MIT OpenCourseWare http://ocw.mit.edu 2.61 Internal Combustion Engines Spring 2008 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.1Bio-fuels and hybridsProf. Wai ChengSloan Automotive Lab, MIT2The backdrop3Transportation and Mobility• Transportation/mobility is a vital to modern economy–Transport of People–Transport of goods and produce• People get accustomed to the ability to travelTransportation needs special kind of energy source• Vehicles need to carry source of energy on board• Hydrocarbons are unparalleled in terms of energy density– For example, look at refueling of gasoline• ~40 Liters in 2 minutes (~0.25 Kg/sec)– Corresponding energy flow= 0.25 Kg/sec x 44 MJ/Kg= 11 Mega Watts4Liquid hydrocarbons !5What is in a barrel of oil ?(42 gallon oil → ~46 gallon products)Source: California Energy Commission, Fuels OfficeLLSJFubricants0.90%Other Refined Products1.50%Asphalt and Road Oil1.90%iquefied Refinery Gas2.80%Residual Fuel Oil3.30%Marketable Coke5.00%till Gas5.40%et Fuel12.60%Distillate Fuel Oil15.30%inished Motor Gasoline51.40%Typical US output6US Use of Petroleum by sector1970 1980 1990 2000 20100510152025Millions of Barrels/dayYearTransportationIndustrialResidentialCommercialElectric utilitiesSource: US Dept. of Energy7Oil Supply (annual average up to 2007)Source: EIA10090Million Barrels/day807060504030201001960 1970 1980 1990 2000 2010YearOthersOPECUSHubbert peak8The world Hubbert peak(excluding OPEC & Russian production)2003Source: http://www.fossil.energy.gov/programs/reserves/npr/publications/npr_strategic_significancev1.pdfImage removed due to copyright restrictions. Please see Fig. 9 in Zittel, Werner, and Jörg Schindler. "Future World Oil Supply." Salzburg, Germany: International Summer School on the Politics and Economics of Renewable Energy, July 2002.9Petroleum price0.0020.0040.0060.0080.00100.00120.001860 1880 1900 1920 1940 1960 1980 2000Yom Kippur WarArab Oil EmbargoIranian RevolutionIran/Iraq WarConstant 2004$$ of the dayOil from North Sea, AlaskaGulf WarDecrease in demand, increase in non-OPEC supplySaudi increase production2008 av. value up to June;6/6/08 @$118/Barrel$/Barrel9/11Demand of emerging market; limited refinery capacityIraq warSources: Data from EIA; event labels from WTRG Economics10CO2emissions from fossil fuel1750 1800 1850 1900 1950 20000100020003000400050006000700080001750 1800 1850 1900 1950 2000110102103104YearYearMillion metric tons of Carbon/yearTotalLiquid fuelTotalLiquid fuelSource: EIA11The drive to bio-fuel• Increasing demand of liquid fuel for transportation– Population– Society affluence• Drive for lower CO2 production• Perceived decline of petroleum reserve• Fuel price• Government Policy– Tax credit– Required bio-fuel content12What is bio-fuel?Dominant biofuelsSugar based(corn, sugarcane, …)UsageEthanol E10, E20, E85, …Cellulosic based(switchgrass, wood, …)Crop based(rapeseed, soybean, …)Wasted oil/ animal fatBio-dieselAlgae13B10, B20, ….Compatible with current engine technology and fuel infra structure(BTL fuel not included in this discussion)14Example: Ethanol production from cornCornStarchSugarEthanol + CO2Ethanol fuelBy-productsFermentationPurification(removal of water, …)Resources:EnergyMaterialsLabor15Example: bio-diesel productionSoy,eseed, …Oil (tri-glyceride)Transesterification using alcohol (methanol) with alkaline catalystMechanical or solvent (hexane) extraction + water removalEsters and glycerolBio-diesel (esters)Purification(removal of glycerol, alkaline, fatty acid, …)CH2-OOC-R1CH2-OOC-R3CH-OOC-R2+3ROH ↔||R-OOC-R1R-OOC-R3R-OOC-R2Tri-glyceride Esters+(CH2OH)2-CHOHGlycerolResources:EnergyMaterialsLabor(typically 8-22 C to 2 O)AlkalineCatalyst(KOH)rap16Combustion characteristics of bio-fuelCetane s.g. LHV LHV B10 LHV B20 LHV LHV B10/ LHV B20/ number(MJ/kg)(MJ/L)(MJ/L) (MJ/L) Diesel Diesel (by (by vol.) vol.)sel45-55 0.820 43.22 35.44ybean oil methylester 50.9 0.885 37.01 32.76 35.17 34.91 0.992 0.985peseed oil methylester 52.9 0.882 37.30 32.90 35.19 34.93 0.993 0.986nflower oil methylester 49 0.880 38.53 33.91 35.29 35.14 0.996 0.991ing oil ethylester 61 0.872 37.19 32.41 35.14 34.84 0.991 0.983Octane s.g. LHV LHV E10 LHV E85 LHV LHV E10/ LHV E85/ number(MJ/kg)(MJ/L)(MJ/L) (MJ/L) Gasoline Gasoline (by vol.) (by vol.)soline95 0.780 44.00 34.32anol107 0.785 26.90 21.12 33.00 23.10 0.962 0.673Bio-ester data from Graboski and McCormick, Prog. Energy Comb. Sc., Vol. 24, 1998DieSoRaSuFryGaEth17Stoichiometric requirement for different fuels1 1.5 2 2.5 3 3.5 424681012141618Fuel H to C ratio(A/F)stoiciometricGasoline and dieselGasoline with 11% MTBEEthanolMethanolO/C = 0O/C = 0.5O/C = 1Gasoline with 10% EthanolE85O/C ratios of bio-diesel esters ~ 0.12B100Relative CO2 production from burning different fuel moleculesC. Amann, SAE Paper 909209918Image removed due to copyright restrictions. Please see Amann, Charles A. “The Passenger Car and The Greenhouse Effect.” SAE Journal of Passenger Cars 99 (October 1990): 902099.Effects of Oxygenates on PM emissionAVL Publication (by Wofgang Cartellieri in JSME 1998 Conference in Toykyo)190 10 20 30 40 50Fuel oxygen content - %020406080100Soot reduction - %100% Methanol100% Dimethyl ether (DME),100% EthanolWater/Diesel emulsion (15 to 20% water)100% Rapeseed methyl ester (RME)Diglyme, methylal added to diesel fuel(6 to 14% wt.){{{Figure by MIT OpenCourseWare.20Bio-fuel combustion properties• Bio-diesels and ethanol are fundamentally clean and attractive fuels to be used in engines• The use of these fuels as supplements to petroleum base fuel are compatible with current engine configuration and fuel infra-structure• Practical issues can be adequately handled by engineering– Fuel quality– Engine calibration– Materials compatibility, viscosity, …Burning the fuel is the least of the problem !!!21Status of bio-fuel production22World liquid fuel production (2005)HYDROCARBONSRENEWABLESImage removed due to copyright restrictions. Please see p. 2 in Budny, Daniel. "The Global Dynamics of Biofuels." Brazil Institute Special Report. Washington, DC: Woodrow Wilson International Center for Scholars, April 2007.23Liquid fuel supply projectionSource: ExxonMobil – JSAE meeting, Kyoto, July 23-26, 20071980 1990 2000 2010 2020 2030120100806040200Millions of barrels per day oil equivalent24US bio-fuel capacityUS biofuelsUS harvested crop land (US agriculture census