Comparative life cycle assessment of modern and conventional biogas based energy systems using anaerobic co-digestion

Biomass conversion into bioenergy through anaerobic co-digestion (ACoD) and commercialization requires reliability in terms of ecological sustainability. This study aimed at investigating the environmental impacts of co-digestion of nitrogen-rich livestock waste: cow dung (CD) and poultry droppings (PD) with carbon-rich lignocellulosic maize cob (MC) for modern electricity production and conventional cooking practice. Life Cycle Assessment (LCA) was conducted for 5 impact categories namely acidification potential (AP), climate change potential (CC), eutrophication potential (EP), malodorous air, and photochemical oxidation potential (POP) for conventional (biogas use in cooking and open storage of digestate) and modern (biogas use to produce electricity and close storage of digestate). Modern practice showed 88–98.5 %, 24.74–53.32 %, 41.91–92.22 % (except PD), and 49.77–57.19 % emissions reduction for AP, CC, EP, and POP, respectively, compared to conventional. In modern practice, the close storage of biogas had significantly reduced emissions. In the case of modern practice, ACoD of CD with MC resulted in 41.14–41.88 % CC, 28.25–70.25 % EP, and 2.68–5.67 % POP reduction compared to mono digestion of CD and MC. On the contrary, co-digestion of PD with MC resulted in a lowering of 56.35–95.42 % EP, and 2.29–12.60 % POP compared to mono-digestion of PD and MC. Leakage from biogas production and electricity generation played a major role in environmental emissions in modern practice. Further LCA study should be carried out considering biogas upgradation and appropriate use of digestate to commercialize biogas use for electricity production. • LCA of modern and conventional anaerobic co-digestion systems is conducted. • Adoption of modern practice helped to reduce 5–99 % emission. • Modern use of biogas for electricity is found environmentally beneficial. • Co-digestion reduced climate change, eutrophication, and photochemical oxidation. • Capture of residual biogas from digestate reduced emissions significantly.