Techno‐economic analysis (TEA) of microbial oil production from waste resources as part of a biorefinery concept: assessment at multiple scales under uncertainty

Abstract

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.(2) Discounted cash flow analysis was used to obtain a minimum estimated selling price (MESP) based on a net present value (NPV) J Chem Technol Biotechnol 2019; 94: 701-711

The role of temperature, pH and nutrition in process development of the unique oleaginous yeast Metschnikowia pulcherrima

“…) is contrary to what has been observed with native M. pulcherrima , where lipid accumulation was enhanced at lower cultivation temperatures . Potential reasons for this are that the strain used in this study was evolved at 25 °C, but also that the fermentation took place under controlled oxygen (DO 50%) and pH (pH 4) rather than in shake flasks with limited process parameter control. In this respect, it has been shown that native M. pulcherrima achieves far higher lipid contents in STRs, presumably due to the higher oxygen availability, which is not the case with the evolved strain .…”

“…Research has driven the technology forward in the last century, but compelling data on the effect of basic process parameters such as temperature, pH and nutrition on yeast lipid production, foremost its kinetics, is, especially in relation to the wide range of oleaginous yeasts, 2 remarkably rare. Enhanced lipid production kinetics are a crucial factor for commercial deployment of yeast lipid technology, 3,4 and it is surprising that acquisition of corresponding data is often omitted in process development. 5 Among the known oleaginous yeasts, the majority are cultured around 30°C with the higher temperatures generally leading to advanced reaction kinetics.…”

Achieving a high‐density oleaginous yeast culture: Comparison of four processing strategies using Metschnikowia pulcherrima

“…To meet the growing demand for terrestrial oils, oleaginous microorganisms offer a promising alternative. These microbes are generally defined as producing over 20% (w/w) lipids (Thorpe & Ratledge, ), though the cost associated with the bulk production of those single cell oils are still too high for commercial viability (Koutinas, Chatzifragkou, Kopsahelis, Papanikolaou, & Kookos, ; Parsons, Abeln, McManus, & Chuck, ).…”

“…However, the key issue with M. pulcherrima is its relatively slow growth cycle (Abeln et al, ; Chantasuban et al, ; Li, Zhao, & Bai, ; Pan, Kwak, & Rhee, ; Santomauro et al, ; Zhang et al, ; Zhao, Hu, Wu, Shen, & Zhao, ): partly contingent upon a relatively low cultivation temperature promoting lipid synthesis (Santomauro et al, ), lipid productivities of up to only 0.05 g L −1 h −1 are reported in batch fermentation (Abeln et al, ). To yet facilitate economically feasible cultivation, the space‐time yield requires improvement (Koutinas et al, ; Parsons et al, ). One promising approach could be the cultivation at high cell densities, which is proposed to facilitate higher rates of reaction, assuredly reduces reactor volume, and facilitates downstream processing (Bunch, ).…”

Characterization of threeYarrowia lipolyticastrains in respect to different cultivation temperatures and metabolite secretion

“…Although traditional oil crops are still the main source for renewable oil, microbes gain in importance, as they have shorter life cycle, do not dependent on arable land and do not necessarily compete with human or animal food production. Nonetheless, the high processing costs constitute a major barrier for an economically viable large-scale production of microbial oil (Braunwald et al 2014;Parsons et al 2018) .…”