Prof. R. Shanthini 09 Feb 2013 Module 07 Renewable Energy (RE) Technologies & Impacts (continued) - Use of RE sources in electricity generation, in transport, and in other energy consumption modes -Ecological impacts of RE sources, and mitigation measures

Prof. R. Shanthini 09 Feb 2013 RE technology options: - Hydroelectric - Hydroelectric - Solar - Solar - Wind - Wind - Geothermal - Marine (Wave and Tidal) Biofuels Biomass Bioethanol - Biofuels (Biomass, Bioethanol and Biodiesel)

Prof. R. Shanthini 09 Feb 2013 Bioethanol Bioethanol is simply ethanol. It is called bioethanol when it is produced from biomass. Fuel made by blending ethanol with petrol assures that the fuel mixture burns more completely. Oxygen in the ethanol molecule helps in complete combustion, which means less emissions.

Prof. R. Shanthini 09 Feb 2013 Ethanol is a high-octane fuel, and is widely used as a blending ingredient in petrol. Bioethanol 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 09 Feb 2013 Bioethanol The most common blend is 10% ethanol and 90% petrol (E10), which is also known as gasohol. Vehicle engines require no modifications to run on E10 and vehicle warranties are unaffected also. Only flexible-fuel vehicles (FFV) can run on up to 85% ethanol and 15% petrol blends (E85).

Prof. R. Shanthini 09 Feb 2013 Source: Bioethanol

Prof. R. Shanthini 09 Feb 2013 Bioethanol C 2 H 5 OH2 CO H 2 O + heat ethanol Heat released is 1020 kJ/mol. CO 2 is also released as when petrol is being burned. So what is the big deal? Ethanol combustion: + 3 O 2

Prof. R. Shanthini 09 Feb 2013 Bioethanol Bioethanol is produced from plants (biomass) that harness the power of the sun to convert water and CO 2 to sugars (photosynthesis). CO 2 is reabsorbed by the biomass when growing it. So it is OK. CO 2 sun light biomass ethanol water

Prof. R. Shanthini 09 Feb 2013 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 09 Feb 2013 Bioethanol - 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. What is biomass made up of?

Prof. R. Shanthini 09 Feb 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 Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb 2013 Bioethanol C 6 H 12 O 6 2 C 2 H 5 OH+ 2 CO 2 + heat Yeast glucose ethanol carbon dioxide 180 g 92 g 88 g 26.4 kcal 1 kg 511 g 489 g 147 kcal Ethanol formation from glucose: Bioethanol from glucose:

Prof. R. Shanthini 09 Feb 2013 Bioethanol Glucose does not exist as glucose in nature. So, go to sugars that are slightly more complex than the simple sugars considered so far.

Prof. R. Shanthini 09 Feb 2013 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 12 H 22 O 11 + C 6 H 12 O 6 + H 2 O Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb 2013 Bioethanol from sucrose: Sugar cane and sugar beets store the energy as sucrose (C 12 H 22 O 11 ) 2 C 2 H 5 OH + 2 CO 2 zymase Impure cultures of yeast produce glycerine and various organic acids Invertase and zymase are enzymes derived mainly from yeast. Bioethanol C 6 H 12 O 6 2 C 6 H 12 O 6 invertase C 12 H 22 O 11 + H 2 O

Prof. R. Shanthini 09 Feb 2013 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 Bioethanol

Prof. R. Shanthini 09 Feb 2013 sugar cane crushed and soluble sugar washed out sugar cane residue (bagasse) can’t be used as petrol additive but as petrol replacement can be used as petrol additive CO 2 Bioethanol distilled to concentrate to 80 – 95% ethanol % ethanol sugar cane yeast / bacteria soluble sugar for fermentation dehydrate to 100% ethanol Dehydration in an expensive process Bioethanol from sucrose:

Prof. R. Shanthini 09 Feb 2013 Bioethanol

Prof. R. Shanthini 09 Feb What about ethanol from corn as it the USA? Bioethanol

Prof. R. Shanthini 09 Feb Corn belong to the family of starch. Starch is a polysaccharide, which is composed of three or more monosaccharides. The two primary polysaccharides are starch and cellulose. Both starch and cellulose are composed of glucose molecules. So it is possible to convert starch (and cellulose) to glucose and then to ethanol. The primary difference between starch and cellulose is the linkage of their units. Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb alpha-glucose beta-glucose Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb 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. Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb 2013 Corn, wheat and cassava store the energy as starch. dextrins alpha-amylase enzyme Amyloglucosidase enzyme glucose monomer } starch (glucose polymer) Bioethanol Bioethanol from starch:

Prof. R. Shanthini 09 Feb 2013 Liquification (at 90 – 95 deg C; pH = ; 400 rpm) Saccharification with glucosidase enzyme (at deg C, pH = ) Cooling (32 deg C) Fermentation (40 – 50 hrs) Dehydration 80-95% ethanol 100% ethanol corn flour + water + alpha-amylase enzyme Bioethanol Bioethanol from starch: Distillation

Prof. R. Shanthini 09 Feb 2013 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. Bioethanol Bioethanol from starch:

Prof. R. Shanthini 09 Feb 2013 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 Bioethanol Bioethanol from starch:

Prof. R. Shanthini 09 Feb 2013 Rice straw Paddy husks Saw dust Grasses Bagasse Bioethanol Bioethanol from biomass (other than sugars and starches): They are rich in cellulose and lignin.

Prof. R. Shanthini 09 Feb Cellulose is the major structural material of biomass - Cellulose is made from several 100s to over 10,000s glucose molecules - Cellulose has the formula (C 6 H 10 O 5 ) n - Cellulose can be hydrolyzed to glucose molecules - The crystalline structure of cellulose makes it resistant to hydrolysis Bioethanol What is it made up of?

Prof. R. Shanthini 09 Feb Other carbohydrates include pectins and hemicellulose. - Pectins and hemicellulose are only digested and utilized by microbes. Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb Hemicellulose comprise almost 1/3 of the carbohydrates in woody plant tissues. - It is made mainly from the five-carbon sugar, xylose. Bioethanol Xylose What is biomass made up of?

Prof. R. Shanthini 09 Feb Hemicellulose is relatively easy to be hydrolyzed 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. Bioethanol Bioethanol from biomass (other than sugars and starches):

Prof. R. Shanthini 09 Feb 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. Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb 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. Bioethanol What is biomass made up of?

Prof. R. Shanthini 09 Feb 2013

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 Source: DOE's 2006 Annual Energy Outlook Bioethanol Bioethanol from cellulose:

Prof. R. Shanthini 09 Feb 2013 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. Source: DOE's 2006 Annual Energy Outlook Bioethanol Bioethanol from cellulose:

Prof. R. Shanthini 09 Feb 2013 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. Bioethanol

Prof. R. Shanthini 09 Feb 2013 Bioethanol will be used in engines that convert heat into work Engines that convert heat into work are very inefficient Bioethanol

Prof. R. Shanthini 09 Feb 2013 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) Bioethanol

Prof. R. Shanthini 09 Feb 2013 Bioethanol Water Requirements for Energy Production by different process 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 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. NGCC: Natural gas combined cycle IGCC: Integrated gasification combined-cycle

Prof. R. Shanthini 09 Feb 2013 Bioethanol Water Requirements for Energy Production by different process 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 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. NGCC: Natural gas combined cycle IGCC: Integrated gasification combined-cycle

Prof. R. Shanthini 09 Feb 2013 Bioethanol Water Requirements for Energy Production by different process 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 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. In summary