Sources of variability in greenhouse gas and energy balances for biofuel production: a systematic review

Whitaker, Jeanette, Ludley, Katherine E., Rowe, Rebecca, Taylor, Gail and Howard, David C. (2010) Sources of variability in greenhouse gas and energy balances for biofuel production: a systematic review. GCB Bioenergy, 99-112. (doi:10.1111/j.1757-1707.2010.01047.x).


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Across the energy sector, alternatives to fossil fuels are being developed, in response to the dual drivers of climate change and energy security. For transport, biofuels have the greatest potential to replace fossil fuels in the short-to medium term. However, the ecological benefits of biofuels and the role that their deployment can play in mitigating climate change are being called into question. Life Cycle Assessment (LCA) is a widely used approach that enables the energy and greenhouse gas (GHG) balance of biofuel production to be calculated. Concerns have nevertheless been raised that published data show widely varying and sometimes contradictory results. This review describes a systematic review of GHG emissions and energy balance data from 44 LCA studies of first- and second-generation biofuels. The information collated was used to identify the dominant sources of GHG emissions and energy requirements in biofuel production and the key sources of variability in published LCA data. Our analysis revealed three distinct sources of variation: (1) 'real' variability in parameters e.g. cultivation; (2) 'methodological' variability due to the implementation of the LCA method; and (3) 'uncertainty' due to parameters rarely included and poorly quantified. There is global interest in developing a sustainability assessment protocol for biofuels. Confidence in the results of such an assessment can only be assured if these areas of uncertainty and variability are addressed. A more defined methodology is necessary in order to allow effective and accurate comparison of results. It is also essential that areas of uncertainty such as impacts on soil carbon stocks and fluxes are included in LCA assessments, and that further research is conducted to enable a robust calculation of impacts under different land-use change scenarios. Without the inclusion of these parameters, we cannot be certain that biofuels are really delivering GHG savings compared with fossil fuels

Item Type: Article
Digital Object Identifier (DOI): doi:10.1111/j.1757-1707.2010.01047.x
ISSNs: 1757-1693 (print)
1757-1707 (electronic)
Keywords: biofuel, carbon, energy, greenhouse gas, life cycle, assessment, sustainable
Subjects: T Technology > TD Environmental technology. Sanitary engineering
Q Science > QH Natural history > QH301 Biology
Divisions : University Structure - Pre August 2011 > School of Biological Sciences
ePrint ID: 160033
Accepted Date and Publication Date:
June 2010Published
Date Deposited: 12 Jul 2010 10:09
Last Modified: 31 Mar 2016 13:28
Understanding processes determining soil carbon balances under perennial bioenergy crops CARBO-BIOCROP
Funded by: NERC (NE/H010718/1)
Led by: Gail Taylor
4 January 2010 to 3 January 2015

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