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Techno-economic analysis and environmental assessment of isobutene, sustainable aviation fuel, omega-3 and omega-6 oils, and sophorolipid production in integrated sugarcane biorefineries
Thesis (MEng)--Stellenbosch University, 2026.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867613786747174912 |
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| access_status_str | Open Access |
| author | Adua, Bright |
| author2 | Gorgens, Johann Ferdinand |
| author_browse | Adua, Bright Gorgens, Johann Ferdinand |
| author_facet | Gorgens, Johann Ferdinand Adua, Bright |
| author_sort | Adua, Bright |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/135542 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:41:41.074Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/135542 Techno-economic analysis and environmental assessment of isobutene, sustainable aviation fuel, omega-3 and omega-6 oils, and sophorolipid production in integrated sugarcane biorefineries Adua, Bright Gorgens, Johann Ferdinand Louw, Janus Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Thesis (MEng)--Stellenbosch University, 2026. Adua, B. 2026. Techno-economic analysis and environmental assessment of isobutene, sustainable aviation fuel, omega-3 and omega-6 oils, and sophorolipid production in integrated sugarcane biorefineries. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/24bc1bee-9006-4577-94ec-7c80db491e2e The South African sugar industry faces numerous problems, including a decrease in local sugar demand and the exporting of surplus sugar at low and fluctuating international prices. Within this context, integration of biorefineries to produce high value bioproducts, thereby diversifying revenue streams, has been proposed to alleviate effects of these challenges. Sugarcane materials such as molasses, bagasse, and sugarcane harvest residues could be used to produce an array of products, including sorbitol, adipic acid, omega oils, and others. This study investigated several bioproducts for integration into a sugarcane biorefinery, including isobutene (IBN) and sustainable aviation fuel (SAF) derived from it, omega-3 oils (docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)), omega-6 oil (arachidonic acid (ARA)), and biosurfactants (sophorolipids (SL)). Process simulations were developed for each biorefinery scenario, primarily using A-molasses as first-generation (1G) feedstock, while a combination of A-molasses with sugarcane bagasse and harvest residues (1G2G) was considered for the IBN and SAF production, due to the ability of the microorganism to utilize pentose sugars. Economic viability was determined through a discounted cash flow rate of return analysis to calculate minimum selling prices (MSPs) for an acceptable return on investment, which were compared to prevailing market prices. Life cycle assessment (LCA) was utilized to evaluate the environmental benefits of each product and its associated biorefinery scenario, with a primary focus on global warming potential (GWP). The combined economic and environmental performance was used to determine the viability of each biorefinery as an investment opportunity for diversification in a sugarcane mill. Both 1G and 1G2G IBN scenarios were considered viable and attractive biorefinery options, with low carbon footprints and competitive economics. The low carbon footprint and competitiveness were mainly due to the simple, low-energy recovery of IBN as a volatile product in the fermentation off gas. The MSPs for 1G IBN and 1G2G IBN were 15.92% and 6.47% higher than the market price, respectively, which is well within acceptable green premiums of 20% - 60% for biobased products. The GWPs of 1G IBN and 1G2G IBN were 12.80% and 47.20% lower than their fossil-based counterpart. Similarly, the 1G2G SAF scenario was deemed a viable biorefinery option, achieving an MSP that was 105.56% higher than the market price, which falls well within the acceptable range for biobased aviation fuel (four to five times the price of conventional jet fuel), and a GWP that was 72.96% lower than its fossil-based counterpart. 1G2G SAF production through IBN demonstrated strong economic performance compared to other Alcohol-to-Jet (AtJ) pathways, such as bioethanol or isobutanol, due to the low production cost, low energy demands associated with IBN purification, and a more efficient oligomerization process. In comparison, the MSP of 1G2G IBN ($1.90/L) is at the low end of the range of $1.87 to 2.05/L reported in literature for ATJ using A-molasses. Unfortunately, the volatile and explosive nature of IBN also brings a significant fire risk for industrial facilities, which remains as the greatest stumbling block to industrial implementation of the technology. In the omega oil scenarios, 1G DHA and 1G ARA, exhibited marginally higher carbon footprints than their fish oil counterpart with GWPs that were 6.14% and 15.2% higher, respectively. However, both showed strong economic performance with MSPs 79.26 % and 80.45% lower than their respective market prices sourced from fish oil. The EPA scenario was the most high-performance biorefinery scenario, demonstrating strong economic and environmental advantages, with an MSP 88.31% lower than the market price and a 27.73% lower GWP compared to its fish oil counterpart. 1G DHA and 1G EPA were deemed to oversupply the market. At 10% of the market demand, the MSPs of 1G DHA and 1G EPA were 69.71% and 76.71% lower than their respective market prices. These results suggest that all the omega oil scenarios represent viable and attractive biorefinery options, primarily due to attractive market prices compared to production costs. For the sophorolipid scenarios, 1G SL-1, where A-molasses was supplemented with bought-in oleic acid as additional carbon source, was the preferred biorefinery option compared to 1G SL-2 (A-molasses-only scenario), mainly due to the synergistic benefits of the two carbon sources resulting in a disproportionately higher yield. The MSPs for 1G SL-1 and 1G SL-2 were 31.33% and 281.33% higher than the market prices of their fossil-fuel derived equivalents, respectively, and these scenarios were financially the least viable of all the scenarios considered. Both scenarios were deemed to oversupply the market. At 10% of the market demand, MSPs of 1G SL-1 and 1G SL-2 were 159.67% and 392% higher than the SL-market price, further affirming that these scenarios were the least financially viable. 1G SL-1 achieved a significantly lower GWP (70.69% lower) than its current fossil-based equivalent, while 1G SL-2 exhibited a 30.34% higher GWP. Despite the increased operational cost and environmental footprint associated with externally-sourced and expensive oleic acid, scenario 1G SL-1 demonstrated substantially improved financial and environmental benefits compared to 1G SL-2, due to the disproportionate improvements in yield, volumetric productivity and product titre associated with oleic acid supplementation. Overall, 1G EPA, 1G DHA, 1G ARA, 1G IBN, 1G2G IBN, and 1G2G SAF scenarios were all considered promising biorefinery options when benchmarked against alternative biorefinery products prioritized in prior studies, including sorbitol, monomeric lactic acid, isobutanol, and acrylic acid, positioning them as promising candidates for commercial deployment within sugarcane-based biorefineries. Masters 2026-04-01T08:52:31Z 2026-04-01T08:52:31Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/135542 en Stellenbosch University 188 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Adua, Bright Techno-economic analysis and environmental assessment of isobutene, sustainable aviation fuel, omega-3 and omega-6 oils, and sophorolipid production in integrated sugarcane biorefineries |
| title | Techno-economic analysis and environmental assessment of isobutene, sustainable aviation fuel, omega-3 and omega-6 oils, and sophorolipid production in integrated sugarcane biorefineries |
| title_full | Techno-economic analysis and environmental assessment of isobutene, sustainable aviation fuel, omega-3 and omega-6 oils, and sophorolipid production in integrated sugarcane biorefineries |
| title_fullStr | Techno-economic analysis and environmental assessment of isobutene, sustainable aviation fuel, omega-3 and omega-6 oils, and sophorolipid production in integrated sugarcane biorefineries |
| title_full_unstemmed | Techno-economic analysis and environmental assessment of isobutene, sustainable aviation fuel, omega-3 and omega-6 oils, and sophorolipid production in integrated sugarcane biorefineries |
| title_short | Techno-economic analysis and environmental assessment of isobutene, sustainable aviation fuel, omega-3 and omega-6 oils, and sophorolipid production in integrated sugarcane biorefineries |
| title_sort | techno economic analysis and environmental assessment of isobutene sustainable aviation fuel omega 3 and omega 6 oils and sophorolipid production in integrated sugarcane biorefineries |
| url | https://scholar.sun.ac.za/handle/10019.1/135542 |
| work_keys_str_mv | AT aduabright technoeconomicanalysisandenvironmentalassessmentofisobutenesustainableaviationfuelomega3andomega6oilsandsophorolipidproductioninintegratedsugarcanebiorefineries |