Critical indicators of sustainability for biofuels: An analysis through a life cycle sustainabilty assessment perspective

The reduction of anthropogenic greenhouse gas emissions to mitigate climate change poses challenges across multiple sectors. Biofuels have been touted as a replacement for petroleum-based fuels, but policy guiding this sector must ensure that biomass is obtained in a sustainably. In this context, Life Cycle Sustainability Assessment (LCSA) tools have been identified as a means to conduct comprehensive impact evaluations of the biofuel sector. The objective of this work is to highlight key environmental, economic, and social indicators currently being assessed using LCSA, and to relate these back to the framework of Principles and Criteria (P&C) developed by the Roundtable on Sustainable Biomaterials (RSB) to assess the ability of LCSA approaches to effectively inform all Principles within the RSB. 60 LCSA studies, published since 2007, were selected to include a range of biofuel production scenarios, including various technologies and geographic settings. System boundaries and functional units used in these studies were evaluated and compared. The ability of each study to provide quantitative indicators related to environmental, economic, and social sustainability was tabulated. It was found that some RSB Principles can be effectively evaluated using an LCSA approach, including Principle 3 (greenhouse gas emissions) and Principle 10 (air quality). Most other Principles within the RSB P&C framework, however, are only partially addressed, and Principle 11 (technology, inputs, and management of waste) is not informed in any way by existing LCSA. The results suggest that existing LCSA studies, while expanding to consider more economic and social sustainability considerations, are unlikely to cover all aspects of biofuel production systems and are not sufficient to completely inform the full range of RSB Criteria. In the future, LCSA should be further extended to help address critical aspects of sustainability, while the RSB framework should be strengthened to employ a life cycle approach across all Principles.