“…Steam explosion pretreatment, catalysed with sulphur dioxide (SO 2 ), along with simultaneous saccharification and co-fermentation (SScF) was adopted in the process model for ethanol production, based on the promising conversion performance demonstrated in previous studies [54–57]. To minimise enzyme supply costs [58], an on-site cellulase enzyme production unit was modelled in the biorefinery simulation, based on the literature data sourced from the National Renewable Energy Laboratory [59].…”
Section: Methodsmentioning
confidence: 99%
“…1) includes waste water treatment (WWT) and water cycle for CHP unit. In WWT, during anaerobic digestion biogas is produced and sent to CHP unit, while the treated water is recycled internally [57]. Fig.…”
BackgroundDriven by a range of sustainability challenges, e.g. climate change, resource depletion and expanding populations, a circular bioeconomy is emerging and expected to evolve progressively in the coming decades. South Africa along with other BRICS countries (Brazil, Russia, India and China) represents the emerging bioeconomy and contributes significantly to global sugar market. In our research, South Africa is used as a case study to demonstrate the sustainable design for the future biorefineries annexed to existing sugar industry. Detailed techno-economic evaluation and Life Cycle Assessment (LCA) were applied to model alternative routes for converting sugarcane residues (bagasse and trash) to selected biofuel and/or biochemicals (ethanol, ethanol and lactic acid, ethanol and furfural, butanol, methanol and Fischer–Tropsch synthesis, with co-production of surplus electricity) in an energy self-sufficient biorefinery system.ResultsEconomic assessment indicated that methanol synthesis with an internal rate of return (IRR) of 16.7% and ethanol–lactic acid co-production (20.5%) met the minimum investment criteria of 15%, while the latter had the lowest sensitivity to market price amongst all the scenarios. LCA results demonstrated that sugarcane cultivation was the most significant contributor to environmental impacts in all of the scenarios, other than the furfural production scenario in which a key step, a biphasic process with tetrahydrofuran solvent, had the most significant contribution.ConclusionOverall, the thermochemical routes presented environmental advantages over biochemical pathways on most of the impact categories, except for acidification and eutrophication. Of the investigated scenarios, furfural production delivered the inferior environmental performance, while methanol production performed best due to its low reagent consumption. The combined techno-economic and environmental assessments identified the performance-limiting steps in the 2G biorefinery design for sugarcane industry and highlighted the technology development opportunities under circular bioeconomy context.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0761-9) contains supplementary material, which is available to authorised users.
“…Steam explosion pretreatment, catalysed with sulphur dioxide (SO 2 ), along with simultaneous saccharification and co-fermentation (SScF) was adopted in the process model for ethanol production, based on the promising conversion performance demonstrated in previous studies [54–57]. To minimise enzyme supply costs [58], an on-site cellulase enzyme production unit was modelled in the biorefinery simulation, based on the literature data sourced from the National Renewable Energy Laboratory [59].…”
Section: Methodsmentioning
confidence: 99%
“…1) includes waste water treatment (WWT) and water cycle for CHP unit. In WWT, during anaerobic digestion biogas is produced and sent to CHP unit, while the treated water is recycled internally [57]. Fig.…”
BackgroundDriven by a range of sustainability challenges, e.g. climate change, resource depletion and expanding populations, a circular bioeconomy is emerging and expected to evolve progressively in the coming decades. South Africa along with other BRICS countries (Brazil, Russia, India and China) represents the emerging bioeconomy and contributes significantly to global sugar market. In our research, South Africa is used as a case study to demonstrate the sustainable design for the future biorefineries annexed to existing sugar industry. Detailed techno-economic evaluation and Life Cycle Assessment (LCA) were applied to model alternative routes for converting sugarcane residues (bagasse and trash) to selected biofuel and/or biochemicals (ethanol, ethanol and lactic acid, ethanol and furfural, butanol, methanol and Fischer–Tropsch synthesis, with co-production of surplus electricity) in an energy self-sufficient biorefinery system.ResultsEconomic assessment indicated that methanol synthesis with an internal rate of return (IRR) of 16.7% and ethanol–lactic acid co-production (20.5%) met the minimum investment criteria of 15%, while the latter had the lowest sensitivity to market price amongst all the scenarios. LCA results demonstrated that sugarcane cultivation was the most significant contributor to environmental impacts in all of the scenarios, other than the furfural production scenario in which a key step, a biphasic process with tetrahydrofuran solvent, had the most significant contribution.ConclusionOverall, the thermochemical routes presented environmental advantages over biochemical pathways on most of the impact categories, except for acidification and eutrophication. Of the investigated scenarios, furfural production delivered the inferior environmental performance, while methanol production performed best due to its low reagent consumption. The combined techno-economic and environmental assessments identified the performance-limiting steps in the 2G biorefinery design for sugarcane industry and highlighted the technology development opportunities under circular bioeconomy context.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0761-9) contains supplementary material, which is available to authorised users.
“…The developed models were attached as supplementary material to facilitate transparency and reproducibility (Supplementary materials 1-4). The boiler was operated at 257 °C and 4.5 MPa, which used 10% excess oxygen from air based on the biomass selected [20]. The excess oxygen was adjusted with the flow to provide complete The boiler was operated at 257 • C and 4.5 MPa, which used 10% excess oxygen from air based on the biomass selected [20].…”
Section: Model Developmentmentioning
confidence: 99%
“…The boiler was operated at 257 °C and 4.5 MPa, which used 10% excess oxygen from air based on the biomass selected [20]. The excess oxygen was adjusted with the flow to provide complete The boiler was operated at 257 • C and 4.5 MPa, which used 10% excess oxygen from air based on the biomass selected [20]. The excess oxygen was adjusted with the flow to provide complete combustion of the material.…”
Abstract:The moisture content of biomass affects its processing for applications such as electricity or steam. In this study, the effects of variation in moisture content of banagrass and energycane was evaluated using techno-economic analysis and life-cycle assessments. A 25% loss of moisture was assumed as a variation that was achieved by field drying the biomass. Techno-economic analysis revealed that high moisture in the biomass was not economically feasible. Comparing banagrass with energycane, the latter was more economically feasible; thanks to the low moisture and ash content in energycane. About 32 GWh/year of electricity was produced by field drying 60,000 dry MT/year energycane. The investment for different scenarios ranged between $17 million and $22 million. Field-dried energycane was the only economically viable option that recovered the investment after 11 years of operation. This scenario was also more environmentally friendly, releasing 16-gCO 2 equivalent/MJ of electricity produced.
“…An increase in fuel production leads to an increase in food prices and has triggered a debate over food versus fuel . Although the commercial‐scale production of second‐generation biofuels is now a reality, its implementation still has challenges . With biochemical conversion technology, investment costs are significantly higher for cellulosic ethanol than for cornstarch‐ or sugarcane‐derived alcohol .…”
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