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Retrofitting a typical South African sugar mill to co-produce a range of alternative sweeteners: a stochastic techno-economic study
Thesis (MEng)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613992665481216 |
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| access_status_str | Open Access |
| author | Amanful, Bright |
| author2 | Görgens, Johann Ferdinand |
| author_browse | Amanful, Bright Görgens, Johann Ferdinand |
| author_facet | Görgens, Johann Ferdinand Amanful, Bright |
| author_sort | Amanful, Bright |
| collection | Thesis |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127226 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:44:57.544Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127226 Retrofitting a typical South African sugar mill to co-produce a range of alternative sweeteners: a stochastic techno-economic study Amanful, Bright Görgens, Johann Ferdinand Dogbe, Eunice Sefakor Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. Stochastic analysis -- Economic aspects -- South Africa Thaumatins -- Biotechnology Sugar trade -- South Africa Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: An alternative to the current trend of maximizing sugar recovery in a three-stage sugar crystallization process, is the diversion of A-molasses into an annexed biorefinery to produce alternative sweeteners. This is aimed at improving the value chain of the South African sugar industry and has become necessary due to cost and market challenges that make maximum sugar recovery unprofitable. Among the many challenges are the rising cost of sugar production, decreasing demand for sugar, plummeting prices of sugar on the global sugar market and the implementation of sugar tax, which consequentially limits the industry's ability to operate profitably and sustainably. Isomaltulose, allulose, short chain fructooligosaccharides (scFOS), and thaumatin are alternative sweeteners known to have similar physical and organoleptic properties to sucrose. These are recognized as safe, have growth trajectories and market demands, and are widely utilized in the food, beverage, and pharmaceutical industries. Amolasses is considered a low-cost feedstock, suitable for the bioproduction of these high-value sweeteners, in support of the long-term objective to create a more diversified, cost-effective, and competitive industry. Single product and multiproduct scenarios for the bioproduction of the sweeteners were simulated in Aspen Plus® and techno-economic analysis was performed for each scenario. In the case of the single product scenarios, the available 25.43 tons/h of Amolasses from a typical South African sugar mill resulted in product throughputs representing 38%, 28%, 95%, and Two multiproduct scenarios were developed for the co-production of isomaltulose, allulose and scFOS in a single facility, using either six bioreactors or a single bioreactor. Such a facility could utilize all the available A-molasses to produce less than 15% of the global market for each of the three products, thereby substantially reducing the risk of market oversupply. Deterministic economic analysis resulted in an IRR of 50% and payback period of 3.01 years for the six-bioreactor scenario, while the single bioreactor scenario achieved an IRR of 60% and payback period of 2.80 years. Stochastic Monte Carlo analysis was applied to quantify the financial risks of these investments, considering historical price and CAPEX variabilities, demonstrating a mean IRR of 41% for the one-bioreactor scenario, and a 36% IRR for the six-bioreactor scenario. While the stochastically determined IRRs affirm the superficiality of the deterministically determined profitability, a 100% probability that the stochastic IRRs exceed 20% indicates a risk-averse portfolio. Moreover, the stochastic IRRs were higher than other products considered for sugarcane diversification, further demonstrating the benefits of combining products with attractive market prices in a single facility. By considering mixed product campaigns (MPC) and non-integer batch formulations, it was possible to schedule a single shared bioreactor system for the manufacture of all three products to exploit the economies-of-scale benefits compared to the use of six smaller bioreactors. For the MPC scheduling, batches of the various products were repeated in four time periods over the time horizon thereby allowing the overall product demand to be satisfied under a reduced make span objective. AFRIKAANS OPSOMMING: ’n Alternatief tot die huidige tendens van maksimering van suikerherwinning in ’n driefase suikerkristallisasieproses, is die wegwending van A-molasse in ’n geannekseerde bioraffinadery om alternatiewe versoeters te produseer. Hierdie sal beoog om die finansiële lewensvatbaarheid of waardeketting van die Suid-Afrikaanse suikerindustrie te verbeter en het nodig geword as gevolg van koste- en markuitdagings wat maksimum suikerherwinning nie-winsgewend gemaak het. Onder die vele uitdagings is die stygende koste van suikerproduksie, verminderde aanvraag vir suiker, vallende pryse van suiker op die globale suikermark en die implementasie van suikerbelasting, wat vervolgens die industrie se vermoë beperk om winsgewend en volhoubaar bedryf te word. Isomaltulose, allulose, kortketting-fruktoöligosakkariedes (scFOS) en toumatien is alternatiewe versoeters bekend om soortgelyke fisiese en organoleptiese eienskappe as sukrose te hê. Hierdie word oor die algemeen herken as veilig, het positiewe groeibane en markaanvraag, en word algemeen in kos, drankie en farmaseutiese industrieë gebruik. A-molasse word beskou as lae-koste voermateriaal, gepas vir die bioproduksie van die hoë-waarde versoeters, in ondersteuning van die lang-termyn doelwit om ’n meer gediversifiseerde, koste-effektiewe en kompeterende industrie te skep. Enkelproduk en multiproduk scenario’s vir die bioproduksie van die versoeters is gesimuleer in AspenPlus® en tegnoëkonomiese analise is uitgevoer vir elke scenario. In die geval van die enkelprodukscenario’s, het die beskikbare 25.433 ton/h A-molasse van ’n tipiese Suid-Afrikaanse suikermeule gelei na produkdeursette wat 38%, 28%, 95% en <1% van die globale produksietempo’s van isomaltulose, allulose, ortkettingfruktoöligosakkariedes en toumatien, onderskeidelik, wat beduidende risiko van markvloeding met die produk verteenwoordig het. By die gewenste 20% interne opbrengskoers (IRR; reële terme), was die minimum verkoopsprys (MSP) vir die enkelprodukte 870 $/ton vir isomaltulose, 2 030 $/ton vir allulose, 1 540 $/ton vir scFOS en 11 665 000 $/ton vir toumatien, wat onder die onderskeidelike markpryse vir die eerste drie produkte was. Toumatien se bioproduksie deur Komagataella (Pichia) pastoris was nie-winsgewend as gevolg van die relatiewe lae-gerapporteerde opbrengste (30 mg/L); toumatien se bioproduksie mag ekonomies lewensvatbaar wees vanaf konsentrasies bo 300 mg/L. Twee multiprodukscenario’s is ontwikkel vir die ko-produksie van isomaltulose, allulose en scFOS in ’n enkelfasiliteit, deur óf ses bioreaktors óf ’n enkel-bioreaktor te gebruik. So ’n fasiliteit kon al die beskikbare A-molasse gebruik om minder as 15% van die globale mark vir elk van die drie produkte te produseer, en daardeur die risiko om die mark oor te verskaf, grootliks te verminder. Deterministiese ekonomiese analise het geresulteer in ’n IRR van 50% en terugbetalingsperiode van 3.15 jaar vir die ses-bioreaktorscenario, terwyl die enkel-bioreaktorscenario ’n IRR van 60% en terugbetalingsperiode van 2.88 jaar het. Stochastiese Monte Carlo-analise is toegepas om die finansiële risiko’s van hierdie beleggings te kwantifiseer, met historiese prysveranderlikes in oorweging, wat ’n gemiddelde IRR van 41% vir die een-bioreaktorscenario, en ’n 36% IRR vir die sesbioreaktorscenario gedemonstreer het. Die IRRe bereik vir die multiprodukfasiliteit is beduidend hoër as ander produkte oorweeg vir suikerrietdiversifisering, wat verder die voordele van gesamentlike produkte met aanloklike markpryse in ’n enkelfasiliteit, demonstreer. Veldtog-gebaseerde skedulering vir die vervaardiging van al drie produkte deur ’n enkel, gedeelde bioreaktorsisteen te gebruik was daarom finansieel die meer robuuste opsie, deur die ekonomië-van-skaal voordele uit te buit, in vergelyking met ses kleiner bioreaktore. Masters 2023-03-03T11:52:40Z 2023-05-18T07:10:46Z 2023-03-03T11:52:40Z 2023-05-18T07:10:46Z 2023-03 Thesis http://hdl.handle.net/10019.1/127226 en_ZA en_ZA xv, 206 pages application/pdf Stellenbosch : Stellenbosch University Stellenbosch University |
| spellingShingle | Stochastic analysis -- Economic aspects -- South Africa Thaumatins -- Biotechnology Sugar trade -- South Africa Amanful, Bright Retrofitting a typical South African sugar mill to co-produce a range of alternative sweeteners: a stochastic techno-economic study |
| title | Retrofitting a typical South African sugar mill to co-produce a range of alternative sweeteners: a stochastic techno-economic study |
| title_full | Retrofitting a typical South African sugar mill to co-produce a range of alternative sweeteners: a stochastic techno-economic study |
| title_fullStr | Retrofitting a typical South African sugar mill to co-produce a range of alternative sweeteners: a stochastic techno-economic study |
| title_full_unstemmed | Retrofitting a typical South African sugar mill to co-produce a range of alternative sweeteners: a stochastic techno-economic study |
| title_short | Retrofitting a typical South African sugar mill to co-produce a range of alternative sweeteners: a stochastic techno-economic study |
| title_sort | retrofitting a typical south african sugar mill to co produce a range of alternative sweeteners a stochastic techno economic study |
| topic | Stochastic analysis -- Economic aspects -- South Africa Thaumatins -- Biotechnology Sugar trade -- South Africa |
| url | http://hdl.handle.net/10019.1/127226 |
| work_keys_str_mv | AT amanfulbright retrofittingatypicalsouthafricansugarmilltocoproducearangeofalternativesweetenersastochastictechnoeconomicstudy |