Bioenergy from
Agricultural Wastes
Ann D. Christy, Ph.D., P.E.
Associate Professor
Dept of Food, Agricultural, and
Biological Engineering
USAIN April 2008
World Energy Prospects
Population
(billion)
World's Population
12
10
8
6
4
2
0
10
6.7
Increase in
Population
2008
2050
Year
Source:
•CIA's The World Factbook
• World POPClock Projection, U.S. Census Bureau
• Energy Sources, 26:1119-1129,2004
60%
Energy demand
63160%
Other concerns
Pollution
Climate change
Resource depletion
Renewable energy sources
Summary of energy resources consumption in United States, 2004
•By 2030, bio-energy, 15-20% energy consumption
Source:
USDA-DOE, 2005, http://www.eere.energy.gov/biomass/publications.html.
Overview
Bioenergy history
Ag wastes and other biomass
Biomass to Bioenergy
Conversion processes
Pros & Cons
Applications
Biofuels
Bioheat
Bioelectricity
Some U.S.
bioenergy history
Bioenergy is not new!
1850s: Ethanol used for lighting
(http://www.eia.doe.gov/
kids/energyfacts/sources/renewable/ethanol.html#motorfuel)
1860s-1906: Ethanol tax enacted (making it
no longer competitive with kerosene for lights)
1896: 1st ethanol-fueled automobile, the
Ford Quadricycle
(http://www.nesea.org/greencarclub/factsheets_ethanol.pdf)
More bioenergy
history
(photo from http://www.modelt.org/gallery/picz.asp?iPic=129)
1908: 1st flex-fuel car, the Ford Model T
1919-1933: Prohibition banned ethanol unless
mixed with petroleum
WWI and WWII: Ethanol used due to high oil costs
Early 1960s: Acetone-Butanol-Ethanol industrial
fermentation discontinued in US
Today, about 110 new U.S. ethanol refineries in
operation and 75 more planned
Ag wastes and
other biomass
Waste Biomass
Crop and forestry residues, animal
manure, food processing waste, yard
waste, municipal and C&D solid wastes,
sewage, industrial waste
New Biomass: (Terrestrial & Aquatic)
Solar energy and CO2 converted via
photosynthesis to organic compounds
Conventionally harvested for food, feed,
fiber, & construction materials
Agricultural and Forestry Wastes
Crop residues
Animal manures
Food / feed processing residues
Logging residues (harvesting
and clearing)
Wood processing mill residues
Paper & pulping waste slurries
Municipal garbage & other
landfilled wastes
Municipal Solid Waste
Landfill gas-to-energy
Pre- and post-consumer residues
Urban wood residues
Construction & Demolition wastes
Tree trimmings
Yard waste
Packaging
Discarded furniture
%
U.S. Data
crop residue
animal manure
forest residue
MSW , C&D
Category
(modified from
Perlack et al., 2005)
Crop
residues
Animal
manures
Forest
residues
Landfill
wastes
Millions of
dry tons/yr
U.S. (%)
218.9
43
35.1
7
178.8
35
78
15
%
crop residue
animal manure
forest residue
MSW, C&D
Category
Ohio data
(modified from Jeanty
et al., 2004)
Billions of
BTUs
Ohio (%)
Crop residues
53,717
18
Animal
manures
2,393
1
Forest residues
33,988
12
Landfill wastes
199,707
69
Biomass to Bioenergy
Biomass:
renewable energy sources coming
from biological material such as plants, animals,
microorganisms and municipal wastes
Bioenergy Types
Biofuels
Liquids
Methanol, Ethanol, Butanol, Biodiesel
Gases
Methane, Hydrogen
Bioheat
Wood burning
Bioelectricity
Combustion in Boiler to Turbine
Microbial Fuel Cells (MFCs)
Conversion Processes
Biological conversion
Fermentation (methanol,
ethanol, butanol)
Anaerobic digestion
(methane)
Anaerobic respiration (biobattery)
Chemical conversion
Transesterification
(biodiesel)
Thermal conversion
Combustion
Gasification
Pyrolysis
Biomass-to-Bioenergy Routes
Gasification
Solid biomass
(wood, straw)
Fuel gas
Combustion
Pyrolysis
Pyrolytic oil
Hydrolysis
Oil crops and algae
(sunflower, soybean)
Crushing
Extraction
Refining
Ethanol
Butanol
Sugar
fermentation
Methyl ester
(biodiesel)
Transesterification
Pure Oil
co2
Sugar and starch plants
(sugar-cane, cereals)
Liquid biofuels
6CO2 + 6H2O
Hydrolysis
Heating
fermentation
Biogas
H2, CH4
Electrical devices
Anaerobic
Application
Transport
Wet biomass
(organic waste, manure)
Biofuels and Bioenergy
Heat
Biomass
Electricity
C6H12O6 + 6O2
Photosynthesis
Conversion
processes
Advantages of Biomass
 Widespread availability in many parts of the world
 Contribution to the security of energy supplies
 Generally low fuel cost compared with fossil fuels
 Biomass as a resource can be stored in large
amounts, and bioenergy produced on demand
 Creation of stable jobs, especially in rural areas
 Developing technologies and knowledge base offers
opportunities for technology exports
 Carbon dioxide mitigation and other emission
reductions (SOx, etc.)
Environmental Benefits
Drawbacks of Biomass
Generally low energy content
Competition for the resource with food,
feed, and material applications like
particle board or paper
Generally higher investment costs for
conversion into final energy in
comparison with fossil alternatives
Applications
Biofuel Applications: Liquids
Ethanol and Butanol:
can be used in gasoline engines
either at low blends (up to
10%), in high blends in Flexible
Fuel Vehicles or in pure form in
adapted engines
Biodiesel: can be used, both
blended with fossil diesel and in
pure form. Its acceptance by car
manufacturers is growing
Process for cellulosic bioethanol
 http://www1.eere.energy.gov/biomass/abcs_biofuels.html
Why Butanol?
More similar to gasoline than ethanol
Butanol can:
 Be transported via existing pipelines
(ethanol cannot)
Fuel engines designed for use with gasoline
without modification (ethanol cannot)
Produced from biomass (biobutanol) as
well as petroleum (petrobutanol)
Toxicity issues (no worse than gasoline)
Biodiesel from triglyceride oils
Methoxide
Triglyceride
Methyl Ester
Glycerine
 Triglyceride consists of glycerol backbone + 3 fatty acid tails
 The OH- from the NaOH (or KOH) catalyst facilitates the breaking
of the bonds between fatty acids and glycerol
 Methanol then binds to the free end of the fatty acid to produce a
methyl ester (aka biodiesel)
 Multi-step reaction mechanism: Triglyceride→Diglyceride
→Monoglyceride →Methyl esters+ glycerine
Biodiesel Production
Methanol
Raw Oil
Catalyst NaOH
Crude Biodiesel (methyl ester)
Crude glycerin
Excess methanol
Catalyst KOH
Catalyst Mixing
Transesterification
Reaction
Acid (phosphoric)
Neutralization
Methanol Recovery
Recovered
methanol
Biodiesel,
glycerin
Phase Separation
gravity or centrifuge
Crude Glycerine
Biodiesel,
impurities
Purification
(washing)
Wash water
water
Fertilizer
K3PO3
Fuel Grade
Biodiesel
Biofuel Applications: Gases
Hydrogen: can be used in
fuel cells for generating
electricity
Methane: can be
combusted directly or converted
to ethanol
Bioheat Applications
Small-scale heating systems
for households typically use
firewood or pellets
Medium-scale users typically
burn wood chips in grate
boilers
Large-scale boilers are able to
burn a larger variety of fuels,
including wood waste and
refuse-derived fuel
Biomass Boiler
(for more info: Dr. Harold M. Keener, OSU Wooster, E-mail keener.3@osu.edu)
Bioelectricity Applications
Co-generation:
Combustion followed by a
water vapor cycle driven
turbine engine is the main
technology at present
Microbial Fuel Cells
(MFCs): Direct conversion
of biomass to electricity
Microbial fuel cells (MFCs)
PEM
Electrons flow from an anode through a resistor to a cathode
where electron acceptors are reduced. Protons flow across a
proton exchange membrane (PEM) to complete the circuit.
Bio-electro-chemical devices
Bacteria as biocatalysts convert the
biomass “fuel” directly to electricity
Oxidation-Reduction reaction
switches from normal electron
acceptor (e.g., O2, nitrate, sulfate)
to a solid electron acceptor:
Graphite anode
It’s all about REDOX CHEMISTRY!
Microbial fuel cells in the lab
•Two-compartment MFC
• Proton exchange membrane:
Nafion 117 or Ultrex
• Electrodes: Graphite plate
84 cm2
• Working volume: 400 ml
ANODE
Membrane
Cathode
CATHODE
Anode
Not to Scale
6CO2 + 24e- + 24H+
ee-
2CO2 + 8e- + 8H+
Acetate
n=1
H+
eH+
e-
Glucose
e-
e-
β-Glucan (n ≤7)
H+
n≥2
Propionate
Cellodextrin
Bacteria
Cell Wall
O2
H+
Anode
β-Glucan
(n≤7)
Cathode
Cellulose
3CO2 + 28e- + 28H+
H2O
β- Glucan (n-1)
Proton Exchange
Membrane
Butyrate
Anode
compartment
Bacteria Cell
4CO2 + 18e- + 18H+
Cathode
compartment
My own MFC story
Undergraduate in-class presentation, 2003
 Bond, D.R. Holmes, D.E., Tender L.M., Lovley D.R. 2002. Electrodereducing microorganisms that harvest energy from marine sediments.
Science 295: 483–485.
Extra-curricular student team project, 2004-2005
USEPA - P3 first round winner 2005
#1 in ASABE’s Gunlogson National Competition 2005
Research program, 2005 to present
3 Ph.D. students, 2 undergrad honors theses, 4 faculty
Over $200,000 in grant funding
High school science class project online resource
http://digitalunion.osu.edu/r2/summer07/nskrinak/index.html
References

Ezeji, T., N. Qureshi, H.P. Blaschek. 2007. Butanol production from agricultural residues: Impact of
degradation products on Clostridum beijerinckii growth and butanol fermentation. Biotechnol.
Bioeng. 97, 1460-1469.

Jeanty, P.W., D. Warren, and F. Hitzhusen. 2004. Assessing Ohio’s biomass resources for energy
potential using GIS. OSU Dept of Ag, Env., and Development Economics, for Ohio Dept of
Development.
http://www.puc.state.oh.us/emplibrary/files/media/biomass/bioenergyresourceassessment.pdf

Klass, Donald L. 1998. Biomass for Renewable Energy, Fuels, and Chemicals. Academic Press.
ISBN: 9780124109506.

Perlack et al. 2005. Biomass as feedstock for a bioenergy and bioproducts industry: The technical
feasibility of a billion-ton annual supply. USDOE-USDA.
http://www.puc.state.oh.us/emplibrary/files/media/biomass/BiomassFeedstock.pdf

Rabaey, K., Verstraete, W. 2005. Microbial fuel cells: Novel biotechnology for energy generation.
Trends. Biotechnol. 23:291-298.

Rismani-Yazdi, H., Christy, A. D., Dehority, B.A., Morrison, M., Yu, Z. and Tuovinen, O. H. 2007.
Electricity generation from cellulose by rumen microorganisms in microbial fuel cells. Biotechnol.
Bioeng. 97, 1398-1407.

Skrinak, N. 2007. OSU Microbial Fuel Cell Learning Center
<http://digitalunion.osu.edu/r2/summer07/nskrinak/index.html>

USDOE Biomass Program. ABCs of Biofuels
<http://www1.eere.energy.gov/biomass/abcs_biofuels.html>. Accessed April 2008.
For more info
(or to request reference list)
Ann D. Christy, Ph.D., P.E.
Associate Professor
Dept of Food, Agricultural, and
Biological Engineering
614-292-3171
Email: christy.14@osu.edu