Life cycle assessment of biofuel production from brown seaweed in Nordic conditions

The use of algae for biofuel production is expected to play an important role in securing energy supply in the next decades. A consequential life cycle assessment (LCA) and an energy analysis of seaweed-based biofuel production were carried out in Nordic conditions to document and improve the sustainability of the process. Two scenarios were analyzed for the brown seaweed (Laminaria digitata), namely, biogas production (scenario 1) and bioethanol + biogas production (scenario 2). Potential environmental impact categories under investigation were Global Warming, Acidification and Terrestrial Eutrophication. The production of seaweed was identified to be the most energy intensive step. Scenario 1 showed better per- formance compared to scenario 2 for all impact categories, partly because of the energy intensive bioeth- anol separation process and the consequently lower overall efficiency of the system. For improved environmental performance, focus should be on optimization of seaweed production, bioethanol distilla- tion, and management of digestate on land.