climate change.' However, in all other impact categories, it resulted in less avoided environmental impact compared to the 'Steam' scenario. The comparative analysis showed that 19 out of the 24 LCA results varied by more than 50% between a region-specific and a region- and fuel-specific model, thus quantifying the influence of scenario uncertainty, introduced by the normative choice of substituted processes in LCA modeling. This study exemplifies the environmental benefit WtE technology can realize by substituting conventional energy production processes that are reliant on fossil resources, while performing its primary function that is reducing the volume of non-recyclable waste, destroying hazardous organic components it contains, and recovering useful materials from it. [GRAPHICS] .