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Acquaye A.A.,University of York | Wiedmann T.,University of York | Wiedmann T.,Center for Sustainability Accounting | Feng K.,University of Leeds | And 6 more authors.
Environmental Science and Technology | Year: 2011

It is expected that biodiesel production in the EU will remain the dominant contributor as part of a 10% minimum binding target for biofuel in transportation fuel by 2020 within the 20% renewable energy target in the overall EU energy mix. Life cycle assessments (LCA) of biodiesel to evaluate its environmental impacts have, however, remained questionable, mainly because of the adoption of a traditional process analysis approach resulting in system boundary truncation and because of issues regarding the impacts of land use change and N 2O emissions from fertilizer application. In this study, a hybrid LCA methodology is used to evaluate the life cycle CO 2 equivalent emissions of rape methyl ester (RME) biodiesel. The methodology uses input-output analysis to estimate upstream indirect emissions in order to complement traditional process LCA in a hybrid framework. It was estimated that traditional LCA accounted for 2.7 kg CO 2-eq per kg of RME or 36.6% of total life cycle emissions of the RME supply chin. Further to the inclusion of upstream indirect impacts in the LCA system (which accounted for 23% of the total life cycle emissions), emissions due to direct land use change (6%) and indirect land use change (16.5%) and N 2O emissions from fertilizer applications (17.9%) were also calculated. Structural path analysis is used to decompose upstream indirect emissions paths of the biodiesel supply chain in order to identify, quantify, and rank high carbon emissions paths or 'hot-spots' in the biodiesel supply chain. It was shown, for instance, that inputs from the 'Other Chemical Products' sector (identified as phosphoric acid, H 3PO 4) into the biodiesel production process represented the highest carbon emission path (or hot-spot) with 5.35% of total upstream indirect emissions of the RME biodiesel supply chain. © 2011 American Chemical Society. Source


Wiedmann T.,Center for Sustainability Accounting | Barrett J.,Center for Sustainability Accounting
Sustainability | Year: 2010

We present a comprehensive review of perceptions and methods around the Ecological Footprint (EF), based on a survey of more than 50 international EF stakeholders and a review of more than 150 original papers on EF methods and applications over the last decade. The key points identified in the survey are that the EF (a) is seen as a strong communication tool, (b) has a limited role within a policy context, (c) is limited in scope, (d) should be closer aligned to the UN System of Environmental and Economic Accounting and (e) is most useful as part of a basket of indicators. Key issues from the review of methods are: (a) none of the major methods identified can address all relevant issues and questions at once, (b) basing bioproductivity calculations on Net Primary Production (NPP) is a promising approach, (c) advances in linking bioproductivity with ecosystem services and biodiversity have been made by the Dynamic EF concept and the HANPP indicator, (d) environmentally extended input-output analysis (IOA) provides a number of advantages for improving EF calculations and (e) further variations such as the emergy-based concept or the inclusion of further pollutants are not regarded as providing a fundamental shift to the usefulness of EF for policy making. We also discuss the implications of our findings for the use of the EF as a headline indicator for sustainability decision-making. © 2010 by the authors. Source

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