The use of algae for biofuelproduction is expected to play an important role in securing energy supply in the next decades. A consequential lifecycleassessment (LCA) and an energy analysis of seaweed-based biofuelproduction were carried out in Nordicconditions to document and improve the sustainability of the process. Two scenarios were analyzed for the brownseaweed (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 performance compared to scenario 2 for all impact categories, partly because of the energy intensive bioethanol separation process and the consequently lower overall efficiency of the system. For improved environmental performance, focus should be on optimization of seaweedproduction, bioethanol distillation, and management of digestate on land.