Modeling Biomass
Conversion to
Transportation Fuels
Jacob Miller
Advisor: Dr. Eric Larson
Outline
 What is biomass? Why is it useful?
 What is bioconversion?
 What is biomass made of?
 Manufacturing process
 Model creation: Mass, energy, and carbon balances
 Economic modeling, carbon and energy credits
 Final cost estimates
What is biomass?
Yes
No
Switchgrass
Corn
Soybeans
Corn Stover
Inedible plant matter
Bioconversion
2
Rubin, 2008
Components of Biomass
 What we care about:
 Cellulose, lignin, hemicellulose
Enzymatic hydrolysis,
bioconversion
to fuels
Burned for electricity
Pretreatment,
bioconversion
to fuels
Alonso et al. 2012
3 Core Processes
 Pretreatment: Separate hemicellulose and lignin from
cellulose, depolymerize hemicellulose (in some cases)
 Common methods: dilute acid, steam, ammonia
 Hydrolysis: break cellulose up into individual glucose
monomers
 Method: enzymes (biological catalysts)
 Bioconversion: converts sugars to fuel molecules
 Common example: fermentation of glucose
to ethanol
Model Basis: NREL Model
Process units altered slightly in various scenarios
Davis et al. 2013
Model Creation: Mass, Energy,
and Carbon Balances
Mass flows, kg/hr
=Process CO2 outlets
Final Cost Estimates Sample
Plant Configurations
MFSP: Minimum fuel selling price
Takeaway: cellulosic biofuels won’t be economical without high
CO taxes
Acknowledgements
 Princeton Environmental Institute
 Dr. Eric Larson, Dr. Thomas Kreutz, Dr. Robert
Williams, Dr. Hans Meerman, Maurizio Spinelli
Questions?
Economic Modeling, Carbon
and Energy Credits
 Discounted Cash Flow Analysis
 External power source/replacement: Natural gas
combined cycle plant
 CO2 tax: $0-$100/ton
Components of Biomass
% Dry Mass
Cellulose
% Dry Mass
Hemicellulose
% Dry
Mass
Lignin
Sugarcane
bagasse
35.2
24.5
22.2
18.1
Switchgrass
35.2
30.5
7.7
26.6
Corn stover
34.4
22.8
18
24.8
Plant
% Dry Mass
Other
Rezende et al. 2011
Godin et al. 2013
Kumar et al. 2009
Carbon Capture Integration
 Rectisol
 Less expensive ($1s million capital costs)
 Can only capture CO2 from pressurized sources
 Amine Solvent
 More expensive ($100s million capital costs)
 Can capture CO2 from any emissions source (ex:
biomass generator)