Submitted to: Journal of Surfactants and Detergents
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2013
Publication Date: 4/16/2013
Citation: Ashby, R.D., Mcaloon, A.J., Solaiman, D., Yee, W.C., Reed, M.L. 2013. A process model for approximating the production costs of the fermentative synthesis of sophorolipids. Journal of Surfactants and Detergents. 16:683-691.
Interpretive Summary: Surfactants have been used for years in laundry, dishwashing detergents, and personal care products such as bubble baths, body washes, hand soaps, shaving products, shampoos and oral care products. Surfactants currently in use are chemically produced from petroleum-based materials, prices tend to fluctuate based on finite oil reserves and increasing and unstable oil prices. Within the last 10 years focus has shifted to the use of renewable materials to produce new bio-based surfactants with chemical properties that approximate petroleum-based equivalents. Sophorolipids are a class of bio-based surfactant that has been produced in large yields by fermentation and is beginning to find a number of potential applications; however, the cost to produce sophorolipids via fermentation has generally been assumed to be prohibitive compared to petroleum-based surfactants. In this paper we developed a flexible process economic model to approximate the cost to produce sophorolipids from glucose and a vegetable oil (high oleic sunflower oil) and an organic acid (oleic acid). In the model it was found that sophorolipids could be produced at a cost of US$1.34 per pound from glucose and high oleic sunflower oil and at a cost of US$1.15 per pound from glucose and oleic acid. These values are slightly higher than the current production costs of many petroleum-based surfactants, but as oil prices continue to fluctuate, new applications are developed and focus continues to shift towards environmental awareness, more opportunities will be developed for sophorolipid biosurfactants. Having this flexible model will allow future work to be better focused on cost reduction resulting in improved application potential.
Technical Abstract: Sophorolipids are microbial glycolipids that possess surfactant-type properties and have been successfully tested in a number of potential industrial and niche applications but they are generally acknowledged to require higher production costs when compared to petroleum-based surfactants. The objective of this study was to develop a process economic model for the fermentative synthesis of sophorolipids using contemporary process simulation software and current reagent, equipment, and supply costs, following current production practices. Glucose (Glc) and either high oleic sunflower oil (HOSO) or oleic acid (OA) were used as feedstocks and the annual production capacity of the plant was set at 90.7 million kg/yr with continuous operation of 24 h a day for 330 days per year. Facility construction costs and major equipment specification were calculated to be US$17.1 million but other considerations such as capital, labor, material and utilities costs were also included. The single greatest contributor to the overall production/operating cost was the cost of raw materials, which accounted for 89% and 87% of the total estimated production expenditures for the HOSO and oleic acid-based fermentations, respectively. Based on this model and assuming yields of 100 g/L, the cost of large-scale sophorolipid synthesis via fermentation from Glc:HOSO was calculated to be US$2.95/kg ($1.34/lb) and from Glc:OA to be US$2.54/kg ($1.15/lb). The model is flexible and can be adjusted to reflect changes in capital, production and feedstock costs as well as changes in the type of feedstocks used.