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Background: Microbial oils – often termed single cell oils (SCOs) – offer an alternative to terrestrial oil crops across the energy, food and chemical industries. In addition to oils, a range of secondary metabolites can be produced from the heterotrophic organisms as part of a biorefinery system. Techno‐economic analysis (TEA) is an important tool for evaluating economic viability, and although TEA is subject to high uncertainties where production is still at the laboratory scale, the tool can play a significant role in directing further research to evaluate suitability of scale‐up. Results: SCO production from the oleaginous yeast Metschnikowia pulcherrima using sucrose, wheat straw and distillery waste feedstocks was evaluated at two production scales. At a scale of 100 t year−1 oil production a minimum estimated selling price (MESP) of €14 000 t–1 was determined for sucrose. This reduced to €4–8000 t–1 on scaling to 10 000 t year−1, with sucrose and wheat straw yielding the lowest MESP. Conclusions: Feedstock price and lipid yield had the greatest impact on overall economic return, though the valorization of co‐products also had a large effect, and further play between feedstock and system productivity strategies could bring the price down to be competitive with terrestrial oils in the future. The novel approach demonstrated here for the first time integrates uncertainty into economic analysis whilst facilitating decision‐support at an early technology development stage. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

There is an increasing interest in the replacement of traditional plant based glyceride oils with microbial oils for fuel, food, dietary supplements and other pharmaceuticals and chemicals. To understand the environmental implications of this technology a systems approach is required. To date the majority of Life Cycle Assessment (LCA) studies have addressed the use of photoautotrophic (light stimulated growth, atmospheric carbon fixing) microbes to produce biofuels. But, with an increasing number of biotechnology companies using heterotrophic (non-light stimulated growth, requiring an organic carbon feedstock) microbes for large-scale industrial food and consumer goods production processes, it is important that the environmental implications of heterotrophic technology for products outside of the energy sector are better understood. This review assesses the current life cycle literature available that relates to heterotrophic algae and yeast microbial oil production, evaluating where current gaps in knowledge and uncertainties lie. It also includes relevant LCA information from other production processes. Overall, the review finds significant gaps relating to both life cycle inventory and impact assessment information. Improved industrial data sets are needed, particularly for novel feedstocks, and cultivation and downstream processing towards non-fuel products. The implications of synthetic biology also need to be addressed. Impact assessment does not currently include a broad range of impact categories, focusing predominately on energy use and climate change. And to answer wider implications questions, further LCA studies are needed that take a more consequential approach. Addressing these areas is vital to ensure commercial viability, sustainability and public acceptance of the technology going forward. [ABSTRACT FROM AUTHOR]

• 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. [ABSTRACT FROM AUTHOR]