Strengths, Challenges, and Opportunities for Hydrothermal Pretreatment in Lignocellulosic Biorefineries

Ling Tao, Bin Yang, Charles Wyman

Research output: Contribution to journalArticlepeer-review

107 Scopus Citations

Abstract

Pretreatment prior to or during biological conversion is required to achieve high sugar yields essential to economic production of fuels and chemicals from low cost, abundant lignocellulosic biomass. Aqueous thermochemical pretreatments achieve this performance objective from pretreatment coupled with subsequent enzymatic hydrolysis, but chemical pretreatment can also suffer from additional costs for exotic materials of construction, the need to recover or neutralize the chemicals, introduction of compounds that inhibit downstream operations, and waste disposal, as well as for the chemicals themselves. The simplicity of hydrothermal pretreatment with just hot water offers the potential to greatly improve the cost of the entire conversion process if sugar degradation during pretreatment, production of un-fermentable oligomers, and the amount of expensive enzymes needed to obtain satisfactory yields from hydrothermally pretreated solids can be reduced. Biorefinery economics would also benefit if value could be generated from lignin and other components that are currently fated to be burned for power. However, achieving these goals will no doubt require development of advanced hydrothermal pretreatment configurations. For example, passing water through a stationary bed of lignocellulosic biomass in a flowthrough configuration achieves very high yields of hemicellulose sugars, removes more than 75% of the lignin for potential valorization, and improves sugar release from the pretreated solids with lower enzyme loadings. Unfortunately, the large quantities of water needed to achieve this performance result in very dilute sugars, high energy costs for pretreatment and product recover, and large amounts of oligomers. Thus, improving our understanding of hydrothermal pretreatment fundamentals is needed to gain insights into R&D opportunities to improve performance, and help identify novel configurations that lower capital and operating costs and achieve higher yields.

Original languageAmerican English
Pages (from-to)125-138
Number of pages14
JournalBiofuels, Bioproducts and Biorefining
Volume12
Issue number1
DOIs
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2017 Society of Chemical Industry and John Wiley & Sons, Ltd

NREL Publication Number

  • NREL/JA-5100-70374

Keywords

  • biomass
  • hydrothermal pretreatment
  • lignin
  • sugars
  • water

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