1. “Topics in Bioenergy, Bioprocessing, and Biofuels” PSE 490/CFR 523
Spring 2008

2. Agenda
Bioenergy
Rice Krispies Treats
Biomass chemistry

3. Your co-instructor: Renata Bura
B.Sc.,1997, Ryerson University, Toronto, Canada, Chemistry
M.A.Sc., 2000, University of Toronto, Chemical Engineering and Applied Science and Environmental Engineering
Ph.D., 2004, University of British Columbia, Vancouver, Canada, Forestry
Post Doc., 2006, UBC, Vancouver, Canada
2006, joined UW-Assistant Professor in Natural Products Chemistry

4. Biofuels and biochemicals
Biological
Biofuels
Biochemicals
Biomass
Thermochemical

5. What is Bioconversion?
General: a process which uses biological agents (microorganisms or protein) to transform a feedstock into desirable products.
Bioethanol
A chemical/biochemical process by which lignocellulosic materials are converted to ethanol and other co-products.

6. Why Bioconversion? Energy Air pollution Waste elimination
An alternative source of energy for the transportation sector produced locally
Air pollution
Reduction in greenhouse gas emissions
Waste elimination
Elimination of problems with field burning/incineration, stockpiling, etc.
Socio/economical benefits
Creation of new jobs, rural development

7. Fundamentals of wood chemistry
Cellulose
Hemicellulose
Lignin

8. Bioethanol from sugar cane
Energy balance
History
Problems
Production

9. Bioethanol from corn Corn to ethanol Energy balance Problems
Production
Dry milling
Wet milling

10. Bioethanol from lignocellulosic biomass
Feedstock diversity
Pretreatment
Hydrolysis
Fermentation

11. Biodiesel Why biodiesel? How to make it? Biodiesel and cars
Possible sources
Biodiesel and cars

12. How is Biomass like a Kellogs™ Rice Krispies Treat?
Your warped instructor needed some sort of an analogy to assist people in understanding biomass.
This is it.
Image borrowed from Kellogs™ web site for academic purposes

13. Rice Krispies Alone
At my home, a box of Rice Krispies consists of 2 things: Rice Krispies and Rice Krispies dust.
You can pour this mixture into a bowl but you cannot stand it up or make a bar.
Image borrowed from Kellogs™ web site for academic purposes

14. Formation of the Bar
In order to make a solid bar, you need something to glue together the Rice Krispies and the Rice Krispies dust.
Marshmallow cooked over an open flame works great.
You also need something to preserve the bars….A variety of preservatives can be used.

15. Rice Krispies Treats
The butter and the marshmallows are heated together forming a sticky glue type material.
This is applied to the Rice Krispies and dust forming a bar which is solid when cooled.

16. What is Cellulose?
Cellulose is a large molecule made from glucose molecules (dextrose) strung together like beads on a string.
The glucose molecules are known as monomers and the cellulose chain is known as a polymer.
1 glucose molecule= monomer
2 linked glucose molecules= dimer
3 linked glucose molecules= trimer
lots of linked glucose molecules = polymer

17. What is Cellulose?
Cellulose is straight chain polymer. In bead terms, imagine a very very long straight string of beads with 2 ends and no branching points.
In wood, cellulose chains contain typically 10,000 glucose molecules…quite a long sting of beads.
Source: World Book Encycopedia

18. Cellulose
Very long straight chain polymer of glucose (a sugar): approximately 10,000 in a row in wood. Cotton is nearly pure cellulose.
Think about a very long string of beads with each bead being a glucose molecule.
Cellulose molecules link up in bundles and bundles of bundles and bundles of bundles of bundles to make fibers.
Uncolored polymer.

19. What are Hemicelluloses?
Hemicelluloses are also sugar polymers but different from cellulose because they are:
Made up glucose and other sugars.
Contain some molecules other than sugars.
Branched little polymers
Much smaller than cellulose as they are made up of between sugars (Rice Krispies Dust)
There are lots of varieties of hemicelluloses.

20. Hemicelluloses
Branched little uncolored sugar polymers (~ 50 to 300 sugar units)
Composition varies between wood species.
5 carbon sugars: xylose, arabinose.
6 carbon sugars: mannose, galactose, glucose.
Uronic Acids: galacturonic acid, glucuronic acid.
Acetyl and methoxyl groups (acetic acid & methanol).
Major hemicelluloses:
Xylans - big in hardwoods
Glucomannans: big in softwoods
Minor hemicelluloses: pectins, others.

21. Xylan Structure
4--D-Xly-14--D-Xly-14--D-Xly-14--D-Xly4--D-Xly      
4-O-Me--D-Glc  
-L-Araf 

22. Glucomannan Structure
14--D-Glc-14--D-Man-14--D-Man-14--D-Man-1
2,3 
Acetyl 6
-D-Gal 1
There are different structured glucomannans in hardwoods and softwoods (and within softwoods)
Glucomannans are mostly straight chained polymers with a slight amount of branching. The higher the branching, the higher the water solubility.

23. What is Lignin?
Lignin is a polymer like cellulose and hemicelluloses but is made with phenolic compounds (aromatic rings) instead of sugars.
Lignins are large 3 dimensional polymers that form the glue that holds the cellulose and hemicelluloses together.
Picture taken from Katy’s chicken page.
Lignin has been described as 3 dimensional chicken wire.

24. Lignin Phenolic polymer - the glue that holds the fibers together.
Lignin is a very complex polymer which is connected through a variety of different types of linkages.
Colored material.

25. What are Extractives?
In the Rice Krispies model, extractives compounds were represented by preservatives added to the treats. This is a very good representation of the role of a good portion of the extractives in trees.
The term extractives refers to a large variety of different chemicals produced by the tree for a variety of reasons (protection, food storage, formation of membranes, color, etc.).
Examples: what sticks to your hand when you pick up your Christmas tree, what comes out of your tea bag with hot water.

26. Extractives In some tropical species this can be as high as 25%.
The term extractives refers to a group of unique chemical compounds which can be removed from plant materials through extraction with various solvents.
Typically these chemicals constitute only a small portion of the tree (<5%).
In some tropical species this can be as high as 25%.
Extractives are produced by plants for a variety of uses.
The most common use by plants is protection.
Extractives can cause serious problems for processing.
Pitch is a term which is often used when describing some groups of extractives.
Extractives are responsible for the characteristic color and odor of wood.

27. Putting it All Together
Putting all of the components together and you get biomass. The cellulose and the hemicelluloses held together with lignin.
Taking the lignin away through chemical processes (pulping and bleaching) leaves these fibers of cellulose and hemicelluloses.
Picture from Focus Forest Products Web Site

28. What is the Chemical Makeup of Wood?
* Data for Cellulose, Hemicellulose & Lignin on extractive free wood basis