Integration options for high energy efficiency and improved economics in a wood-to-ethanol process

Sassner, Per; Zacchi, Guido

doi:10.1186/1754-6834-1-4

Cited by 51 publications

(43 citation statements)

References 22 publications

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“…The physical property database that was developed by the NREL [44] for components in biofuels, such as lignin and cellulose, was used for the biomass components in the simulations. More recent versions the Aspen Plus models by Wingren et al [45,46], Sassner and Zacchi [47], and Joelsson et al [48] were used to perform the simulations.…”

Section: Simulation Toolsmentioning

confidence: 99%

Combined production of biogas and ethanol at high solids loading from wheat straw impregnated with acetic acid: experimental study and techno-economic evaluation

Joelsson

Dienes

Kovács

et al. 2016

Sustain Chem Process

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Background: Production of ethanol and biogas from acetic acid-impregnated steam-pretreated wheat straw was investigated. The solid fraction after pretreatment was used at high solids concentrations to generate ethanol by simultaneous saccharification and fermentation (SSF). The residual streams were evaluated with regard to biogas production. The experimental results were used to perform a techno-economic evaluation of a biorefinery concerning ethanol, raw biogas, pellet, and electricity production at various solid contents and residence times in the fermentation step. The configurations were also altered to include biogas upgrading to vehicle fuel quality or fermentation of xylose to ethanol. Results:At a water-insoluble solids (WIS) content in the SSF of between 10 and 20 %, the ethanol yields exceeded 80 %, the highest being 86 % at 12.5 % WIS, expressed as % of the theoretical maximum, based on the glucan content in SSF. Anaerobic digestion of wheat straw hydrolysate and stillage yielded 4.8 and 1.0-1.2 g methane/100 g dry straw, respectively, in 7-day experiments. Maximum recovery of overall product was achieved when SSF was run at between 10 and 15 % initial WIS content, for which the product yields from 100 g dry wheat straw were 16.1-16.3 g ethanol, 5.8-6.0 g methane, and 25 g lignin-rich solid residue. The net present value (NPV) was negative at discount rate of 11 % but positive at 5 % discount rate for all configurations. The 20 % WIS configuration with a residence time of 96 h in the fermentation stage attained the highest NPV. The minimum ethanol selling price varied between 0.72 and 0.87 EUR/L ethanol when the biogas was unchanged and it decreased to between 0.46 and 0.60 EUR/L ethanol when the biogas was upgraded to vehicle fuel quality or when xylose was converted to ethanol. Conclusions:According to the techno-economic assessment, a process that is based on the fermentation of only hexoses to ethanol, and production of raw biogas from xylose is not profitable under the economic assumptions including 11 % discount rate in the evaluation. However, the profitability of a plant can be improved by biogas upgrading to vehicle fuel quality or fermentation of xylose to ethanol.

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Section: Simulation Toolsmentioning

confidence: 99%

Combined production of biogas and ethanol at high solids loading from wheat straw impregnated with acetic acid: experimental study and techno-economic evaluation

Joelsson

Dienes

Kovács

et al. 2016

Sustain Chem Process

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“…The production costs of bioethanol from energy crops vary widely due to the complex characteristics of the resource, their site specificity, national policies, labor costs and efficiency of the conversion technologies, but are expected to decline over time 110 and it is noted to have clear socioeconomic benefits 50 . The coproduct revenue and utilization of the excess solid residue for heat and power production had a considerable effect on the process economics, and improved ethanol yield and reduced energy demand resulted in significant production cost reductions (0.41-0.50 €/L) 100,101 . Sassner et al 101 also concluded that the utilization of pentose fractions for ethanol production helped achieve good process economy, especially in the case of Salix or corn stover.…”

Section: Cost Analysismentioning

confidence: 99%

A Review of Life Cycle Assessment (LCA) of Bioethanol from Lignocellulosic Biomass

Roy

Tokuyasu

Orikasa

et al. 2012

JARQ

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Liquid biofuels are widely recognized alternatives to fossil fuel not only to combat the global warming potential, but also to reduce the reliance on fossil fuels to facilitate economic development. The production and use of lignocellulosic liquid biofuel have been emphasized because it is highly reproducible and does not compete with food. This study summarizes the LCA studies on lignocellulosic ethanol produced from various biomass resources focusing on energy balance, greenhouse gas (GHG) emission and other impact categories, and the production cost to discuss their potential environmental and socioeconomic impacts. Numerous efforts have been made to evaluate the life cycle of lignocellulosic ethanol with LCA methodologies and deals with feedstock, energy paths, conversion technologies, allocation methods, utilization of by-products etc. to determine the environmental impacts as well as the production cost. The environmental benefits are reported in most of the studies except for few examples. A wide variation was observed in the reported production cost of ethanol, which is dependent on the feedstock, conversion technologies, allocation methods and plant sizes. Onsite enzymes production/purchase appeared to be the main hotspot, demands a vigorous study to improve their productivity and reduce costs. Another promising alternative for compensating production costs seem to be the generation of valuable coproducts and integration of ethanol production processes (ethanol and energy). Reviewed literature indicates that despite the environmental benefits of ethanol produced from lignocellulosic biomass, its economic viability remains doubtful at present, even if highly optimistic assumptions are made for the cost calculation, especially in the case of enzyme. Hence, the biotechnological revolution is must for the sustainability of bioethanol, especially in the field of enzymes and microorganisms. Moreover, the adaptation of innovative technologies and renewable energy policy may help limit costs, but careful consideration of land use changes and soil quality is required to avoid any loss of productivity.

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“…Within the two base cases 14 scenarios were investigated, which differed in process configuration and values of parameters. The configurations are shown Process considerations of a biorefinery producing value-added products from corn fibre 13 2012 56 1 mechanical efficiency of the low-pressure turbine are presumed to 85% and 97%, respectively [12]. The xylitol fermentation and recovery steps are implemented only in the base case B, in which the hydrolysed hemicellulosic sugars are separated from the solid fraction, before the ethanol fermentation.…”

Section: Comparison Of the Scenariosmentioning

confidence: 99%

“…The pressure of steam after the low-pressure turbine is set to 1 bar. The isentropic and the mechanical efficiency of the low-pressure turbine are presumed to 85% and 97%, respectively [12].…”

Section: Combined Heat and Power Productionmentioning

confidence: 99%

“…Increased productivity and efficiency can be achieved through operations that decrease overall energy demand of the biorefin-ery process [11]. Many opportunities were discussed with the potential to achieve this goal: i; increasing the dry matter (DM) content during the ethanol fermentation to decrease the energy demand of the distillation step [5] ii; heat integration of the process steps [12] iii; anaerobic digestion of the stillage [13].…”

Section: Introductionmentioning

confidence: 99%

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Process considerations of a biorefinery producing value-added products from corn fibre

Fehér¹,

Barta²,

Réczey³

2012

Per. Pol. Chem. Eng.

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Corn fibre, a co-product of corn wet milling, can be a suitable raw material of a biorefinery producing biofuels and valueadded chemicals. The simulated process is able to produce bioethanol, biomethane and xylitol synergistically, while it also covers its own heat demand. The proposed plant consists of the following process steps: fractionation, enzymatic hydrolysis and ethanol fermentation, distillation and dehydration, anaerobic digestion, biogas upgrading, aerobic waste water treatment, combined heat and power production, xylitol fermentation and recovery. Various scenarios of the biorefinery were investigated and the process configurations were compared in terms of energy efficiency, or mass flows of the products. Incineration of the sludge and production of district heat are found to be effective methods to increase the energy efficiency, on which aerobic sludge yield has a great effect. The solid-liquid separations, which are carried out in filterpress, have a curial role in terms of energy efficiency. Combustion of the solid part of cellulose hydrolysis residue is favourable compared with the anaerobic digestion, except if the dry matter content of the filterpressed solid was set to 30% instead of 40%. The amounts of the produced xylitol and biomethane are variable, which ensures the ability of market adaptation for the biorefinery.

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Integration options for high energy efficiency and improved economics in a wood-to-ethanol process

Cited by 51 publications

References 22 publications

Combined production of biogas and ethanol at high solids loading from wheat straw impregnated with acetic acid: experimental study and techno-economic evaluation

Combined production of biogas and ethanol at high solids loading from wheat straw impregnated with acetic acid: experimental study and techno-economic evaluation

A Review of Life Cycle Assessment (LCA) of Bioethanol from Lignocellulosic Biomass

Process considerations of a biorefinery producing value-added products from corn fibre

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