(28c) Life Cycle Assessment of Biofuel and Bioenergy Production from Brown Algae through Biochemical Pathways

Authors: 
Fasahati, P., University of Wisconsin-Madison
Liu, J. J., Pukyong National University
Saffron, C. M., Michigan State University
Brown algae Laminaria Japonica is the most cultivated type of seaweed with a large potential for sustainable biofuel and bioenergy production. This study aims to evaluate the environmental impacts of seaweed cultivation and utilization for biofuel production through biochemical conversion routes including the sugar platform (SP), methane platform (MP), and volatile fatty acids platform (VFAP). In the SP, bioethanol is produced through saccharification of carbohydrates and fermentation of produced sugars. In the MP and VFAP, methane and volatile fatty acids (VFA) are produced through anaerobic digestion of seaweed. In the MP, methane is utilized as fuel source in a boiler/turbogenerator for heat and power production. In VFAP, VFAs are recovered through extraction/distillation and then hydrogenated to mixed alcohols. All three processes are simulated in Aspen Plus v.8.8 to obtain heat and material balances. Simulation results along with data from literature and Ecoinvent V3 databases for seaweed cultivation, chemicals, nutrients, and waste treatment operation are used to obtain life cycle inventory. Then, life cycle models are developed in SimaPro V8.2 software for each process. The environmental impact categories considered include global warming potential, acidification, eutrophication, fresh water consumption, and non-renewable energy use. Results are used to identify bottlenecks, limitations, and main contributors to the environmental profile of each route and assess the potentials to reduce the emissions and enhance the sustainability of the production process.