Projected mature technology scenarios for conversion of cellulosic biomass to ethanol with coproduction thermochemical fuels, power, and/or animal feed protein

Laser, Mark; Jin, Haiming; Jayawardhana, Kemantha; Dale, Bruce E.; Lynd, Lee R.

doi:10.1002/bbb.131

Cited by 64 publications

(50 citation statements)

References 12 publications

(23 reference statements)

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“…The enzyme production costs are tightly interlinked with the protein yield of cellulase in the fermentation broth as well as the enzyme activity. Therefore, continuous efforts towards the cost reduction of enzymes and increasing the overall protein production have been routed towards exploring hyperactive microbial strains, efficient fermentation techniques and cost-effective recovery systems (Laser et al 2009). Use of different mutagenic agents for microbial strain improvement and fermentation processes was demonstrated by Parekh et al (2000).…”

Section: Introductionmentioning

confidence: 99%

Use of combined UV and chemical mutagenesis treatment of Aspergillus terreus D34 for hyper-production of cellulose-degrading enzymes and enzymatic hydrolysis of mild-alkali pretreated rice straw

Kumar

Parikh

Singh

et al. 2015

Bioresour. Bioprocess.

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Background: Microbial production of cellulose-degrading enzymes could be significantly improved using traditional mutagenesis treatment. Development of high-titre cellulase producing mutants drastically reduces the costs involved in cellulase production and downstream processing in commercial-scale enzyme production. Here, we have evaluated the efficacy of different Aspergillus terreus D34 mutants for hyper-production of improved cellulase enzymes utilizing locally available lignocellulosic biomass residues as growth substrates in solid state fermentation conditions. Further, enzymatic hydrolysis of mild-alkali pre-treated rice straw was performed using the improved cellulases.Results: A 4.9-fold higher β-glucosidase activity was obtained from ethyl methyl sulphonate (EMS) treated mutant strain (EMS2) when grown on mixed rice straw/sugarcane bagasse (RSBG) biomass growth substrate. Similarly with the EMS2 mutant and BG-grown culture extract a 1.1-fold higher xylanase activity was observed. Irrespective of the growth substrates and the mutant strains, the maximum cellulase (FPase, carboxymethyl cellulase, avicelase, β-glucosidase) and xylanase activities (U mL −1 ) were 2.34, 39.8, 2.46, 19.9 and 655, respectively. Further, external supplementation of 20% bovine serum albumin (BSA), 3% tween 80 and 20% polyethylene glycol (PEG) 6000 to the crude enzyme extract increased the FPase activity nearly 4.0-, 2.8-and 2.2-fold. Addition of 0.05% sodium benzoate marginally increased the stability of cellulase enzyme and retained more than 60% of the initial activity after 96 h incubation at 37°C. While at 4°C, no loss in enzyme activity was observed even after prolonged incubation period (up to 90 days). Further, maximum reducing sugars of 0.842 g g −1 at a rate of 0.25 mM g −1 h −1 at 10% biomass loading of mild-alkali pretreated rice straw was produced using the BG-grown culture extract of EMS2 mutant strain. Conclusion:The extracellular protein production and corresponding cellulase activities of A. terreus D34 were significantly enhanced after combined UV and chemical mutagenesis treatments. In the present study, besides accelerating the rate of cellulase production, we have also demonstrated production of high reducing sugars by enzymatic saccharification of pretreated lignocellulosic biomass using hyper-produced cellulase enzymes. Due to high enzyme activity of the cellulase enzymes produced from the mutant strains, the volume of enzyme loadings in enzymatic hydrolysis could be reduced up to 7-fold. These studies clearly show the potential of the developed hyper-cellulase producing mutants in decreasing the overall process economics of cellulosic ethanol technology.

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Section: Introductionmentioning

confidence: 99%

Use of combined UV and chemical mutagenesis treatment of Aspergillus terreus D34 for hyper-production of cellulose-degrading enzymes and enzymatic hydrolysis of mild-alkali pretreated rice straw

Kumar

Parikh

Singh

et al. 2015

Bioresour. Bioprocess.

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“…Further, there are advantages in the handling, combustion, and transportation of gaseous fuel over solid fuels which are not reflected in the costs. In several studies, moisture content was identified as an important factor in thermochemical conversion and combined heat and power processes due to an increased heat of vaporization (Caputo et al 2005;Phillips et al 2007;Laser et al 2009;Dutta et al 2011;Gonzalez et al 2012;Verma et al 2012). …”

Section: Delivered Cost Per Million Btumentioning

confidence: 99%

Economics, Environmental Impacts, and Supply Chain Analysis of Cellulosic Biomass for Biofuels in the Southern US: Pine, Eucalyptus, Unmanaged Hardwoods, Forest Residues, Switchgrass, and Sweet Sorghum

Daystar¹,

Gonzalez²,

Reeb³

et al. 2013

BioResources

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The production of six regionally important cellulosic biomass feedstocks, including pine, eucalyptus, unmanaged hardwoods, forest residues, switchgrass, and sweet sorghum, was analyzed using consistent life cycle methodologies and system boundaries to identify feedstocks with the lowest cost and environmental impacts. Supply chain analysis was performed for each feedstock, calculating costs and supply requirements for the production of 453,592 dry tonnes of biomass per year. Cradle-togate environmental impacts from these modeled supply systems were quantified for nine mid-point indicators using SimaPro 7.2 LCA software. Conversion of grassland to managed forest for bioenergy resulted in large reductions in GHG emissions due to carbon uptake associated with direct land use change. By contrast, converting forests to cropland resulted in large increases in GHG emissions. Production of forest-based feedstocks for biofuels resulted in lower delivered cost, lower greenhouse gas (GHG) emissions, and lower overall environmental impacts than the agricultural feedstocks studied. Forest residues had the lowest environmental impact and delivered cost per dry tonne. Using forest-based biomass feedstocks instead of agricultural feedstocks would result in lower cradle-to-gate environmental impacts and delivered biomass costs for biofuel production in the southern U.S.

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“…Both the biological (hydrolysis-fermentation) and thermochemical (gasification -synthesis) processes require the use of advanced, high-efficiency equipment for electricity production, to satisfy process requirements and provide surplus electricity for sale [89,90]. However, advanced equipment such as BIG/ CC systems [84,91,92] have high capital costs per unit electricity [19,93]. Economies of scale achieved through integration of electricity production in second-generation biofuel processes with electricity production in adjacent industrial facilities can reduce capital investment per unit of electricity substantially [24,90,92,94 -96].…”

Section: Energy Integration Between Lignocellulosic Conversion Procesmentioning

confidence: 99%

Next-generation cellulosic ethanol technologies and their contribution to a sustainable Africa

et al. 2011

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The world is currently heavily dependent on oil, especially in the transport sector. However, rising oil prices, concern about environmental impact and supply instability are among the factors that have led to greater interest in renewable fuel and green chemistry alternatives. Lignocellulose is the only foreseeable renewable feedstock for sustainable production of transport fuels. The main technological impediment to more widespread utilization of lignocellulose for production of fuels and chemicals in the past has been the lack of low-cost technologies to overcome the recalcitrance of its structure. Both biological and thermochemical second-generation conversion technologies are currently coming online for the commercial production of cellulosic ethanol concomitantly with heat and electricity production. The latest advances in biological conversion of lignocellulosics to ethanol with a focus on consolidated bioprocessing are highlighted. Furthermore, integration of cellulosic ethanol production into existing bio-based industries also using thermochemical processes to optimize energy balances is discussed. Biofuels have played a pivotal yet suboptimal role in supplementing Africa's energy requirements in the past. Capitalizing on sub-Saharan Africa's total biomass potential and using second-generation technologies merit a fresh look at the potential role of bioethanol production towards developing a sustainable Africa while addressing food security, human needs and local wealth creation.

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Projected mature technology scenarios for conversion of cellulosic biomass to ethanol with coproduction thermochemical fuels, power, and/or animal feed protein

Cited by 64 publications

References 12 publications

Use of combined UV and chemical mutagenesis treatment of Aspergillus terreus D34 for hyper-production of cellulose-degrading enzymes and enzymatic hydrolysis of mild-alkali pretreated rice straw

Use of combined UV and chemical mutagenesis treatment of Aspergillus terreus D34 for hyper-production of cellulose-degrading enzymes and enzymatic hydrolysis of mild-alkali pretreated rice straw

Economics, Environmental Impacts, and Supply Chain Analysis of Cellulosic Biomass for Biofuels in the Southern US: Pine, Eucalyptus, Unmanaged Hardwoods, Forest Residues, Switchgrass, and Sweet Sorghum

Next-generation cellulosic ethanol technologies and their contribution to a sustainable Africa

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