Browsing by Author "Klaver, Monique"

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    Techno-economic analysis of biorefinery scenarios for scFOS, ethanol, tryptophan, erythritol and collagen production from sugarcane
    (Stellenbosch : Stellenbosch University, 2023-12) Klaver, Monique; Görgens, Johann Ferdinand; Louw, Jeanne; Petersen, Abdul M.; Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering.
    ENGLISH ABSTRACT: The global sugarcane industry is under threat due to low international prices and oversupply of sucrose markets. In an effort to explore ways to alleviate this economic strain, this study explored different biorefinery integration scenarios. The economic and environmental sustainability of five potential products derived from sugarcane-based feedstock were evaluated: short-chain fructooligosaccharides (scFOS), ethanol, tryptophan, erythritol, and collagen. Nine biorefinery scenarios were investigated, including small-scale facilities that are decentralized and large-scale facilities that are annexed to an existing sugar mill. Each scenario was simulated in Aspen Plus® and a techno-economic analysis was conducted using the mass and energy balance data from the simulations. Additionally, greenhouse gas (GHG) emissions were assessed using the Roundtable on Sustainable Biofuels (RSB) tool. The small-scale implementation of biorefinery scenarios for production of scFOS alone and scFOS in combination with bio-ethanol were economically feasible, with minimum selling prices (MSPs) below their market prices. However, the large-scale production scenario of scFOS and/or ethanol, in biorefineries annexed to an existing sugar mill, provided better economics than small-scale facilities, despite a cheaper feedstock and the selection of simplified process technologies. However, small-scale production was the preferred investment option for scFOS-only production in a biorefinery, due to appropriate production rates for the size of the global market, to avoid oversupply. Simplified sugarcane processing to ethanol in small-scale facilities also lowered the product yield and increased capital costs. Furthermore, from the GHG analysis results, the large-scale scenarios consistently exhibited lower equivalent CO2 emissions per unit product compared to their small-scale counterparts, with the coproduction of scFOS and ethanol having the smallest emissions and greatest environmental benefit. Large-scale production of scFOS and/or ethanol in annexed biorefineries were compared to similar scenarios producing tryptophan, erythritol or collagen. Tryptophan demonstrated the highest profitability, with an MSP that was 59.7% of its market price. Despite this, the large-scale production of collagen was deemed more economically viable due to the avoidance of market oversupply. The largescale production of erythritol was unfruitful due to the low market price and high operational costs associated with this scenario. Moreover, the GHG analysis showed all scenarios to have low emissions, where the tryptophan production scenario was the most environmentally friendly option due to its low chemical and freshwater requirement. Among all the large-scale scenarios, only the production of ethanol and collagen were deemed viable market opportunities due to their favourable profitability and low market contribution. Despite the positive economic results of the other scenarios, their high market contribution (over 45%) led to their disqualification, as it would negatively affect product market prices. This comparison highlighted a trade-off between economic and environmental sustainability in biorefinery scenarios. While collagen production had a higher profitability than ethanol production, the latter had a more favourable environmental impact. In conclusion, it was recommended that the large-scale production of ethanol and collagen, as well as the small-scale production of scFOS be further considered for sugarcane diversification. The small-scale production of ethanol, co-production of scFOS and ethanol and the large-scale production of erythritol were eliminated as viable scenarios due to unfavourable economic and material balance results, while Stellenbosch University https://scholar.sun.ac.za iii the large-scale production of tryptophan could be considered viable at small-scale production. These findings can inform decisions regarding sustainable and environmentally responsible biorefinery strategies. Currently, they are being processed into low value fish meal, which is used as animal feed,