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Process considerations and economic evaluation of two-step steam pretreatment for production of fuel ethanol from softwood

Wingren, Anders LU ; Söderström, Johanna LU ; Galbe, Mats LU and Zacchi, Guido LU (2004) In Biotechnology Progress 20(5). p.1421-1429
Abstract
To increase the overall ethanol yield from softwood, the steam pretreatment stage can be carried out in two steps. The two-step pretreatment process was evaluated from a techno-economic standpoint and compared with the one-step pretreatment process. The production plants considered were designed to utilize spruce as raw material and have a capacity of 200 000 tons/year. The two-step process resulted in a higher ethanol yield and a lower requirement for enzymes. However, the two-step process is more capital-intensive and has a higher energy requirement. The estimated ethanol production cost was the same, 4.13 SEK/L (55.1 cent/L) for both alternatives. For the two-step process different energy-saving options were considered, such as a higher... (More)
To increase the overall ethanol yield from softwood, the steam pretreatment stage can be carried out in two steps. The two-step pretreatment process was evaluated from a techno-economic standpoint and compared with the one-step pretreatment process. The production plants considered were designed to utilize spruce as raw material and have a capacity of 200 000 tons/year. The two-step process resulted in a higher ethanol yield and a lower requirement for enzymes. However, the two-step process is more capital-intensive and has a higher energy requirement. The estimated ethanol production cost was the same, 4.13 SEK/L (55.1 cent/L) for both alternatives. For the two-step process different energy-saving options were considered, such as a higher concentration of water-insoluble solids in the filter cake before the second step, and the possibility of excluding the pressure reduction between the steps. The most optimistic configuration, with 50% water-insoluble solids in the filter cake in the feed to the second pretreatment step, no pressure reduction between the pretreatment steps, and 77% overall ethanol yield (0.25 kg EtOH/kg dry wood), resulted in a production cost of 3.90 SEK/L (52.0 cent/L). This shows the potential for the two-step pretreatment process, which, however, remains to be verified in pilot trials. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biotechnology Progress
volume
20
issue
5
pages
1421 - 1429
publisher
The American Chemical Society
external identifiers
  • wos:000224377700016
  • scopus:5544244645
ISSN
1520-6033
DOI
10.1021/bp049931v
language
English
LU publication?
yes
id
a3f0aec0-bde1-4903-a304-6f0c82f463f6 (old id 138775)
date added to LUP
2007-06-25 16:39:43
date last changed
2017-12-10 04:32:44
@article{a3f0aec0-bde1-4903-a304-6f0c82f463f6,
  abstract     = {To increase the overall ethanol yield from softwood, the steam pretreatment stage can be carried out in two steps. The two-step pretreatment process was evaluated from a techno-economic standpoint and compared with the one-step pretreatment process. The production plants considered were designed to utilize spruce as raw material and have a capacity of 200 000 tons/year. The two-step process resulted in a higher ethanol yield and a lower requirement for enzymes. However, the two-step process is more capital-intensive and has a higher energy requirement. The estimated ethanol production cost was the same, 4.13 SEK/L (55.1 cent/L) for both alternatives. For the two-step process different energy-saving options were considered, such as a higher concentration of water-insoluble solids in the filter cake before the second step, and the possibility of excluding the pressure reduction between the steps. The most optimistic configuration, with 50% water-insoluble solids in the filter cake in the feed to the second pretreatment step, no pressure reduction between the pretreatment steps, and 77% overall ethanol yield (0.25 kg EtOH/kg dry wood), resulted in a production cost of 3.90 SEK/L (52.0 cent/L). This shows the potential for the two-step pretreatment process, which, however, remains to be verified in pilot trials.},
  author       = {Wingren, Anders and Söderström, Johanna and Galbe, Mats and Zacchi, Guido},
  issn         = {1520-6033},
  language     = {eng},
  number       = {5},
  pages        = {1421--1429},
  publisher    = {The American Chemical Society},
  series       = {Biotechnology Progress},
  title        = {Process considerations and economic evaluation of two-step steam pretreatment for production of fuel ethanol from softwood},
  url          = {http://dx.doi.org/10.1021/bp049931v},
  volume       = {20},
  year         = {2004},
}