Search

Summary: The divide between attributional and consequential research perspectives partly overlaps with the long‐standing methodological discussions in the life cycle assessment (LCA) and input‐output analysis (IO) research communities on the choice of techniques and models for dealing with situations of coproduction. The recent harmonization of LCA allocations and IO constructs revealed a more diverse set of coproduction models than had previously been understood. This increased flexibility and transparency in inventory modeling warrants a re‐evaluation of the treatment of coproduction in analyses with attributional and consequential perspectives. In the present article, the main types of coproductions situations and of coproduction models are reviewed, along with key desirable characteristics of attributional and consequential studies. A concordance analysis leads to clear recommendations, which call for important refinements to current guidelines for both LCA/IO practitioners and database developers. We notably challenge the simple association between, on the one hand, attributional LCA and partition allocation, and on the one hand, consequential LCA and substitution modeling. [ABSTRACT FROM AUTHOR]

Summary: Many countries see biofuels as a replacement to fossil fuels to mitigate climate change. Nevertheless, some concerns remain about the overall benefits of biofuels policies. More comprehensive tools seem required to evaluate indirect effects of biofuel policies. This article proposes a method to evaluate large‐scale biofuel policies that is based on life cycle assessment (LCA), environmental extensions of input‐output (I‐O) tables, and a general equilibrium model. The method enables the assessment of indirect environmental effects of biofuels policies, including land‐use changes (LUCs), in the context of economic and demographic growth. The method is illustrated with a case study involving two scenarios. The first one describes the evolution of the world economy from 2006 to 2020 under business as usual (BAU) conditions (including demographic and dietary preferences changes), and the second integrates biofuel policies in the United States and the European Union (EU). Results show that the biofuel scenario, originally designed to mitigate climate change, results in more greenhouse gas emissions when compared to the BAU scenario. This is mainly due to emissions associated with global LUCs. The case study shows that the method enables a broader consideration for environmental effects of biofuel policies than usual LCA: Global economic variations calculated by a general equilibrium economic model and LUC emissions can be evaluated. More work is needed, however, to include new biofuel production technologies and reduce the uncertainty of the method. [ABSTRACT FROM AUTHOR]

Recently, Merciai and Heijungs (2014) demonstrated that monetary input–output (IO) analysis can lead to system descriptions that do not conserve mass when the assumption of homogeneous prices is violated. They warn that this violation of basic balance laws can lead to biased estimates of environmental impacts, and they therefore recommend performing IO analysis in a physically accounted framework. We take a broader scope on this issue and present price inhomogeneity as a special case of product mix inhomogeneity. We demonstrate that even a fully physically accounted IO analysis or lifecycle assessment will violate balance laws if it suffers from inhomogeneous aggregation. The core issue is not whether a system is described using monetary or physical units, but rather whether product groups are too aggregated to allow for the concurrent respect of energy, mass, financial and elemental balances. We further analyze the link between the violation of physical balances and the introduction of biases. We find that imbalances are neither a necessary nor a sufficient condition for the presence of systematic errors in environmental pressure estimates. We suggest two ways to leverage the additional explanatory power of multi-unit inventory tables to reduce instances of imbalances and aggregation biases. [ABSTRACT FROM AUTHOR]

This study presents the life cycle assessment (LCA) of three batteries for plug-in hybrid and full performance battery electric vehicles. A transparent life cycle inventory (LCI) was compiled in a component-wise manner for nickel metal hydride (NiMH), nickel cobalt manganese lithium-ion (NCM), and iron phosphate lithium-ion (LFP) batteries. The battery systems were investigated with a functional unit based on energy storage, and environmental impacts were analyzed using midpoint indicators. On a per-storage basis, the NiMH technology was found to have the highest environmental impact, followed by NCM and then LFP, for all categories considered except ozone depletion potential. We found higher life cycle global warming emissions than have been previously reported. Detailed contribution and structural path analyses allowed for the identification of the different processes and value-chains most directly responsible for these emissions. This article contributes a public and detailed inventory, which can be easily be adapted to any powertrain, along with readily usable environmental performance assessments. [ABSTRACT FROM AUTHOR]

The authors offer a commentary on the study "The Significance of Li-ion Batteries in Electric Vehicle Life-Cycle Energy and Emissions and Recycling's Role in its Reduction" by J. B. Dunn and colleagues, published in a previous issue. The commentary discusses the article's presentation of industry data, the modelling of energy intensity as a function of facility throughput, and their conclusion on the importance of facility throughput in resolving the energy debate.