Study Guide - University Of Washington

Study Guide Biofuel vs Petroleum-based fuelExam questions will relate the lecturesto each other– Advantages and disadvantages of thedifferent fuels (methanol, ethanol,bioethanol, and biodiesel) and comparedto petroleum– How are they similar and different fromeach other? Make a table to compareEXAM # 2 IS ON TUESDAY NOVEMBER 30TH: Endophyte-AssistedPhytoremediation plus the three bioenergy lectures so far

Bioenergy Lectures Th Nov 16- OverviewTu Nov 18- BiodieselTh Nov 23- Bioethanol and methanolTu Nov 25- HolidayNov 30- EXAM #2 (Phyto with endophytes; first 3bioenergy lectures)Dec 2-Ways to improve the efficiency of biofuelproductionDec 7- (cont.)Dec 9- Environmental applications of trees; paperassignment givenDec 13- Final exam (75 pts) on last 3 lectures (inclass for both ESRM and CFR); Paper (50 pts) is due

Bioethanol(Many of the following slides are fromProf. Renata Bura)

Overview What is bioconversion?Why bioconversion?Biomass compositionBioconversion to ethanol process––– PretreatmentHydrolysisFermentationPros and cons of bioethanolComparison to other biofuels

What is bioconversion? General: a process which uses biologicalagents (microorganisms or protein) totransform a feedstock into desirableproducts.BioethanolA chemical/biochemical process by whichlignocellulosic materials are converted toethanol and other co-products.

ermentationDistillation

Ethanol (CH3CH2OH) Ethyl alcohol, grain alcohol– Clear, colorless liquid Ethanol made from cellulosic biomass instead ofstarch crops-bioethanolAdvantages of bioethanol–––––Domestic renewable fuel sourcesReduces reliance on foreign oilCleaner fuel sourcesEasily produced and storedIncreases fuel octane number for little cost

Energy contentGasolineEthanolBiodiesel100%67%86%

Henry Ford“We can get fuel from apples, weeds,sawdust, almost anything .And it remains for someone to find how thisfuel can be produced commerciallybetter fuel at a better price than we nowknow.”Henry Ford

Why bioconversion? Energy– An alternative source of energy for thetransportation sector produced locally Air pollution– Reduction in greenhouse gas emission Waste elimination– Elimination of problems with fieldburning/incineration, stockpiling, etc. Socio/economical benefits– Creation of new jobs, rural development

Possible feedstocks Agricultural residues (corn stover, cornfibre, wheat straw, rice straw)Wood residues:– Hardwood (poplar, willow)– Softwood (Douglas-fir, lodgepole pine) Paper wasteMunicipal solids waste

Overview What is bioconversion?Why bioconversion?Biomass compositionBioconversion to ethanol process––– PretreatmentHydrolysisFermentationPros and cons of bioethanolComparison to other biofuels

Biomass composition

Cellulose

Hemicellulose

Lignin

Lignin A majorbarrier toaccessing thecelluloseProvidesstrength andrigidity

Overview What is bioconversion?Why bioconversion?Biomass compositionBioconversion to ethanol process––– PretreatmentHydrolysisFermentationPros and cons of bioethanolComparison to other biofuels

Bioconversion of biomass toethanol (pretreatment)LiquidPretreatment ySolid phaseCelluloseHydrolysisFermentationSugarsEthanol

Pretreatment Helps in separation of main biomasscomponents (cellulose, hemicellulose andlignin)Increase available surface areaReduce particle sizeIdeally pretreatment:– Solubilizes hemicellulose– Increases enzymatic hydrolysibility ofcellulose

Pretreatment –”disruption” Possible methods:– Mechanical (milling)– Chemical (acid and base)– Biological– Combination

Steam explosion Treatment of biomass with high-pressuresteam for a short period of time followed bysudden decompressionAcid (H2SO4, SO2) impregnation of biomassincreases SE efficiencyTypical conditions:– Temperature: 170-250oC, 338-482 F– Time: 10sec-10min

Steam gunFill valveReceivingKarinvesselReceivingvesselSteam valveBlow valvePretreated corn stover

Overview What is bioconversion?Why bioconversion?Biomass compositionBioconversion to ethanol process––– PretreatmentHydrolysisFermentationPros and cons of bioethanolComparison to other biofuels

Bioconversion of biomass toethanol (hydrolysis)LiquidPretreatment ySolid phaseCelluloseHydrolysisFermentationSugarsEthanol

CelluloseThe goal of the hydrolysis step is to breakthe cellulose into simple sugars prior tofermentation

Must be able to break cellulose toget the energy Cows, deer, sheepRumen is afermentation vatMicrobes breakdown the celluloseusing the enzyme,cellulase

Fungi can break down cellulose too Cellulases areenzymes thatbreak downcelluloseWhite rot fungi:good source ofenzymes

What are cellulases? Enzymes made by many strains of bacteriaand fungiCatalyzes the depolymerization of cellulosechains– (details in Renata Bura’s class)

Overview What is bioconversion?Why bioconversion?Biomass compositionBioconversion to ethanol process––– PretreatmentHydrolysisFermentationPros and cons of bioethanolComparison to other biofuels

Bioconversion of biomass toethanol (fermentation)LiquidPretreatment ySolid phaseCelluloseHydrolysisFermentationSugarsEthanol

Fermentation Defined as:Cellular metabolism under anaerobic conditions(absence of oxygen) for the production of energyand metabolic intermediates Many organisms can “ferment”Not all produce ethanol as an end-product

Strain selection Traditionally been a YeastYeast:––– Single cell microorganismFungiFacultative anaerobeMost common industrial fermenter isSaccharomyces cerevisiae (baker’s or brewer’syeast)Why?

Why S. cerevisiae? Has been selected over thousands of yearsHigh ethanol yield and productivityRelatively simple to culture

Fermentation(Glycolysis first)

FERMENTATIONIf electron acceptor(such as oxygen)is presentCellular S CYCLEELECTRON TRANSPORT ANDOXIDATIVE PHOSPHORYLATIONPyruvateFERMENTATIONIf electron acceptor(such as oxygen)is NOT present

Fermentation Regenerates NAD Fermentation pathways allow cells to regenerate NAD for glycolysis.Fermentationby-productIntermediate acceptselectrons from NADHGENERAL PATHWAY

Alcohol fermentation occurs in yeast.2 Pyruvate2 Ethanol2 Acetylaldehyde

FermentationConversion factor 0.511g/L of glucose: 0.51g/L ethanol (maximum)

Overview What is bioconversion?Why bioconversion?Biomass compositionBioconversion to ethanol process––– PretreatmentHydrolysisFermentationPros and cons of bioethanolComparison to other biofuels

Challenges (Cons) Feedstock diversityEconomical feasibility of the process– Cost of biomass– Cost of enzymes– Ethanol as a final product very cheap

Pros (again) Energy– An alternative source of energy for thetransportation sector produced locally Air pollution– Reduction in greenhouse gas emission Waste elimination– Elimination of problems with fieldburning/incineration, stockpiling, etc. Socio/economical benefits– Creation of new jobs, rural development

Sugar cane & sugar canebagasseSugarcanebagasseProcessingEthanol

Corn plant

uctioncost ( )EnergybalanceGHEreduction(%)Corn grain ethanol4.861.091.322Cane ellulosic ethanolBiodiesel

Part 2. MethanolCasioToshiba

Biomass to Liquid FuelCrude SyngasGasifierGasifierScrubberClean SyngasMethanolReactorWoodBiomass(Syngas CO2 CO H2 )Bio-Methanol(Wood Alcohol)

How is biomethanol made? All the woody biomass is usedNOT FROM FERMENTATIONWood chips Æ gasifier at high tempÆscrubbers Æ biomethanolWood to bioethanol yields 99-142 galWood to biomethanol yields 165-186gal BECAUSE IT USES ALL THEBIOMASS, NOT JUST THE SUGAR

2.Principle of methanol synthesisby the gasification methodCO 2H2CarbonHydrates:Mixture ofGases:(CH2O)n Oxygen water1000 CBiomethanolHydrogen, carbonmonoxide, carbondioxide, waterPressure40-80 atmSlide adapted from H. NakagawaCH3OH

Typical test questions How is bioethanol and biomethanoldifferent in terms of how they aremade?How is biodiesel different from bothbioethanol and biomethanol in termsof the plant material used?

Some conversion efficiencies to alcoholsMaterialSugar canewww.itdg.org/docs/technical information service/sugar production from cane.pdf,gar production from cane.pdf, K Vogt estimateCorner stoverKheshgi et al. ww.cfr.washington.edu/research.Forest Energy/www.cfr.washington.edu/research.Forest Energy/,Kheshgi et al. 2000, K Vogt estimateNOTE: Ethanolcannot be madefrom lignin, a majorcomponent ofwaste biomassEthanolMethanol(gallons / 1 Mg biomass)(gallons/ 1 Mg biomass)24 – 36 gallons(6 - 9%)79 – 119gallons99 – 142gallonsStarch orCellulosebeingconvertedChemistrydetermines howmuch liquid byproductproduced165 – 186gallonsCelluloseand ligninbeingconverted

Then why the focus on bioethanolinstead of biomethanol? Plants contain a lot of nitrogen (notjust “carbon hydrates”)Gasification of nitrogen in thepresence of oxygen makes toxic NOgasesToxic byproductsLower energySmaller market (but maybe changing)

SFR biofuels research agendaVision: Cost effective cellulosic transportation fuels Use mixed biomass sources With good process yields Profitable at moderate economies ofscale Co-produce fuels and high valueproducts Commodity Chemicals Polymers Pulp Fibers

Review Ethanol from fermentation of starch fromgrain or sucrose from sugarcaneBioethanol from fermentation of anycellulosic biomass- can be producedsustainably; can be mixed with gasolineBiodiesel from plant oils- high energy fuel;not compatible with most US cars (yes-bus)Biomethanol- lower energy; smaller market;but efficient production; can be used inpower cells

Study Guide Biofuel vs Petroleum-based fuelExam questions will relate the lecturesto each other– Advantages and disadvantages of thedifferent fuels (methanol, ethanol,bioethanol, and biodiesel) and comparedto petroleum– How are they similar and different fromeach other? Make a table to compareEXAM # 2 IS ON TUESDAY NOVEMBER 30TH: Endophyte-AssistedPhytoremediation plus the three bioenergy lectures so far

Comparing Fuels Structure– Diesel: saturated hydrocarbons, C10-C15– Biodiesel:– Ethanol/Bioethanol:– Methanol:Energy content– Diesel: High energy content– Biodiesel:– Ethanol/Bioethanol:– MethanolAir pollution– Diesel: High– Biodiesel:– Ethanol/Bioethanol:– Methanol:

Fuel Comparisons (cont.) What is it?Sources?Microbes needed?How is each different from petroleumor diesel?Benefits of the biofuel?

References www.ento.vt.edu/ w n/cf13.htmwww.eere.energy.gov/biomass/

Bioenergy Lectures Th Nov 16- Overview Tu Nov 18- Biodiesel Th Nov 23- Bioethanol and methanol Tu Nov 25- Holiday Nov 30- EXAM #2 (Phyto with endophytes; first 3 bioenergy lectures) Dec 2-Ways to improve the efficiency of biofuel production Dec 7- (cont.) Dec 9- Environmental applications of trees; paper assignment given Dec 13- Final exam (75 pts) on last 3 lectures (in