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Consequential life cycle assessment of biogas, biofuel and biomass energy options within an arable crop rotation

Styles, D. and Gibbons, J. and Williams, A.P. and Dauber, J. and Stichnothe, H. and Urban, B. and Chadwick, D.R. and Jones, D.L. (2015) Consequential life cycle assessment of biogas, biofuel and biomass energy options within an arable crop rotation. GCB Bioenergy, 7 (6). pp. 1305-1320. DOI: 10.1111/gcbb.12246

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Abstract

Feed in tariffs (FiTs) and renewable heat incentives (RHIs) are driving a rapid expansion in anaerobic digestion (AD) coupled with combined heat and power (CHP) plants in the UK. Farm models were combined with consequential life cycle assessment (CLCA) to assess the net environmental balance of representative biogas, biofuel and biomass scenarios on a large arable farm, capturing crop rotation and digestate nutrient cycling effects. All bioenergy options led to avoided fossil resource depletion. Global warming potential (GWP) balances ranged from -1732kgCO(2)eMg(-1) dry matter (DM) for pig slurry AD feedstock after accounting for avoided slurry storage to +2251kgCO(2)eMg(-1) DM for oilseed rape biodiesel feedstock after attributing indirect land use change (iLUC) to displaced food production. Maize monoculture for AD led to net GWP increases via iLUC, but optimized integration of maize into an arable rotation resulted in negligible food crop displacement and iLUC. However, even under best-case assumptions such as full use of heat output from AD-CHP, crop-biogas achieved low GWP reductions per hectare compared with Miscanthus heating pellets under default estimates of iLUC. Ecosystem services (ES) assessment highlighted soil and water quality risks for maize cultivation. All bioenergy crop options led to net increases in eutrophication after displaced food production was accounted for. The environmental balance of AD is sensitive to design and management factors such as digestate storage and application techniques, which are not well regulated in the UK. Currently, FiT payments are not dependent on compliance with sustainability criteria. We conclude that CLCA and ES effects should be integrated into sustainability criteria for FiTs and RHIs, to direct public money towards resource-efficient renewable energy options that achieve genuine climate protection without degrading soil, air or water quality

Item Type: Article
Subjects: Research Publications
Departments: College of Natural Sciences > School of Environment, Natural Resources and Geography
Date Deposited: 14 Feb 2015 03:28
Last Modified: 14 Apr 2016 02:34
ISSN: 1757-1707
Publisher's Statement: This is the peer reviewed version of the following article: "Consequential life cycle assessment of biogas, biofuel and biomass energy options within an arable crop rotation", which has been published in final form at http://dx.doi.org/10.1111/gcbb.12246 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
URI: http://e.bangor.ac.uk/id/eprint/3459
Identification Number: DOI: 10.1111/gcbb.12246
Publisher: John Wiley & Sons
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