Coproducts of algae and yeast-derived single cell oils: A critical review of their role in improving biorefinery sustainability

•The economic and environmental implications of co-products from an SCO biorefinery were reviewed.•Protein component crucial factor determining economic and environmental impact.•Bulk lipid production should not be coupled with high value products.•Market analysis, LCA and TEA are crucial to bioprocessing scale-up. Oleaginous microalgae and yeast are of increasing interest as a renewable resource for single cell oils (SCOs). These have applications in fuels, feed and food products. In order to become cost competitive with existing terrestrial oils, a biorefinery approach is often taken where several product streams are valorised alongside the SCO. Whilst many life cycle assessment (LCA) and Techno-economic (TEA) studies have employed this biorefinery approach to SCO production, a systematic analysis of their implications is missing. This review evaluates the economic and environmental impacts associated with the use of coproducts. Overall, protein production plays the greatest role in determining viability, with coproduct strategy crucial to considering in the early stages of research and development.