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Detailed material balance and ethanol yield calculations for the biomass-to-ethanol conversion process

  • Christos Hatzis
  • Cynthia Riley
  • George P. Philippidis
Session 3 Bioprocessing Research

Abstract

Applying material balance calculations to the evaluation and optimization of lignocellulosic biomass conversion processes is fundamentally important. The lack of a general framework for material balance calculations and inconsistent compositional analysis data have made it difficult to compare results from different research groups. Material balance templates have been developed to follow accurately the distribution of carbon in lignocellulosic substrates through the pretreatment and simultaneous saccharification and fermentation (SSF) processes, and provide information on overall carbon recovery, recovery of individual sugars, and solubilization of biomass components. Based on material balance considerations, we developed equations that allow us to compute overall ethanol yields for biochemical conversion of biomass correctly.

Index Entries

Carbon balance dilute-acid pretreatment simultaneous saccharification and fermentation enzymatic conversion overall yield 

Nomenclature

C-mol

amount (mass) of a substance containing 1 mol of the element carbon (g)

[C5]

concentration of pentose sugars in hydrolysate (g / L)

[C6]

concentration of hexose sugars in hydrolysate (g/L)

dL

density of liquor (SSF or hydrolysate) (g/L)

[E]

ethanol concentration (g/L)

fs

fraction of insoluble solids (g insoluble solids / g slurry)

Lf

mass-loss factor of insoluble solids from pretreatment (g pretreated solids/g raw solids)

m

mass of whole slurry (g)

mL

mass of liquid phase (g)

ms

mass of insoluble solids (g)

QC5

mass fraction of pentose sugars in raw substrate (g/g dry mass)

QC6

mass fraction of hexose sugars in raw substrate (g/g dry mass)

YE

ethanol yield (g/100 g hexose sugar)

Subscripts

L

liquid-phase composition or mass

max

maximal potential yield

0

raw substrate or beginning of SSF (t = 0)

p

substrate or solids compositions after pretreatment

s

solids composition or mass.

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Copyright information

© Humana Press Inc. 1996

Authors and Affiliations

  • Christos Hatzis
    • 1
  • Cynthia Riley
    • 2
  • George P. Philippidis
    • 1
  1. 1.Bioprocess Development BranchNational Renewable Energy Laboratory (NREL)Golden
  2. 2.Analysis and Project Management Branch, Alternative Fuels DivisionNational Renewable Energy Laboratory (NREL)Golden

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