Search

PurposeBioenergy is increasingly used to help meet greenhouse gas (GHG) and renewable energy targets. However, bioenergy's sustainability has been questioned, resulting in increasing use of life cycle assessment (LCA). Bioenergy systems are global and complex, and market forces can result in significant changes, relevant to LCA and policy. The goal of this paper is to illustrate the complexities associated with LCA, with particular focus on bioenergy and associated policy development, so that its use can more effectively inform policymakers.MethodsThe review is based on the results from a series of workshops focused on bioenergy life cycle assessment. Expert submissions were compiled and categorized within the first two workshops. Over 100 issues emerged. Accounting for redundancies and close similarities in the list, this reduced to around 60 challenges, many of which are deeply interrelated. Some of these issues were then explored further at a policy-facing workshop in London, UK. The authors applied a rigorous approach to categorize the challenges identified to be at the intersection of biofuels/bioenergy LCA and policy.Results and discussionThe credibility of LCA is core to its use in policy. Even LCAs that comply with ISO standards and policy and regulatory instruments leave a great deal of scope for interpretation and flexibility. Within the bioenergy sector, this has led to frustration and at times a lack of obvious direction. This paper identifies the main challenge clusters: overarching issues, application and practice and value and ethical judgments. Many of these are reflective of the transition from application of LCA to assess individual products or systems to the wider approach that is becoming more common. Uncertainty in impact assessment strongly influences planning and compliance due to challenges in assigning accountability, and communicating the inherent complexity and uncertainty within bioenergy is becoming of greater importance.ConclusionsThe emergence of LCA in bioenergy governance is particularly significant because other sectors are likely to transition to similar governance models. LCA is being stretched to accommodate complex and broad policy-relevant questions, seeking to incorporate externalities that have major implications for long-term sustainability. As policy increasingly relies on LCA, the strains placed on the methodology are becoming both clearer and impedimentary. The implications for energy policy, and in particular bioenergy, are large.

Background: Microbial oils – often termed single cell oils (SCOs) – offer an alternative to terrestrial oil crops across the energy, food and chemical industries. In addition to oils, a range of secondary metabolites can be produced from the heterotrophic organisms as part of a biorefinery system. Techno‐economic analysis (TEA) is an important tool for evaluating economic viability, and although TEA is subject to high uncertainties where production is still at the laboratory scale, the tool can play a significant role in directing further research to evaluate suitability of scale‐up. Results: SCO production from the oleaginous yeast Metschnikowia pulcherrima using sucrose, wheat straw and distillery waste feedstocks was evaluated at two production scales. At a scale of 100 t year−1 oil production a minimum estimated selling price (MESP) of €14 000 t–1 was determined for sucrose. This reduced to €4–8000 t–1 on scaling to 10 000 t year−1, with sucrose and wheat straw yielding the lowest MESP. Conclusions: Feedstock price and lipid yield had the greatest impact on overall economic return, though the valorization of co‐products also had a large effect, and further play between feedstock and system productivity strategies could bring the price down to be competitive with terrestrial oils in the future. The novel approach demonstrated here for the first time integrates uncertainty into economic analysis whilst facilitating decision‐support at an early technology development stage. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

LCA has evolved from its origins in energy analysis in the 1960s and 70s into a wide ranging tool used to determine impacts of products or systems over several environmental and resource issues. The approach has become more prevalent in research, industry and policy. Its use continues to expand as it seeks to encompass impacts as diverse as resource accounting and social well being. Carbon policy for bioenergy has driven many of these changes. Enabling assessment of complex issues over a life cycle basis is beneficial, but the process is sometimes difficult. LCA's use in framing is increasingly complex and more uncertain, and in some cases, irreconcilable. The charged environment surrounding biofuels and bioenergy exacerbates all of these. Reaching its full potential to help guide difficult policy discussions and emerging research involves successfully managing LCA's transition from attributional to consequential and from retrospective to prospective. This paper examines LCA's on-going evolution and its use within bioenergy deployment. The management of methodological growth in the context of the unique challenges associated with bioenergy and biofuels is explored. Changes seen in bioenergy LCA will bleed into other LCA arenas, especially where it is important that a sustainable solution is chosen. [ABSTRACT FROM AUTHOR]