title: Life Cycle Assessment of Biogas Production in Small-scale Household Digesters in Vietnam.
abstract: Small-scale household digesters have been promoted across Asia as a sustainable way of handling manure. The major advantages are that they produce biogas and reduce odor. However their disadvantages include the low recycling of nutrients, because digestate is dilute and therefore difficult to transport, and the loss of biogas as a result of cracks and the intentional release of excess biogas. In this study, life cycle assessment (LCA) methodology was used to assess the environmental impacts associated with biogas digesters in Vietnam. Handling 1,000 kg of liquid manure and 100 kg of solid manure in a system with a biogas digester reduced the impact potential from 4.4 kg carbon dioxide (CO2) equivalents to 3.2 kg CO2 equivalents compared with traditional manure management. However, this advantage could easily be compromised if digester construction is considered in the LCA or in situations where there is an excess of biogas which is intentionally released. A sensitivity analysis showed that biogas digesters could be a means of reducing global warming if methane emissions can be kept low. In terms of eutrophication, farms with biogas digesters had 3 to 4 times greater impacts. In order to make biogas digesters sustainable, methods for recycling digestates are urgently required.
authors.affiliation: National Institute of Animal Sciences, Hanoi 10000, Vietnam .
authors.forename: T K V
authors.initials: TK
authors.lastname: Vu
authors.affiliation: Vietnamese Academy of Agricultural Sciences, Thanh Tri, Hanoi 10000, Vietnam . ; Vietnamese Academy of Agricultural Sciences, Thanh Tri, Hanoi 10000, Vietnam .
authors.forename: D Q
authors.initials: DQ
authors.lastname: Vu
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C., Denmark .
authors.forename: L S
authors.initials: LS
authors.lastname: Jensen
authors.affiliation: Department of Chemical Engineering, Biotechnology and Environmental Technology, Faculty of Engineering, University of Southern Denmark, 5230 Odense, Denmark .
authors.forename: S G
authors.initials: SG
authors.lastname: Sommer
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C., Denmark .
authors.forename: S
authors.initials: S
authors.lastname: Bruun
keywords: Digestate; Euthrophication; Global Warming; Manure; Methane