Techno-economic comparison of ethanol and electricity coproduction schemes from sugarcane residues at existing sugar mills in Southern Africa

Petersen, Abdul M.; Aneke, Mathew; Görgens, Johann F.

doi:10.1186/1754-6834-7-105

Cited by 36 publications

(35 citation statements)

References 59 publications

(122 reference statements)

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“…Electricity from bagasse plays an important role in modern sugarcane processing plants . In the sugarcane plant, bagasse is burned to produce steam and electricity for the plant, with the surplus electricity sold to the grid to generate co‐product credits. The steam and electricity requirements for the processes of soybean biodiesel, sugarcane, and lipid‐cane with 10 and 20% lipid contents are shown in Table .…”

Section: Resultsmentioning

confidence: 99%

Techno‐economic analysis of biodiesel and ethanol co‐production from lipid‐producing sugarcane

Huang

Long

Singh

2016

Biofuels Bioprod Bioref

119

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Biodiesel production from vegetable oils has progressively increased over the past two decades. However, due to the low amounts of oil produced per hectare from temperate oilseed crops (e.g. soybean), the opportunities for further increasing biodiesel production are limited. Genetically modifi ed lipid-producing sugarcane (lipid-cane) possesses great potential for producing biodiesel as an alternative feedstock because of sugarcane's much higher productivity compared with soybean. In this study, techno-economic models were developed for biodiesel and ethanol coproduction from lipid-cane, assuming 2, 5, 10, or 20% lipid concentration in the harvested stem (dry mass basis). The models were compared with a conventional soybean biodiesel process model to assess lipid-cane's competiveness. In the lipid-cane process model, the extracted lipids were used to produce biodiesel by transesterifi cation, and the remaining sugar was used to produce ethanol by fermentation. The results showed that the biodiesel production cost from lipid-cane decreased from $0.89/L to $0.59 /L as the lipid content increased from 2 to 20%; this cost was lower than that obtained for soybeans ($1.08/L). The ethanol production costs from lipid-cane were between $0.40/L and $0.46/L. The internal rate of return (IRR) for the soybean biodiesel process was 15.0%, and the IRR for the lipid-cane process went from 13.7 to 24.0% as the lipid content increased from 2 to 20%. Because of its high productivity, lipid-cane with 20% lipid content can produce 6700 L of biodiesel from each hectare of land, whereas soybean can only produce approximately 500 L of biodiesel from each hectare of land. This would indicate that continued efforts to achieve lipid-producing sugarcane could make large-scale replacement of fossil-fuelderived diesel without unrealistic demands on land area.

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Section: Resultsmentioning

confidence: 99%

Techno‐economic analysis of biodiesel and ethanol co‐production from lipid‐producing sugarcane

Huang

Long

Singh

2016

Biofuels Bioprod Bioref

119

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“…Given the uncertainty in the selling price of the export electricity, an upper and lower premium was calculated and applied on the base electricity prices projected from the probability distribution. These premiums were calculated on the minimum and maximum prices for renewable electricity of the South African Renewable Energy bids, which had 2012 based prices of 0.113 and 0.175 US$ per kW/hr respectively [101]. Since biomass based energy is continuous and supplies energy for peak hours, a bonus price of two times the renewable energy price is allowed for four hours per day [101], which thus raises the average renewable prices to 0.139 and 0.216 US$ per kW/hr.…”

Section: Nominal Economic Variablesmentioning

confidence: 99%

“…These premiums were calculated on the minimum and maximum prices for renewable electricity of the South African Renewable Energy bids, which had 2012 based prices of 0.113 and 0.175 US$ per kW/hr respectively [101]. Since biomass based energy is continuous and supplies energy for peak hours, a bonus price of two times the renewable energy price is allowed for four hours per day [101], which thus raises the average renewable prices to 0.139 and 0.216 US$ per kW/hr. Relative to the base electricity price (2012 price) in Table 8, the upper and lower premiums amount to 31% and 103% respectively.…”

Section: Nominal Economic Variablesmentioning

confidence: 99%

Bioelectricity Versus Bioethanol From Sugarcane Bagasse: Is It Worth Being Flexible?

2015

Sugarcane as Biofuel Feedstock

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Background: The economics of producing only electricity from residues, which comprise of surplus bagasse and 50% post-harvest residues, at an existing sugar mill in South Africa was compared to the coproduction of ethanol from the hemicelluloses and electricity from the remaining solid fractions. Six different energy schemes were evaluated. They include: (1) exclusive electricity generation by combustion with high pressure steam cycles (CHPSC-EE), (2) biomass integrated gasification with combined cycles (BIGCC-EE), (3) coproduction of ethanol (using conventional distillation (CD)) and electricity (using BIGCC), (4) coproduction of ethanol (using CD) and electricity (using CHPSC), (5) coproduction of ethanol (using vacuum distillation (VD)) and electricity (using BIGCC), and (6) coproduction of ethanol (using VD) and electricity (using CHPSC). The pricing strategies in the economic analysis considered an upper and lower premium for electricity, on the standard price of the South African Energy Provider Eskom' of 31 and 103% respectively and ethanol prices were projected from two sets of historical prices.

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“…Sugarcane bagasse is one of the most abundant byproducts of agroindustry in south China as well as the world [1]. Meanwhile, Jerusalem artichoke is a typical example of the energy crops which can grow in marginal lands, including saline soils and sandy soils, owing to its unique agronomic traits such as tolerance to salt and drought stresses, and thus does not compete for arable lands with grain crops [2].…”

Section: Introductionmentioning

confidence: 99%

Synergy of crude enzyme cocktail from cold-adapted Cladosporium cladosporioides Ch2-2 with commercial xylanase achieving high sugars yield at low cost

Yang

Fan

et al. 2014

Biotechnol Biofuels

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BackgroundThe efficiency and cost of current lignocellulosic enzymes still limit the large-scale production of cellulosic ethanol in industry. Residual lignin after pretreatment severely depresses the activity of polysaccharide hydrolases and the h ydrolysis of holocellulose. If we include in hydrolase mixture construction the ligninase involved in lignin degradation, which mainly includes laccase, manganese peroxidases (MnP) and lignin peroxidase (LiP), it is feasible that this could greatly improve the fermentable sugars yield.ResultsThe psychrophilic lignocellulosic enzymes system of Cladosporium cladosporioides Ch2-2 including ligninase and polysaccharide hydrolases was suitable for selective delignification and efficient saccharification of biomass with wide thermal adaptability. The purified laccase was optimally active at 15°C and pH 3.5, exhibiting high thermostability over a broad range of temperatures (between 4 and 40°C). In addition, manganese-independent peroxidase (MIP), a special type of ligninase with the capacity to oxidize dimethyl phthalate (DMP) in the absence of H2O2 and Mn2+, was optimally active at 20°C and pH 2.5, exhibiting high thermostability over a broad range of temperatures (4 and 28°C), while depressed completely by Fe2+ and essentially unaffected by EDTA. Synergy between Ch2-2 crude enzymes and commercial xylanase obviously enhanced biomass hydrolysis, which could take the place of expensive commercial cellulase mixture. The maximum value of synergistic degree reached 4.7 at 28°C, resulting in 10.1 mg/mL reducing sugars.ConclusionsThe psychrophilic enzymes system of C. cladosporioides Ch2-2 with a different synergistic mechanism has huge potential for the enhancement of biomass hydrolysis at mesophilic and low temperatures. The application scope of the lignocellulosic enzyme cocktail could be greatly enlarged by optimizing the operation conditions specific to the characteristics of ligninase.

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Techno-economic comparison of ethanol and electricity coproduction schemes from sugarcane residues at existing sugar mills in Southern Africa

Cited by 36 publications

References 59 publications

Techno‐economic analysis of biodiesel and ethanol co‐production from lipid‐producing sugarcane

Techno‐economic analysis of biodiesel and ethanol co‐production from lipid‐producing sugarcane

Bioelectricity Versus Bioethanol From Sugarcane Bagasse: Is It Worth Being Flexible?

Synergy of crude enzyme cocktail from cold-adapted Cladosporium cladosporioides Ch2-2 with commercial xylanase achieving high sugars yield at low cost

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