Transcript Slide 1
Bioethanol
Bioethanol is produced from plants (biomass) that harness the power of the sun to convert water and CO
2
to sugars (photosynthesis). Biomass like corn are finely ground and separated into their component sugars CO 2 is reabsorb ed by the biomass when growing it Combustion releases CO 2 Prof. R. Shanthini Jan 28, 2012 Ethanol can be used as a fuel The sugars are distilled to make ethanol.
Bioethanol
Bioethanol is produced from plants (biomass) that harness the power of the sun to convert water and CO
2
to sugars (photosynthesis). Prof. R. Shanthini Jan 28, 2012
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 C x (H 2 O) n . Prof. R. Shanthini Jan 28, 2012 http://oregonstate.edu/instruct/dce/ans312/one/carbs_story.htm
Biomass
What is it made up of?
Monosaccharide
(known as simple sugars) is the simplest form of a carbohydrate.
They have the general formula (CH 2 O) n where n = 3 to 7 .
Examples: glucose, fructose and galactose (all are n = 6).
(CH 2 O) 6 or C 6 H 12 O 6 Prof. R. Shanthini Jan 28, 2012 http://oregonstate.edu/instruct/dce/ans312/one/carbs_story.htm
Biomass
What is it made up of?
Prof. R. Shanthini Jan 28, 2012 http://www.tutorvista.com/content/biology/biology-iii/cellular-micromolecules/monosaccharides-and-oligosaccharides.php
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. C 6 H 12 O 6 + C 6 H 12 O 6 C 12 H 22 O 11 + H 2 O Prof. R. Shanthini Jan 28, 2012 http://www.tutorvista.com/content/biology/biology-iii/cellular-micromolecules/monosaccharides-and-oligosaccharides.php
Biomass
What is it made up of?
Prof. R. Shanthini Jan 28, 2012 http://www.tutorvista.com/content/biology/biology-iii/cellular-micromolecules/monosaccharides-and-oligosaccharides.php
Biomass
What is it made up of?
Polysaccharides
monosaccharides. are composed of three or more - 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 http://oregonstate.edu/instruct/dce/ans312/one/carbs_story.htm
Biomass
alpha-glucose
What is it made up of?
beta-glucose Prof. R. Shanthini Jan 28, 2012 http://www.caister.com/supplementary/acanthamoeba/b7.html
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 http://oregonstate.edu/instruct/dce/ans312/one/carbs_story.htm
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 (C 6 H 10 O 5 ) 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
Biomass
What is it made up of?
- Other carbohydrates include
pectins
and
hemicellulose
. -
Pectins
and by
microbes
.
hemicellulose
are only digested and utilized Prof. R. Shanthini Jan 28, 2012 http://www.bio.miami.edu/dana/226/226F09_3.html
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 . Prof. R. Shanthini Jan 28, 2012 Xylose
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 http://oregonstate.edu/instruct/dce/ans312/one/carbs_story.htm
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
Bioethanol
It is simply ethanol
Ethanol formation from glucose:
C 6 H 12 O 6 yeast 2 C 2 H 5 OH + 2 CO 2 + heat glucose ethanol carbon dioxide 180 g 92 g 88 g 26.4 kcal 1 kg 511 g 489 g 147 kcal Prof. R. Shanthini Jan 28, 2012
Bioethanol
Ethanol combustion:
It is simply ethanol C 2 H 5 OH + 3 O 2 ethanol 2 CO 2 + 3 H 2 O + heat
Heat released is 1020 kJ/mol
Prof. R. Shanthini Jan 28, 2012
Bioethanol
oxygen in the ethanol molecule helps in complete combustion, which means less emissions Prof. R. Shanthini Jan 28, 2012
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
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
Bioethanol
Prof. R. Shanthini Jan 28, 2012 Source: http://www.distill.com/World-Fuel-Ethanol-A&O-2004.html
Bioethanol
Bioethanol from simple sugars:
Sugar cane and sugar beets store the energy as simple sugars, glucose (C
6
H
12
O
6
)
yeast 2 C
2
H
5
OH + 2 CO
2
glucose molecule Prof. R. Shanthini Jan 28, 2012 this simple-looking reaction is a bioreaction and thus very complex impure cultures of yeast produce glycerine and various organic acids
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
Bioethanol
sugar cane
Bioethanol from simple sugars:
sugar cane crushed and soluble sugar washed out sugar cane residue (bagasse) yeast / bacteria soluble sugar for fermentation CO
2
5 - 12% ethanol distilled to concentrate to 80 – 95% ethanol can’t be used as petrol additive but as petrol replacement Prof. R. Shanthini Jan 28, 2012 dehydrate to 100% ethanol can be used as petrol additive Dehydration in an expensive process
Bioethanol
Bioethanol from starch:
Corn, wheat and cassava store the energy as more complex sugars, called starch.
alpha-amylase enzyme }
starch (glucose polymer) dextrins
Amyloglucosidase enzyme Prof. R. Shanthini Jan 28, 2012
glucose monomer
Bioethanol
corn flour + water + alpha-amylase enzyme Saccharification with glucosidase enzyme (at 55 - 65 deg C, pH = 4 - 4.5) Fermentation (40 – 50 hrs)
Bioethanol from starch:
Liquification (at 90 – 95 deg C; pH = 4 - 4.5; 400 rpm) Cooling (32 deg C) Distillation
80-95% ethanol
Prof. R. Shanthini Jan 28, 2012 Dehydration
100% ethanol
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
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
Bioethanol
Bioethanol from biomass (other than sugars and starches):
Rice straw Paddy husks Saw dust Grasses Bagasse Prof. R. Shanthini Jan 28, 2012
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
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.
Prof. R. Shanthini Jan 28, 2012 Xylose
Prof. R. Shanthini Jan 28, 2012
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
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
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
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
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
Bioethanol
Water Requirements for Energy Production by different process Process
petroleum extraction oil refining oil shale surface retort NGCC power plant, closed loop cooling coal IGCC nuclear power plant, closed loop cooling geothermal power plant, closed loop tower
Litre/MWh
10 - 40 80 - 150 170 - 681 230 - 30,300 ≈ 900 ≈ 950 1900 - 4200 NGCC: Natural gas combined cycle IGCC: Integrated gasification combined-cycle Jan 28, 2012 Energy Demands on Water Resources; Report to Congress on the Energy: Washington, DC, 2006; p 80.
Bioethanol
Water Requirements for Energy Production by different process Process
Enhanced oil recovery
Litre/MWh
≈ 7600 NGCC, open loop cooling 28,400 75,700 nuclear power plant, open loop cooling 94,600 - 227,100 corn ethanol irrigation soybean biodiesel irrigation 2,270,000 - 8,670,000 13,900,000 - 27,900,000 NGCC: Natural gas combined cycle IGCC: Integrated gasification combined-cycle Jan 28, 2012 Energy Demands on Water Resources; Report to Congress on the Energy: Washington, DC, 2006; p 80.
Bioethanol
Water Requirements for Energy Production by different process Process Litre/MWh
petroleum extraction + oil refining 90 - 190 nuclear power plant, closed loop cooling ≈ 950 nuclear power plant, open loop cooling 94,600 - 227,100 corn ethanol irrigation 2,270,000 - 8,670,000 soybean biodiesel irrigation 13,900,000 - 27,900,000 Jan 28, 2012 In summary Energy Demands on Water Resources; Report to Congress on the Energy: Washington, DC, 2006; p 80.