Browsing by Author "van Heerden, Cara"
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- ItemTechno-economic analysis of 1,3-propanediol, sorbitol, itaconic acid, and xylooligosaccharides production from sugarcane-based feedstocks(Stellenbosch : Stellenbosch University, 2023-03) van Heerden, Cara; Görgens, Johann Ferdinand; Farzad, Somayeh; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH ABSTRACT: In an effort to reduce the human impact on the environment and reduce our reliance on finite fossilbased resources, the need for cost-competitive bioproducts is increasing. One of the potential feedstocks for the establishment of a successful green economy is sugarcane. The South African sugar industry is facing several economic challenges that can be lessened by adding an annexed biorefinery producing high-value bio-products to existing sugarcane mills, to diversify their revenue streams. Both first generation (1G) (molasses) and second generation (2G) (bagasse and trash) feedstock can be used in a biorefinery. This project aimed to evaluate the feasibility of a biorefinery annexed to a South African sugar mill, based on a selection of potential products. Four different bio-products were considered for production from sugarcane-based feedstocks. 1,3- Propanediol (PDO) is a useful building block used in producing the popular textile iiolytrimethylene terephthalate. It can be used as a precursor in polyurethane production among several other uses. Xylooligosaccharides (XOS) is an emerging prebiotic with the outlook of giving value to the hemicellulose portion of lignocellulose. Sorbitol is a well-known sugar alcohol predominantly used in the food industry and for vitamin-C production with the potential of replacing several fossil-based chemical products. Itaconic acid (IA) can become an important commodity biochemical with applications in several polymers, detergent builders, and surfactants if the market price of this product can become competitive with its fossil-based equivalents. These selected 4 products were assessed for economic and environmental feasibility in their own right, together with comparison to alternative products reported elsewhere. Following the development of the process scenarios from literature, the economic feasibility of the scenarios was evaluated using discounted cash flow sheets. PDO production from 1G, 1G2G, and crude glycerol was compared. It was found that a direct fermentation strategy utilising 1G feedstock had the lowest energy and capital investment costs. Consequently, it was the most profitable PDO scenario with an internal rate of return (IRR) of 75.36%. XOS production was found to have the highest IRR of all the investigated scenarios at 87.94%. However, despite having a lower IRR of 77.73%, PDO and XOS co-production better utilized the available 1G and 2G feedstock and would likely be a safer investment. Sorbitol production with green hydrogen resulted in one feasible scenario for the 1G sorbitol and mannitol co-production, while two other scenarios were found to have an IRR within 2% of the preferred IRR of 20%. The low market price and energy-intensive fermentation process for IA production led to unfeasible IA scenarios. The environmental performance of investigated scenarios has been compared by determining their greenhouse gas (GHG) emissions with a GHG calculator tool. Sorbitol production, direct PDO production, PDO and XOS co-production, and 1G IA production were found to have low GHG emissions while indirect PDO production, XOS production, and 1G2G IA production had high GHG emissions. Two scenarios, direct PDO production and PDO and XOS co-production from 1G2G feedstock were consequently identified as biorefinery scenarios that will both have economic and environmental benefits and are therefore recommended as possibly feasible biorefinery scenarios.