title: Choosing co-substrates to supplement biogas production from animal slurry--a life cycle assessment of the environmental consequences.
abstract: Biogas production from animal slurry can provide substantial contributions to reach renewable energy targets, yet due to the low methane potential of slurry, biogas plants depend on the addition of co-substrates to make operations profitable. The environmental performance of three underexploited co-substrates, straw, organic household waste and the solid fraction of separated slurry, were assessed against slurry management without biogas production, using LCA methodology. The analysis showed straw, which would have been left on arable fields, to be an environmentally superior co-substrate. Due to its low nutrient content and high methane potential, straw yields the lowest impacts for eutrophication and the highest climate change and fossil depletion savings. Co-substrates diverted from incineration to biogas production had fewer environmental benefits, due to the loss of energy production, which is then produced from conventional fossil fuels. The scenarios can often provide benefits for one impact category while causing impacts in another.
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark. Electronic address: rpw170@alumni.ku.dk.
authors.forename: Giovanna Catalina
authors.initials: GC
authors.lastname: Croxatto Vega
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark. Electronic address: mtho@plen.ku.dk.
authors.forename: Marieke
authors.initials: M
authors.lastname: ten Hoeve
authors.affiliation: Department of Management Engineering, Technical University of Denmark, Produktionstorvet, Building 424, 2800 Kongens Lyngby, Denmark. Electronic address: birk@dtu.dk.
authors.forename: Morten
authors.initials: M
authors.lastname: Birkved
authors.affiliation: Institute of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Niels Bohrs Allé 1, 5230 Odense M, Denmark. Electronic address: sgs@kbm.sdu.dk.
authors.forename: Sven G
authors.initials: SG
authors.lastname: Sommer
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark. Electronic address: sab@plen.ku.dk.
authors.forename: Sander
authors.initials: S
authors.lastname: Bruun
mesh_terms: D000818:Animals; D056804:Biofuels / Q000382:microbiology*; D057231:Climate Change; D003246:Conservation of Energy Resources / Q000379:methods*; D004777:Environment; D005068:Eutrophication; D005735:Garbage; D008372:Manure / Q000382:microbiology*; D008697:Methane / Q000096:biosynthesis*; D008962:Models, Theoretical; D018547:Plant Stems / Q000737:chemistry / Q000378:metabolism*; D013552:Swine
chemical_list: D056804:Biofuels; D008372:Manure; D008697:Methane
keywords: Biogas; Life cycle assessment; Organic fraction household waste; Separated slurry; Straw