title: Environmental consequences of future biogas technologies based on separated slurry.
abstract: This consequential life cycle assessment study highlights the key environmental aspects of producing biogas from separated pig and cow slurry, a relatively new but probable scenario for future biogas production, as it avoids the reliance on constrained carbon cosubstrates. Three scenarios involving different slurry separation technologies have been assessed and compared to a business-as-usual reference slurry management scenario. The results show that the environmental benefits of such biogas production are highly dependent upon the efficiency of the separation technology used to concentrate the volatile solids in the solid fraction. The biogas scenario involving the most efficient separation technology resulted in a dry matter separation efficiency of 87% and allowed a net reduction of the global warming potential of 40%, compared to the reference slurry management. This figure comprises the whole slurry life cycle, including the flows bypassing the biogas plant. This study includes soil carbon balances and a method for quantifying the changes in yield resulting from increased nitrogen availability as well as for quantifying mineral fertilizers displacement. Soil carbon balances showed that between 13 and 50% less carbon ends up in the soil pool with the different biogas alternatives, as opposed to the reference slurry management.
authors.affiliation: Institute of Chemical Engineering, Biotechnology and Environmental Technology, Faculty of Engineering, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. loha@kbm.sdu.dk
authors.forename: Lorie
authors.initials: L
authors.lastname: Hamelin
authors.forename: Marianne
authors.initials: M
authors.lastname: Wesnæs
authors.forename: Henrik
authors.initials: H
authors.lastname: Wenzel
authors.forename: Bjørn M
authors.initials: BM
authors.lastname: Petersen
mesh_terms: D000818:Animals; D056804:Biofuels / Q000592:standards*; D002244:Carbon / Q000032:analysis; D002417:Cattle; D004777:Environment; D057232:Global Warming / Q000517:prevention & control*; D055772:Green Chemistry Technology / Q000379:methods* / Q000639:trends*; D008372:Manure; D012680:Sensitivity and Specificity; D012987:Soil / Q000032:analysis; D034421:Sus scrofa
chemical_list: D056804:Biofuels; D008372:Manure; D012987:Soil; D002244:Carbon