Evaluating microalgae-to-energy -systems: different approaches to life cycle assessment (LCA) studies

Life cycle assessment (LCA) is a valuable tool for determining the environmental impacts associated with different products and has been widely used to assess biofuel production. As a scientific methodology rather than a standardized test, every LCA may be thought of as unique in terms of the selection of functional units or determination of system boundaries. Researchers generally tailor the method to meet the specific goals of their own investigations. This review examines a number of LCAs used to evaluate microalgae-to-energy systems, and evaluates their contributions in terms of their ability to support commercialization efforts in this sector. To this end, a new scoring system for LCAs is proposed based on input/output flows, data origin, production technologies and system boundaries, selection of assumptions and variables, as well as the ability to track environmental, economic, and social impacts. The review suggests that, while a wide variety of new technological pathways for microalgae-to-energy systems are being assessed, the majority of studies reported employ relatively limited system boundaries that may not capture the full impacts of the processes. The number of environmental impact factors being tracked is limited, and many studies do not consider important impacts such as water or land use. Most studies do not incorporate critical information about economics related to new process configurations, which will be essential to support commercialization efforts in this area. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd