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Techno-economic evaluation of stillage treatment with anaerobic digestion in a softwood-to-ethanol process.

Barta, Zsolt LU ; Reczey, Kati and Zacchi, Guido LU (2010) In Biotechnology for Biofuels 3.
Abstract
ABSTRACT: BACKGROUND: Replacing the energy-intensive evaporation of stillage by anaerobic digestion is one way of decreasing the energy demand of the lignocellulosic biomass to the ethanol process. The biogas can be upgraded and sold as transportation fuel, injected directly into the gas grid or be incinerated on-site for combined heat and power generation. A techno-economic evaluation of the spruce-to-ethanol process, based on SO2-catalysed steam pretreatment followed by simultaneous saccharification and fermentation, has been performed using the commercial flow-sheeting program Aspen Plus™. Various process configurations of anaerobic digestion of the stillage, with different combinations of co-products, have been evaluated in terms of... (More)
ABSTRACT: BACKGROUND: Replacing the energy-intensive evaporation of stillage by anaerobic digestion is one way of decreasing the energy demand of the lignocellulosic biomass to the ethanol process. The biogas can be upgraded and sold as transportation fuel, injected directly into the gas grid or be incinerated on-site for combined heat and power generation. A techno-economic evaluation of the spruce-to-ethanol process, based on SO2-catalysed steam pretreatment followed by simultaneous saccharification and fermentation, has been performed using the commercial flow-sheeting program Aspen Plus™. Various process configurations of anaerobic digestion of the stillage, with different combinations of co-products, have been evaluated in terms of energy efficiency and ethanol production cost versus the reference case of evaporation. RESULTS: Anaerobic digestion of the stillage showed a significantly higher overall energy efficiency (87-92%), based on the lower heating values, than the reference case (81%). Although the amount of ethanol produced was the same in all scenarios, the production cost varied between 4.00 and 5.27 Swedish kronor per litre (0.38-0.50 euro/L), including the reference case. CONCLUSIONS: Higher energy efficiency options did not necessarily result in lower ethanol production costs. Anaerobic digestion of the stillage with biogas upgrading was demonstrated to be a favourable option for both energy efficiency and ethanol production cost. The difference in the production cost of ethanol between using the whole stillage or only the liquid fraction in anaerobic digestion was negligible for the combination of co-products including upgraded biogas, electricity and district heat. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biotechnology for Biofuels
volume
3
publisher
BioMed Central
external identifiers
  • wos:000282629300001
  • pmid:20843330
  • scopus:77956540771
ISSN
1754-6834
DOI
10.1186/1754-6834-3-21
language
English
LU publication?
yes
id
2be873c7-33e7-4e63-bbe2-5eb188625ed0 (old id 1688253)
date added to LUP
2010-10-18 12:09:31
date last changed
2018-07-01 03:51:26
@article{2be873c7-33e7-4e63-bbe2-5eb188625ed0,
  abstract     = {ABSTRACT: BACKGROUND: Replacing the energy-intensive evaporation of stillage by anaerobic digestion is one way of decreasing the energy demand of the lignocellulosic biomass to the ethanol process. The biogas can be upgraded and sold as transportation fuel, injected directly into the gas grid or be incinerated on-site for combined heat and power generation. A techno-economic evaluation of the spruce-to-ethanol process, based on SO2-catalysed steam pretreatment followed by simultaneous saccharification and fermentation, has been performed using the commercial flow-sheeting program Aspen Plus™. Various process configurations of anaerobic digestion of the stillage, with different combinations of co-products, have been evaluated in terms of energy efficiency and ethanol production cost versus the reference case of evaporation. RESULTS: Anaerobic digestion of the stillage showed a significantly higher overall energy efficiency (87-92%), based on the lower heating values, than the reference case (81%). Although the amount of ethanol produced was the same in all scenarios, the production cost varied between 4.00 and 5.27 Swedish kronor per litre (0.38-0.50 euro/L), including the reference case. CONCLUSIONS: Higher energy efficiency options did not necessarily result in lower ethanol production costs. Anaerobic digestion of the stillage with biogas upgrading was demonstrated to be a favourable option for both energy efficiency and ethanol production cost. The difference in the production cost of ethanol between using the whole stillage or only the liquid fraction in anaerobic digestion was negligible for the combination of co-products including upgraded biogas, electricity and district heat.},
  articleno    = {21},
  author       = {Barta, Zsolt and Reczey, Kati and Zacchi, Guido},
  issn         = {1754-6834},
  language     = {eng},
  publisher    = {BioMed Central},
  series       = {Biotechnology for Biofuels},
  title        = {Techno-economic evaluation of stillage treatment with anaerobic digestion in a softwood-to-ethanol process.},
  url          = {http://dx.doi.org/10.1186/1754-6834-3-21},
  volume       = {3},
  year         = {2010},
}