1. Chip Chat: Oct 2017 Solar-energy driven bioethanol production

2. Biofuels
Fuel that is produced through contemporary biological processes
Biofuels currently in use
Bioethanol (corn, cellulose, sugarcane)
Biodiesel (from rapeseed and soybeans)
Others: Bioethers, Syngas, Solid biomass fuels

3. Lifecycle: Bioethanol versus Petrol

4. Bioethanol Production

5. Bioethanol production
Feedstock Supply: Feedstocks for biochemical processes are selected for optimum composition, quality, and size. Feedstock handling systems tailored to biochemical processing are essential to cost-effective, high-yield operations.
B. Pretreatment: Biomass is heated (often combined with an acid or base) to break the tough, fibrous cell walls down and make the cellulose and hemicellulose easier to hydrolyze (see next step).
C. Hydrolysis: Enzymes (or other catalysts) enable the sugars within cellulose and hemicellulose in the pretreated material to be separated and released over a period of several days.
D1. Biological Conversion: Microorganisms are added, which then use the sugars to generate other molecules suitable for use as fuels or building-block chemicals.
D2. Chemical Conversion: Alternatively, the sugars can be converted to fuels or an entire suite of other useful products using chemical catalysis.
E. Product Recovery: Products are separated from water, solvents, and any residual solids.
F. Product Distribution: Fuels are transported to blending facilities, while other products and intermediates may be sent to traditional refineries or processing facilities for use in a diverse slate of consumer products.
G. Heat & Power: The remaining solids are composed primarily of lignin, which can be burned for heat and power.

6. Principle of fermentation
Summarizing chemical equation for ethanol fermentation:
C6H12O6 → 2 C2H5OH + 2 CO2
One glucose molecule is converted into two ethanol molecules and two carbondioxide molecules.

7. Bioethanol Feedstocks

8. First/Second generation
First generation versus second generation
First generation ethanol, commonly known simply as ‘‘ethanol’’, is a biofuel produced by the fermentation and distillation of sugar- and starch- based raw materials
Ethanol from non-edible sources (such as corn stover and sugarcane bagasse) is termed ‘‘second generation ethanol’’, or bioethanol.
Large quantities of ethanol is a fermentation inhibitor, therefore molasses have to be diluted

9. Ethanol feedstocks: Starch
Eg. Corn
Easy to extract and ferment
Food versus Fuel
Ubiquitous availability- save transportation costs

10. Ethanol Feedstocks: Cellulose/Lignocellulose
Most common organic compound on earth
Found in non-food plant material such as agricultural wastes
Considered a “second generation” biofuel, therefore starts comparing to current biofuels
Ubiquitous availability- save transportation costs
Straw, grasses and wood
the issue of transport for cellulosic feedstocks is not as large as it is for corn, due to the fact that cellulosic production in more regions of the country is possible, thus reducing shipment costs.
From farm to car, cellulosic ethanol releases less greenhouse gas than gasoline (86 percent less) and corn ethanol (52 percent less than gasoline)
Lignocellulosic agricultural residues are an ideal choice since they can be effectively hydrolyzed to fermentable sugars and integrated in the context of a biorefinery without competing with the food supply chain
From an environmental point of view, ethanol can reduce sulphur, particulate matter and carbon monoxide emissions, but it may increase atmospheric concentrations of acetaldehyde (CH3CHO), a chemical precursor in the formation of photochemical smog.
Additionally, the carbon footprint from ethanol combustion is smaller than that produced by fossil fuels, since plants remove carbon from the environment to produce biomass
Compared to corn, cellulosic feedstocks have better energy conversion ratios, cause reduced CO2 emissions, and create less damaging land and water impacts
Net positive/negative: Corn- debateable, cellulose: slightly less debateable, biodiesel: positive established (The reason is due mainly to the natural ability of soybeans to fix nitrogen)
Costliest input to corn-based ethanol production is nitrogen fertilizer. Soybeans can be grown without, leave the soil nitrogen rich beneficial to follow on crops

11. Lignocellulose

12. Plant cell wall components
Cellulose
Cellulose
Lignin
Lignin
Hemicellulose
(need special yeast to convert to ethanol)
Extractives
Extractives
Ash
Ash
Chapple, 2006; Ladisch, 1979

13. Lignocellulosic biomass
Cellulose
Lignin
Pretreatment
Hemicellulose
Amorphous Region
Crystalline Region

14. Ethanol Feedstocks: Marine Algae
High growth rates and productivity
Low energy demand
High carbohydrate content
Do not compete with the cultivation of food crops or freshwater supply
Nor adversely affect vulnerable ecosystems
Able to sustain hostile environments including insufficient nutrients and high salinity.

15. Comparisons

16. Barriers to cellulosic ethanol production
Refining and production costs
Acreage dedicated to growing switchgrass is acreage not dedicated to growing food.
Fortunately, enzymes to separate lignin from cellulose
This process converts 45% of the biomass energy into ethanol (85% for oil)

17. Comparison of feedstocks: Potential Yield

18. Comparison of feedstocks: Ethanol types and gasoline

19. Bioethanol Properties

20. Bioethanol versus biodiesel

21. Current Methodologies

22. Current Methodologies for bioethanol production
Feedstock improvement
Pretreatment: Ultrasonication and microwave irradiation
Shortening of fermentation time
Lowering the enzyme dosages
Improving the overall starch hydrolysis
Integration of the simultaneous saccharification and fermentation (SSF) process

23. Different Production Setups

24. Different Production Setups

25. Solar-energy driven catalytic reaction
Single-step conversion
Starch, cellulose, marine algae as feedstock

26. Solar-energy driven catalytic reaction: Algae

27. Solar-energy driven catalytic reaction

28. Solar-energy driven catalytic reaction
About 65 day incubation
0.6 g ethanol per day, 8 g ethanol per m2 per day
38 gm of ethanol at the end
85% theoretical yield

29. Bioethanol: Pros and Cons

30. Bioethanol: Pros Renewable Complete combustion, cleaner burning
Reduction in GHGs
Carbon neutral
Energy security
Better management of spills

31. Bioethanol: Cons
Hygroscopic nature
Shipping costs (lack of pipeline system)
Corn prices are influenced by the converging demands (food vs fuel)
Ethanol more expensive than gasoline on a per gallon basis
Lower energy content
Can only be used on a specially designed vehicles
Lack of availability of E-85 pumping stations.
Strain on agricultural production and land use, depletes fresh water supplies and soil resources
Distribution hampered by a high level of corrosiveness damaging existing infrastructure
May increase atmospheric concentrations of acetaldehyde
The production of ethanol places an enormous strain on agricultural production and land use, depletes fresh water supplies and soil resources
Distribution of ethanol is hampered by a high level of corrosiveness that damages existing infrastructure
Without subsidies, ethanol costs more to produce than gasoline
There is a strong body of conflicting data with regard to its net energy output
Ethanol’s potential contribution to greenhouse gas impacts are debatable

32. Questions:
Is burning biofuels more environmentally-friendly than burning oil?
What are the alternatives for a more sustainable energy system?
What are the ways bioethanol production and usage can be improved?
What are the incentives for better engine design to incorporate ethanol as fuel?
Ways to dry bioethanol to increase purity?

33. GreenChem UBC Questions? gcubc@chem.ubc.ca
We have a sign-up sheet…questions…you can contact us at these addresses

34. Questions:

35. Failures of bioethanol

36. Failures of bioethanol

37. Failures of bioethanol

38. Failures of bioethanol

39. Different Production Setups

40. Different Production Setups

41. Outline What is bioethanol
Different sugar sources: Starch, cellulose, lignocellulose, algae
General process of bioethanol production: saccharification, fermentation
Reactor sketch
First/second generation
Bioethanol advantages
Bioethanol disadvantages
Comparison of different kinds of ethanol and gasoline

42. Cellulosic versus lignocellulosic/hemicellulosic
Cellulose is hydrolyzed to glucose, while hemicellulose is decomposed mainly into xylose and other pentoses and hexoses (Figure 2). The hydrolysis of agricultural residues can be achieved by the addition of acid, base or enzymatic catalysts.
Need for neutralizing the reaction medium after the process, the high corrosivity and the generation of solid wastes and the generation of degradation products such as acetic acid and furfural