Environmental life cycle assessment of spent coffee ground pellet

Abstract

Coffee, the most globally prevalent beverage, entails environmental and economic consequences due to the high content of toxic compounds in leftover from brewing. Waste-to-energy technologies propose recovering energy from solid or liquid wastes via various treatment methods. This study investigates the environmental performance of the spent coffee ground application in pellet production as a valuable bio-product by life cycle assessment. System boundaries comprise four stages: (1) spent coffee ground collection; (2) pellet production; (3) thermal energy generation; and (4) waste disposal. The LCA model is interpreted by ReCipe 2016 in both midpoint and endpoint levels per 1 MJ of thermal energy as functional unit. Alternative waste-to-energy approaches into transesterification, pyrolysis, and direct combustion of spent coffee ground are also assessed. The impact assessment shows that the pelletizing process significantly contributes to all impact categories except ozone formation and terrestrial ecotoxicity, which is influenced primarily by the transportation process in the spent coffee ground collection stage. The spent coffee ground pellet can lead to climate change mitigation, and reduction in freshwater eutrophication and use of resources due to credits from ash disposed to landfill. Biodiesel is the worst potential option among alternative scenarios, while pellet production and bio-oil demonstrate the most favorable environmental profiles for all impact categories. Damage assessment indicates that pellet production and alternative scenarios mainly influence human health.