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The increasing consumption of animal-based proteins causes substantial environmental impacts, necessitating a shift towards alternative proteins. Seaweed-based proteins offer a promising solution, with several studies suggesting low environmental impacts and valuable nutritional properties. This paper conducts a literature review on seaweed-based proteins, aiming to summarize the current knowledge on their environmental impacts while deriving recommendations for future LCA studies. Following a two-tier approach, a broad literature sample of 139 studies was identified to summarize relevant value chains, while fourteen key LCA studies were analyzed in more detail, also considering methodological choices and impact assessment results. The study proposes a harmonized value chain framework that facilitates comparison across studies, revealing heterogeneity in the investigated value chains regarding cultivation, processing technologies, and seaweed types. Gaps exist for green and red seaweed, novel extraction technologies and downstream steps, such as product formulation and use phase. Some methodological shortcomings are evident, particularly in addressing multifunctionality, marine biodiversity impacts and product functionality. Across all studies, transparency in methodological choices and the system description could be improved. The synthesis of impact assessment results suggests that seaweed-based proteins exhibit lower environmental impacts than animal-based proteins: when assessed considering protein content, climate impact can be reduced by between 30 % and 100 % compared to poultry. Based on these insights, the review names underrepresented value chains to be prioritized in future studies. Guidance is given on selecting system boundaries, functional units, and multifunctionality approaches in line with study objectives as well as options for incorporating marine biodiversity into LCA.
Schelte et al. (Wed,) studied this question.