Integrating the Role of Thermodynamics in LCA: A Case Study of Microalgal Biofuels

Abstract

Liquid transportation fuels derived from biomass have gained considerable attention due to their potential to reduce the carbon intensity in the transportation sector and mitigate the effects of global climate change. As such, holistic assessment of the environmental impacts throughout the emerging biofuel supply chains is critical for determining the sustainability of emerging biofuel pathways. Systems analysis via life cycle assessment (LCA) has emerged as the prevalent methodological framework for quantifying the environmental impacts of biofuel systems. However, traditional LCA fails to account for the role of ecosystem goods and services in fuel and product life cycles. In addition, LCA and energy analysis suffers from several limitations such as ignoring the differences in the quality of the energy resource, assuming perfect substitutability of resources, and accounting for only the first law of thermodynamics. Thermodynamic based approaches that utilize exergy and emergy can address several limitations of traditional LCA. This chapter discusses the research progress and methodological advances in thermodynamic based methods for LCA and its application in assessing the environmental impacts of emerging microalgal biofuels. An analysis of microalgal biofuel production is considered as a case study, and the results of thermodynamic metrics are benchmarked against other life cycle based environmental sustainability metrics.