1. Bioethanol

2. CONTENTS What is bioethanol? Bioethanol Production Fuel Properties
Application
Advantages
Disadvantages and Concerns
Ethanol Controversy
Comparison of Bioethanol and Biodiesel
Future development

3. What is Bioethanol
Bioethanol is an alcohol made by fermentation, mostly from carbohydrates produced in sugar or starch crops such as corn or sugarcane. Cellulosic biomass, derived from non-food sources such as trees and grasses, is also being developed as a feedstock for ethanol production

4. The principle fuel used as a petrol substitute is bioethanol
Bioethanol fuel is mainly produced by the sugar or cellulose fermentation process
Ethanol is a high octane fuel and has replaced lead as an octane enhancer in petrol
Bioethanol is an alternative to gasoline for flexifuel vehicles

5. Wheat/Grains/Corn/Sugar-cane can be used to produce ethanol
Wheat/Grains/Corn/Sugar-cane can be used to produce ethanol. (Basically, any plants that composed largely of sugars)
Bioethanol is mainly produced in three ways.
Sugar > ethanol
starch > sugar > ethanol
cellulose and hemicellulose > ethanol

6. Processes for Bioethanol Production
1. Concentrated Acid Hydrolysis
~77% of sulfuric acid is added to the dried biomass to a 10% moisture content.
Acid to be added in the ratio of 1/25 acid :1 biomass under 50°C. 
Dilute the acid to ~30% with water and reheat the mixture at100°C for an hour.
Gel will be produced and pressed to discharge the acid sugar mixture.
Separate the acid & sugar mixture by using a chromatographic column .

7. 2. Dilute Acid Hydrolysis
oldest, simplest yet efficient method
hydrolyse the bio-mass to sucrose
hemi-cellulose undergo hydrolysis with the addition of 7% of sulfuric acid under the temperature 190°C.
to generate the more resistant cellulose portion, 4% of sulfuric acid is added at the temperature of 215°C

8. 3. Wet milling process
corn kernel is soaked in warm water
proteins broken down
starch present in the corn is released (thus, softening the kernel for the milling process)
microorganisms, fibre and starch products are produced.
In the distillation process, ethanol is produced.

9. 4. Dry milling process
Clean and break down the corn kernel into fine particles
Sugar solution is produced when the powder mixture (corn germ/starch and fibre) is broken down into sucrose by dilute acid or enzymes.
Yeast is added to ferment the cooled mixture into ethanol.

10. 5. Sugar fermentation
Hydrolysis process breaks down the biomass cellulosic portion into sugar solutions which will then be fermented into ethanol.
Yeast is added and heated to the solution.
Invertase acts as a catalyst and convert the sucrose sugars into glucose and fructose. (both C6H12O6).

12. 6. Fractional Distillation Process
After the sugar fermentation process, the ethanol still does contain a significant quantity of water which have to be removed.
In the distillation process, both the water and ethanol mixture are boiled.
Ethanol has a lower boiling point than water, therefore ethanol will be converted into the vapour state first  condensed and separated from water.

13. Feedstocks 1. Sugar is required to produce ethanol by fermentation.
Plant materials (grain, stems and leaves) are composed mainly of sugars
almost any plants can serve as feedstock for ethanol manufacture
Crops used in Bioethanol production
Brazil
sugar cane
USA
corn
India
Europe
sugar cane wheat and barley

14. 2. Choice of raw material depends on several factors
ease of processing of the various plants available
prevailing conditions of climate
landscape and soil composition
sugar content

15. 3. R&D activities on using lignocellulosic (woody
materials) as feedstock
Lignocellulosic biomass is more abundant and less expensive than food crops
higher net energy balance
accrue up to 90% in greenhouse gas savings, much higher than the first generation of biofuel
However, more difficult to convert to sugars due to their relatively inaccessible molecular structure

16. Conversion of starch to sugar and then sugar to ethanol
Eg:-1) wheat
Fermentation conditions
Temperature - 32˚C and 35˚C pH
Ethanol is produced at 10-15% concentration and the solution is distilled to produce ethanol at higher concentrations

17. Eg:- 2) sugar cane Simplest of all the processes
Fermentation conditions are similar to the previous slide

18. Ethanol can be produced from a variety of feedstocks such as sugar cane, bagasse, sugar beet, switchgrass, potatoes, fruit, molasses corn, stover, wheat, straw, other biomass, as well as many types of cellulose waste and harvestings
Agricultural feedstocks are considered renewable because they get energy from the sun using photosynthesis
Cornfield in South Africa
Sugar cane harvest
Switchgrass

19. Direct conversion of sugar to ethanol
This is usually done using molasses.
Molasses is a thick dark syrup produced by boiling down juice from sugarcane; specially during sugar refining.
As molasses is a by product, ethanol production from molasses is not done in a large scale around the world.
The main reaction involved is fermentation
yeast
C6H12O6
sugar (e.g.:-glucose)
2 C2H5OH
ethanol +
2 CO2
carbon dioxide

20. The top five ethanol producers in 2010
Brazil billion liters
The United States billion liters
China billion liters
The European Union billion liters
India billion liters

21. Bioethanol Properties
Colourless and clear liquid
Used to substitute petrol fuel for road transport vehicles
One of the widely used alternative automotive fuel in the world (Brazil & U.S.A are the largest ethanol producers)
Much more environmentally friendly
Lower toxicity level

22. Fuel Properties Energy content
Bioethanol has much lower energy content than gasoline
about two-third of the energy content of gasoline on a volume base

23. Fuel Properties
Gasoline
Bioethanol
Molecular weight [kg/kmol]
111 46
Density [kg/l] at 15⁰C
0.75
Oxygen content [wt-%]
34.8
Lower Calorific Value [MJ/kg] at 15ºC
41.3
26.4
Lower Calorific Value [MJ/l] at 15ºC 31
21.2
Octane number (RON) 97
109
Octane number (MON) 86 92
Cetane number 8 11
Stoichiometric air/fuel ratio [kg air/kg fuel]
14.7
9.0
Boiling temperature [ºC]
30-190 78
Reid Vapour Pressure [kPa] at 15ºC 75
16.5

24. Reid vapour pressure (measure for the volatility of a fuel)
Very low for ethanol, indicates a slow evaporation
Adv: the concentration of evaporative emissions in the air remains relatively low, reduces the risk of explosions
Disadv: low vapour pressure of ethanol -> Cold start difficulties
engines using ethanol cannot be started at temp < 20ºC w/o aids

25. Octane number
Octane number of ethanol is higher than petrol
hence ethanol has better antiknock characteristics
increases the fuel efficiency of the engine
oxygen content of ethanol also leads to a higher efficiency, which results in a cleaner combustion process at relatively low temperatures

26. Application transport fuel to replace gasoline
fuel for power generation by thermal combustion
fuel for fuel cells by thermochemical reaction
fuel in cogeneration systems
feedstock in the chemicals industry

27. Blending of ethanol with a small proportion of a volatile fuel such as gasoline -> more cost effective
Various mixture of bioethanol with gasoline or diesel fuels
E5G to E26G (5-26% ethanol, 95-74% gasoline)
E85G (85% ethanol, 15% gasoline)
E15D (15% ethanol, 85% diesel)
E95D (95% ethanol, 5% water, with ignition improver)

28. Advantages Greenhouse gases reduce
Exhaust gases of ethanol are much cleaner
it burns more cleanly as a result of more complete combustion
Greenhouse gases reduce
ethanol-blended fuels such as E85 (85% ethanol and 15% gasoline) reduce up to 37.1% of GHGs
Positive energy balance, depending on the type of raw stock
output of energy during the production is more than the input
Any plant can be use for production of bioethanol
it only has to contain sugar and starch
Carbon neutral
the CO2 released in the bioethanol production process is the same amount as the one the crops previously absorbed during photosynthesis

29. Decrease in ozone formation
The emissions produced by burning ethanol are less reactive with sunlight than those produced by burning gasoline, which results in a lower potential for forming ozone
Renewable energy resource
result of conversion of the sun's energy into usable energy
Photosynthesis -> feedstocks grow -> processed into ethanol
Energy security
esp. Countries that do not have access to crude oil resources
grow crops for energy use and gain some economic freedom
Reduces the amount of high-octane additives
Fuel spills are more easily biodegraded or diluted to non toxic concentrations

30. Disadvantages and Concerns
Biodiversity
A large amount of arable land is required to grow crops, natural habitats would be destroyed
Food vs. Fuel debate
due to the lucrative prices of bioethanol some farmers may sacrifice food crops for biofuel production which will increase food prices around the world
Carbon emissions (controversial)
During production of bioethanol, huge amount of carbon dioxide is released
Emission of GHGs from production of bioethanol is comparable to the emissions of internal-combustion engines

31. Not as efficient as petroleum
energy content of the petrol is much higher than bioethanol
its energy content is 70% of that of petrol
Engines made for working on Bioethanol cannot be used for petrol or diesel
Due to high octane number of bioethanol, they can be burned in the engines with much higher compression ratio
Used of phosphorous and nitrogen in the production
negative effect on the environment
Cold start difficulties
pure ethanol is difficult to vaporise

32. Transportation
ethanol is hygroscopic, it absorbs water from the air and thus has high corrosion aggressiveness
Can only be transported by auto transport or railroad
Many older cars unequipped to handle even 10% ethanol
Negatively affect electric fuel pumps by increasing internal wear and undesirable spark generation

33. Ethanol Controversy

34. Is it justifiable?
..to use agriculture land to grow energy crops instead of food crops when there are so many starving people in the world. In the developed countries that is not a problem, but in the developing ones where we have a large number of people living below the poverty this may lead to a crisis.

35. Is burning biofuel more environmentally friendly than burning oil?
Fact that producing biofuel is not a "green process“
requires tractors and fertilisers and land
With the increase in biofuel production, more forests will be chopped down to make room for biofuel, ↑ CO2
Better alternative suggested by scientists..
steer away from biofuel and focus on reforestation and maximising the efficiency of fossil fuels instead

36. Comparison of Bioethanol and Biodiesel
Process
Dry-mill method: yeast, sugars and starch are fermented. From starch, it is fermented into sugar, afterwards it is fermented again into alcohol.
Transesterification: methyl esters and glycerin which are not good for engines, are left behind.
Environmental Benefit
Both reduce greenhouse gas emissions as biofuels are primarily derived from crops which absorb carbon dioxide.
Compatibility
ethanol has to be blended with fossil fuel like gasoline, hence only compatible with selected gasoline powered automobiles.
Able to run in any diesel generated engines
Costs
Cheaper
More expensive
Gallons per acre
420 gallons of ethanol can be generated per acre
60 gallons of biodiesel per acre soybeans
cost of soybean oil would significantly increase if biodiesel production is increased as well.
Energy
provides 93% more net energy per gallon
produces only 25% more net energy.
Greenhouse-gas Emissions (GHG)
12% less greenhouse gas emission than the production and combustion of regular diesel
41% less compared to conventional gasoline.

37. Social impacts Created jobs for locals (mainly in rural areas)
Brazilian sugarcane industry has a particularly poor record in respecting worker’s rights
Expansion in sugar cane cultivation may increase food prices. This would leave the poor with a harder survival.
Although the ethanol industry has greatly increased the wealth of the sugar and alcohol sector’s industries, the poor have to be the one handling the negative impacts.

38. Future development
For bioethanol to become more sustainable to replace petrol, production process has to be more efficient
Reducing cost of conversion
Increasing yields
Increase the diversity of crop used
As microbes are use to convert glucose into sugar which is ferment in bioethanol
Microbiology and biotechnology will be helpful in the genetic engineering