1. Bioethanol
Bioethanol is produced from plants (biomass) that harness the power of the sun to convert water and CO2 to sugars (photosynthesis).
Biomass like corn
are finely ground
and separated into their component sugars
The sugars are distilled to make ethanol.
Ethanol can be used as a fuel
Combustion releases CO2
CO2 is reabsorbed by the biomass when growing it
Prof. R. Shanthini Jan 28, 2012

2. Bioethanol
Bioethanol is produced from plants (biomass) that harness the power of the sun to convert water and CO2 to sugars (photosynthesis).
Prof. R. Shanthini Jan 28, 2012

3. Biomass What is it made up of?
- The major constituent of biomass is carbohydrates, which are composed of carbon (C), hydrogen (H) and oxygen (O).
- Carbohydrates are represented by Cx(H2O)n.
Prof. R. Shanthini Jan 28, 2012

4. Biomass What is it made up of?
Monosaccharide (known as simple sugars) is the simplest form of a carbohydrate.
They have the general formula (CH2O)n where n = 3 to 7 .
Examples: glucose, fructose and galactose (all are n = 6).
(CH2O)6 or
C6H12O6
Prof. R. Shanthini Jan 28, 2012

5. Biomass What is it made up of? Prof. R. Shanthini Jan 28, 2012

6. Biomass What is it made up of?
Disaccharides are formed by joining 2 monosaccharide molecules.
Examples:
- Maltose is formed by two glucose molecules. It occurs in cells as a breakdown product of starch. It is also formed in the seeds during germination. It is commonly called malt sugar.
Lactose is found in milk and hence commonly called milk sugar. It is formed by condensation of a glucose molecule and a galactose molecule.
Sucrose is found extensively in plants. It is commonly called cane sugar. It is formed by condensation of a glucose molecule and a fructose molecule.
C6H12O6
+ C6H12O6
C12H22O11
+ H2O
Prof. R. Shanthini Jan 28, 2012

7. Biomass What is it made up of? Prof. R. Shanthini Jan 28, 2012

8. Biomass What is it made up of?
Polysaccharides are composed of three or more monosaccharides.
- The two primary polysaccharides are starch and cellulose.
- Both starch and cellulose are composed of glucose units.
- The primary difference between the two is the linkage of their units.
Prof. R. Shanthini Jan 28, 2012

9. Biomass What is it made up of? alpha-glucose beta-glucose
Prof. R. Shanthini Jan 28, 2012

10. Biomass What is it made up of?
- The glucose molecules in starch are linked via alpha linkages, which may be broken by both mammalian and microbial enzymes.
The glucose molecules in cellulose are linked via beta linkages, which may be broken by only microbial enzymes.
Prof. R. Shanthini Jan 28, 2012

11. Bioethanol What is it made up of?
- Cellulose is 40 to 60% by weight of most biomass
Cellulose is made from several hundred to over ten thousand glucose units
Cellulose has the formula (C6H10O5)n
The crystalline structure of cellulose makes it resistant to hydrolysis (the chemical reaction that converts cellulose into glucose).
Prof. R. Shanthini Jan 28, 2012

12. Biomass What is it made up of?
- Other carbohydrates include pectins and hemicellulose.
- Pectins and hemicellulose are only digested and utilized by microbes.
Prof. R. Shanthini Jan 28, 2012

13. Bioethanol What is it made up of?
- Hemicellulose is 20 to 40% by weight of most biomass
- It is made mainly from the five-carbon sugar, xylose.
Xylose
Prof. R. Shanthini Jan 28, 2012

14. Biomass What is it made up of? Lignin is an essential part of biomass.
- It is not a carbohydrate.
- Chemically, lignin is a polyphenolic polymer.
- Lignin is associated with fibrous feedstuffs, and is indigestible by both microbial and mammalian enzymes.
- As a plant matures lignin content increases.
Prof. R. Shanthini Jan 28, 2012

15. Biomass What is it made up of?
Lignin is 10 to 24% by weight of biomass.
It is a complex polymer, which provides structural integrity in plants.
- It remains as residual material after the sugars in the biomass have been converted to ethanol.
- It contains a lot of energy and can be burned to produce steam and electricity for the biomass-to-ethanol process.
Prof. R. Shanthini Jan 28, 2012

16. Bioethanol It is simply ethanol Ethanol formation from glucose: yeast
C6H12O6
2 C2H5OH
+ 2 CO heat
glucose ethanol carbon
dioxide
180 g g g kcal
1 kg g g kcal
Prof. R. Shanthini Jan 28, 2012

17. Bioethanol It is simply ethanol Ethanol combustion: C2H5OH + 3 O2
2 CO H2O + heat
ethanol
Heat released is 1020 kJ/mol
Prof. R. Shanthini Jan 28, 2012

18. Bioethanol
oxygen in the ethanol molecule helps in complete combustion, which means less emissions
Prof. R. Shanthini Jan 28, 2012

19. Bioethanol
Ethanol is a high-octane fuel, and is widely used as a blending ingredient in petrol.
The octane rating is a measure of how likely a gasoline or liquid petroleum fuel is to self ignite. The higher the number, the less likely an engine is to pre-ignite and suffer damage.
Prof. R. Shanthini Jan 28, 2012

20. Bioethanol
A growing number of cars and trucks designated as FlexFuel Vehicles (FFV) can use ethanol blended up to 85% with petrol (E85 fuel).
Today there are more than 6 million FFV's on U.S. roads alone.
Prof. R. Shanthini Jan 28, 2012

21. Bioethanol
Prof. R. Shanthini Jan 28, 2012
Source:

22. Bioethanol 2 C2H5OH + 2 CO2 yeast Bioethanol from simple sugars:
Sugar cane and sugar beets store the energy as simple sugars, glucose (C6H12O6)
glucose molecule
yeast
2 C2H5OH
+ 2 CO2
this simple-looking reaction is a bioreaction and thus very complex
impure cultures of yeast produce glycerine and various organic acids
Prof. R. Shanthini Jan 28, 2012

23. Bioethanol Yeast can be replaced by the bacterium Zymomonas mobilis
- gives up to 98% yields
- minimal by-products
- simple fermentation requirements
- several-fold the production rates of yeast
Z. mobilis industrial strain CP4,
originating from Brazil,
vigorously fermenting glucose.
Photo courtesy Katherine M. Pappas
Prof. R. Shanthini Jan 28, 2012

24. Bioethanol Bioethanol from simple sugars: sugar cane residue (bagasse)
sugar cane crushed and soluble sugar washed out
yeast / bacteria
soluble sugar for fermentation
CO2
5 - 12% ethanol
distilled to concentrate to 80 – 95% ethanol
dehydrate to 100% ethanol
can’t be used as petrol additive but as petrol replacement
can be used as petrol additive
Prof. R. Shanthini Jan 28, 2012
Dehydration in an expensive process

25. Amyloglucosidase enzyme
Bioethanol
Bioethanol from starch:
Corn, wheat and cassava store the energy as more complex sugars, called starch. }
starch
(glucose polymer)
alpha-amylase enzyme
dextrins
Amyloglucosidase enzyme
glucose monomer
Prof. R. Shanthini Jan 28, 2012

26. Bioethanol 80-95% ethanol 100% ethanol Bioethanol from starch:
Liquification
(at 90 – 95 deg C;
pH = ; 400 rpm)
corn flour + water + alpha-amylase enzyme
Saccharification with glucosidase enzyme
(at deg C, pH = )
Fermentation
(40 – 50 hrs)
Cooling (32 deg C)
Distillation
Dehydration
80-95% ethanol
100% ethanol
Prof. R. Shanthini Jan 28, 2012

27. Bioethanol Bioethanol from starch:
Dry grind process is the most common method used to make fuel grade ethanol.
The whole corn kernel is ground and converted into ethanol.
It is relatively cost effective and requires less equipment, but is not ideal for mass producing. 
Prof. R. Shanthini Jan 28, 2012

28. Bioethanol Bioethanol from starch:
In the wet milling process, corn is separated into its four basic components:
starch,
germ,
fiber, and
protein,
which are each made into different products.
Advantage: valuable co-products such as corn oil
Disadvantages: equipment is expensive and the process uses hazardous sulfur dioxide
Prof. R. Shanthini Jan 28, 2012

29. Bioethanol Bioethanol from biomass (other than sugars and starches):
Rice straw
Paddy husks
Saw dust
Grasses
Bagasse
Prof. R. Shanthini Jan 28, 2012

30. Bioethanol Bioethanol from biomass (other than sugars and starches):
- Cellulose is 40 to 60% by weight of most biomass
Cellulose is made from several hundred to over ten thousand glucose units
The crystalline structure of cellulose makes it resistant to hydrolysis (the chemical reaction that converts cellulose into simple, fermentable glucose).
Prof. R. Shanthini Jan 28, 2012

31. Bioethanol Bioethanol from biomass (other than sugars and starches):
- Hemicellulose is 20 to 40% by weight of most biomass
- It is made mainly from the five-carbon sugar, xylose.
- Its relatively easy to hydrolyze hemicellulose into simple sugars but normal yeast can't ferment xylose.
- Celunol Corp. has acquired genetically engineered E. coli bacteria which can turn almost all xylose into ethanol.
Xylose
Prof. R. Shanthini Jan 28, 2012

32. Prof. R. Shanthini Jan 28, 2012

33. Bioethanol Bioethanol from biomass (other than sugars and starches):
Obstacles to commercial production of cellulosic ethanol:
Accelerating the breakdown of
cellulose fibers
Research on acid / enzymatic hydrolysis is ongoing.
Lignin waste problem
Lignin can fuel Combined Heat and Power plants, however, CHP plants are expensive.
Use of genetically modified (GM) microorganisms
Prof. R. Shanthini Jan 28, 2012
Source: DOE's 2006 Annual Energy Outlook

34. Bioethanol
A cellulosic ethanol plant with 50 million gallons per year capacity and a lignin-fired will cost about $300 million to build.
A corn ethanol plant with the same capacity could be built for about $65 million.        
Prof. R. Shanthini Jan 28, 2012
Source: DOE's 2006 Annual Energy Outlook

35. Bioethanol
Currently, ethanol yields 25% more energy output than input to produce it.
Research is on for less costly ways of producing ethanol, and better ways to blend it with petrol.
Prof. R. Shanthini Jan 28, 2012

36. Bioethanol
Bioethanol will be used in engines that convert heat into work
Engines that convert heat into work are very inefficient
Prof. R. Shanthini Jan 28, 2012

37. Bioethanol
We throwaway energy that rightfully belong to the future generations.
“Development that meets the needs of the present without compromising the ability of future generations to meet their own needs."
Our Common Future (1987)
Prof. R. Shanthini Jan 28, 2012

38. Bioethanol Water Requirements for
Energy Production by different process
Bioethanol
Process Litre/MWh
petroleum extraction
oil refining
oil shale surface retort
NGCC power plant, closed loop cooling ,300
coal IGCC ≈ 900
nuclear power plant, closed loop cooling ≈ 950
geothermal power plant, closed loop tower
NGCC: Natural gas combined cycle
IGCC: Integrated gasification combined-cycle
Energy Demands on Water Resources; Report to Congress on the
Interdependency of Energy and Water; U.S. Department of
Energy: Washington, DC, 2006; p 80.
Prof. R. Shanthini Jan 28, 2012

39. Bioethanol Water Requirements for
Energy Production by different process
Bioethanol
Process Litre/MWh
Enhanced oil recovery ≈ 7600
NGCC, open loop cooling 28,400 75,700
nuclear power plant, open loop cooling 94, ,100
corn ethanol irrigation 2,270, ,670,000
soybean biodiesel irrigation 13,900, ,900,000
NGCC: Natural gas combined cycle
IGCC: Integrated gasification combined-cycle
Energy Demands on Water Resources; Report to Congress on the
Interdependency of Energy and Water; U.S. Department of
Energy: Washington, DC, 2006; p 80.
Prof. R. Shanthini Jan 28, 2012

40. Bioethanol Water Requirements for
Energy Production by different process
Bioethanol
Process Litre/MWh
petroleum extraction + oil refining
nuclear power plant, closed loop cooling ≈ 950
nuclear power plant, open loop cooling 94, ,100
corn ethanol irrigation 2,270, ,670,000
soybean biodiesel irrigation 13,900, ,900,000
In summary
Energy Demands on Water Resources; Report to Congress on the
Interdependency of Energy and Water; U.S. Department of
Energy: Washington, DC, 2006; p 80.
Prof. R. Shanthini Jan 28, 2012