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Bio-fuels and hybrids
Prof. Wai ChengSloan Automotive Lab, MIT
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The backdrop
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Transportation and Mobility
Transportation/mobility is a vital tomodern economy
Transport of People Transport of goods and produce
People get accustomed to the ability totravel
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Transportation 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 Watts
Liquid hydrocarbons !
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What is in a barrel of oil ?(42 gallon oil ~46 gallon products)
Source: California Energy Commission, Fuels Office
Asphalt and Road OilLiquefied Refinery Gas
Residual Fuel OilMarketable CokeStill GasJet Fuel
Distillate Fuel OilFinished Motor Gasoline
LubricantsOther Refined Products
0.90%1.50%1.90%2.80%
3.30%5.00%5.40%
12.60%
15.30%51.40%
Typical US output
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US Use of Petroleum by sector
1970 1980 1990 2000 20100
5
10
15
20
25
M i l l i o n s o
f B a r r e
l s / d a y
Year
Transportation
Industrial
ResidentialCommercialElectric utilities
Source: US Dept. of Energy
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Oil Supply (annual average up to 2007)
Source: EIA
0
10
20
30
40
50
60
70
80
90
100
1960 1970 1980 1990 2000 2010
Year
M i l l i o n
B a r r e
l s / d a y
US
OPEC
Others
Hubbert peak
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The world Hubbert peak
Source: http://www.fossil.energy.gov/programs/reserves/npr/publications/npr_strategic_significancev1.pdf
(excluding OPEC & Russian production) 2003
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Petroleum price
0.00
20.00
40.00
60.00
80.00
100.00
120.00
1860 1880 1900 1920 1940 1960 1980 2000
Yom Kippur War Arab Oil Embargo
Iranian Revolution
Iran/Iraq War
Constant 2004$
$ of the day
Oil from North Sea, Alaska
Gulf War
Decrease in demand, increase innon-OPEC supply
Saudi increaseproduction
2008 av. valueup to June;
6/6/08@$118/Barrel
$ / B a r r e
l
Sources:Data from EIA; event labels f rom WTRG Economics
9/11
Demand of emergingmarket;limitedrefinery
capacity
Iraq war
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CO 2 emissions from fossil fuel
1750 1800 1850 1900 1950 20000
1000
2000
3000
4000
5000
6000
70008000
1750 1800 1850 1900 1950 20001
10
102
10 3
104
Year Year
Million metric tons of Carbon/year
Total
Liquid fuel
Total
Liquid fuel
Source: EIA
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The 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 content
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What is bio-fuel?
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Dominant biofuels
Sugar based(corn, sugarcane, )
Cellulosic based(switchgrass, wood, )
Ethanol
Usage
E10, E20, E85,
Crop based(rapeseed, soybean, )
Wasted oil/ animal fat
Algae
Bio-diesel B10, B20, .
Compatible with current enginetechnology and fuel infra structure
(BTL fuel not included in this discussion)
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Example: Ethanol production from corn
Corn
Starch
Sugar
Ethanol + CO2
Ethanol fuel
By-products
Fermentation
Purification(removal of water, )
Resources:Energy
MaterialsLabor
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Example: bio-diesel production
Soy,rapeseed,
Oil (tri-glyceride)
Transesterification using alcohol(methanol) with alkaline catalyst
Mechanical or solvent (hexane)extraction + water removal
Esters and glycerol
Bio-diesel (esters)
Purification
(removal of glycerol,alkaline, fatty acid, )
CH2 -OOC-R 1
CH2 -OOC-R 3
CH-OOC-R 2 +3ROH |
|
R-OOC-R 1
R-OOC-R 3
R-OOC-R 2
Tri-glyceride Esters
+(CH2OH) 2 -CHOH
Glycerol
Resources:Energy
MaterialsLabor
(typically 8-22 C to 2 O)
Alkal ineCatalyst
(KOH)
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Combustion characteristics of bio-fuel
Bio-ester data from Graboski and McCormick , Prog. Energy Comb. Sc., Vol. 24, 1998
Cetanenumber
s.g. LHV(MJ /kg)
LHV(MJ/L)
B10 LHV(MJ /L)
B20 LHV(MJ /L)
LHV B10/Diesel
(by vol.)
LHV B20/Diesel (by
vol.)
Diesel 45-55 0.820 43.22 35.44Soybean oil methylester 50.9 0.885 37.01 32.76 35.17 34.91 0.992 0.985Rapeseed oil methylester 52.9 0.882 37.30 32.90 35.19 34.93 0.993 0.986Sunflower oil methylester 49 0.880 38.53 33.91 35.29 35.14 0.996 0.991Frying oil ethylester 61 0.872 37.19 32.41 35.14 34.84 0.991 0.983
Octanenumber
s.g. LHV(MJ /kg)
LHV(MJ/L)
E10 LHV(MJ /L)
E85 LHV(MJ /L)
LHV E10/Gasoline(by vol.)
LHV E85/Gasoline(by vol.)
Gasoline 95 0.780 44.00 34.32Ethanol 107 0.785 26.90 21.12 33.00 23.10 0.962 0.673
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Stoichiometric requirement for different fuels
1 1.5 2 2.5 3 3.5 42
4
6
8
10
12
14
16
18
Fuel H to C ratio
( A / F ) s t
o i c i o m e
t r i c
Gasolineand diesel
Gasoline with 11% MTBE
Ethanol
Methanol
O/C = 0
O/C = 0.5
O/C = 1
Gasol ine with 10% Ethanol
E85
O/C ratios of bio-dieselesters ~ 0.12B100
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Relative CO2 production from burning different fuel molecules
C. Amann, SAE Paper 9092099
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Effects of Oxygenates on PM emission
AVL Publication (by Wofgang Cartellieri in JSME 1998 Conference in Toykyo)
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Bio-fuel combustion properties
Bio-diesels and ethanol are fundamentally clean andattractive fuels to be used in engines
The use of these fuels as supplements to petroleumbase fuel are compatible with current engineconfiguration and fuel infra-structure
Practical issues can be adequately handled byengineering Fuel quality
Engine calibration Materials compatibility, viscosity,
Burning the fuel is the least of the problem !!!
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Status of bio-fuel production
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World liquid fuel production (2005)
Source: http://www.wilsoncenter.org/topics/pubs/Brazil_SR_e3.pdf
MT = Million tonsBGJ = Billions of giga (10 18)Joules
HYDROCARBONS RENEWABLES
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Liquid fuel supply projection
Source: ExxonMobil JSAE meeting, Kyoto, July 23-26, 2007
1980 1990 2000 2010 2020 2030
120
100
80
60
40
20
0 M i l l i o n s o
f b a r r e
l s p e r
d a y o
i l e
q u i v a
l e n
t
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US bio-fuel capacity
Yield dependent on location and weather
Crop based bio-fuels do not have enoughcapacity to meet the liquid fuel demand !!!
US biofuelsUS harvested crop land (US agriculture census 2002), hectareUS all distillate use (diesel+jet+power gen etc.) EIA2007; L/yrUS gasoline use, EIA 2007; L/yr
1.23E+083.34E+115.40E+11
gal/acre L/hectare
Limit of production
(gal)
Limit of production
(L)
Energyratio of limit todemand
bio-dieselpalm oil 5.08E+02 4,756 1.54E+11 5.85E+11 1.63coconut 2.30E+02 2,153 6.99E+10 2.65E+11 0.74
rapeseed 1.02E+02 955 3.10E+10 1.17E+11 0.33soy 6.00E+01 562 1.82E+10 6.91E+10 0.19peanut 9.00E+01 843 2.73E+10 1.04E+11 0.29sunflower 8.20E+01 768 2.49E+10 9.44E+10 0.27
jatropia (SE Asia) 2.00E+02 1,872 6.08E+10 2.30E+11 0.64algae (?) 1.80E+03 16,850 5.47E+11 2.07E+12 5.78
ethanolcorn 3.44E+02 3,217 1.04E+11 3.96E+11 0.71sugar cane (Brazil) 8.00E+02 7,489 2.43E+11 9.21E+11 1.71
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Algae: micro-seaweedsIssues Production
Need high lipidcontentspecies
Need fastgrowth species
Growth indenseenvironment
Harvest techniques Oil extraction
Courtesy of Prof . Bob Dibble, UC Berkeley
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Current largest algae plant(production of algae for salmon feeding)
Hawaii
Courtesy of Prof . Bob Dibble, UC Berkeley
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Sustainability
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Ethanol from corn Several studies of the overall energy budget
P = energy used in production feedstock production/ transport + processing
E = Energy of the ethanol output Return (%) = (E P) / E
Studies Pimentel and Patzek (2003, 2005): negative return
Return = - 29% USDA (Shapouri et al 2002, 2004): positive return
Return* = +5.6%
Return* = +40% if by products (Corn gluten meal, etc.)are accounted for
Energy balanceExample: Corn ethanol in US
* For comparison purpose, these figures were converted from the
values of (E-P)/P of +5.9% and +67% in the original publication
Verdict:Substantial
environmentaland economic
cost; return notclear
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Other bio-fuels Pimentel and Patzek also estimated energy budget for other bio-
fuels. Returns:
Ethanol from switchgrass = -50% Ethanol from wood biomass = -57% Bio-diesel from soybean = -27% Bio-diesel from sunflower = -118%
Other more positive estimates: Bio-diesel from rapeseed = +32% (EU) Bio-diesel production = +324% (US National Bio-diesel Board)
Outlook: NOT CLEAR New technology needed to change the picture
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Technical difficulties of producing liquid fuel from plants
Glucose fermentation produces significant CO2 out and energy lossC6H12 O6 2C 2H5OH + 2CO 2 + 219.2 KJ
-67.8 KJ -117.3 KJ - 393.5 KJ Cellulose much more difficult to break down than sugar
Hf per mol
of carbonatom
Source: Wikipedia
Glucose
Cellulose
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Effect of government policy on bio-fuel
Current US demand for ethanol is driven bygovernment regulations and incentives Ethanol flex-fuel vehicles produced because of the 74%
credit towards CAFE requirement (E85 vehicle equivalent mph = mpg x 1.74)
Gasoline oxygenate mandate , and phase out of MTBE Energy bill (Aug. 05) mandated a threshold of 7.5 billion
gallons (180 million barrels) production by 2012 Tax subsidy
blenders tax credit $0.51/gallon alcohol $0.051/gallon fuel tax exemption for gasohol
minimum 10 vol % alcohol
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Economic impact of crop-based bio-fuelExample: Corn ethanol in US (~20% of total corn production in 2007)
020406080
100120140160180
1992 1994 1996 1998 2000 2002 2004 2006 2008
Annual fuel ethanol production
M i l l i o n s
o f b a r r e
l s
U.S. All Grades Conventional RetailGasoline Prices (Cents per Gallon) )
0
50
100
150200
250
300
350
400
C e n t s
p e r g a
l
J a n
9 6
J a n
9 7
J a n
9 8
J a n
9 9
J a n
0 0
J a n
0 1
J a n
0 2
J a n
0 3
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0 4
J a n
0 5
J a n
0 6
J a n
0 7
J a n
0 8
J a n
9 5
22.22.42.62.8
3
3.23.43.63.8
4
1 9 9 5
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1 9 9 9
2 0 0 0
2 0 0 1
2 0 0 2
2 0 0 3
2 0 0 4
2 0 0 5
2 0 0 6
2 0 0 7
2 0 0 8
$ p e r g a
l l o n
Fresh whole milk retail price (up to May, 08)
Annual average or averagedup to current month
Spot price 5/12/08:$ 2.50/gal
May 08 spot price: $2.50/galRetail price: $3.80/gal
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Carbon intensity(net mass of CO2 produced per unit fuel energy)
Source: http://en.wikipedia.org/wiki/Biodiesel
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Carbon intensity
Source: http://en.wikipedia.org/wiki/Biodiesel
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Other environmental impact
Water resources
Fertilizer Soil Bio-diversity
Plant waste treatment
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Closure
Bio-diesel and alcohols are excellent fuels fortransportation use Good combustion characteristics Compatible with current engine technology
Sustainability Bio-fuels from crops are not likely to make any
significant impact on the global liquid fuel supplypicture
Land capacity
Effect on food price Further development on other feed stocks needed
Algae for bio-diesel production Cellulosic alcohol
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Closure (continue)
Sustainability issues
Energy budget Water use CO 2 intensity especially with land use
replacement Bio-diversity Other issues
Bio-fuel plant waste treatment Resources requirement
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Hybrid vehicles
Configuration:
IC Engine + Generator + Battery + Electric Motor
Concept
Eliminates external charging As load leveler
Improved overall efficiency
Regeneration ability Plug-in hybrids: use external electricity supply
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Hybrid Vehicles
Examples: Parallel hybrid: Honda InsightSeries hybrid: GM E-Flex SystemPower spli t hybrid: Toyota Prius
ENGINE GENERATOR
MOTORDRIVETRAIN
Power splitHybrid
External charging for plug-ins Regeneration
Battery/ ultracapacitor
ENGINE GENERATOR
MOTOR DRIVETRAIN
Series Hybrid
External charging for plug-ins
Battery/ ultracapacitor
Regeneration
ENGINEMOTOR
DRIVETRAIN
Parallel Hybrid
External charging for plug-ins Regeneration
Battery/ ultracapacitor
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Hybrids and Plug-in hybridsHybrids (HEV) Stored fuel centered
Full hybrid Mild hybrid /power assist
Plug-in hybrids (PHEV) Stored electricity centered
Blended PHEV Urban capable PHEV AER/ E-REV
From SAE 2008-01-0458 (GM)
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Engine/ motor sizing
0
20
40
60
80
100
120
140
160
Hybrid ConversionPHEV
Urban-Capable
PHEV
E-REV P e a
k o n
b o a r
d s u p p
l y / V e
h i c l e d e m a n
d p o w e r
( % )
M o
t o r
E n g
i n e
E n g
i n e
E n g
i n e
E n g
i n e
M o
t o r
M o
t o r M
o t o r
From SAE 2008-01-0456(Toyota)
From SAE 2008-01-0458 (GM)The optimal componentsizing and power distribution strategydepend on the requiredperformance, range,and drive cycle
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The reduced load/ speed dynamic range required from the engine offersdesign opportunities
From SAE 2000-01-2216 (Honda)
Honda Insight 1.0 L engine
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HEV TECHNOLOGY
Toyota Prius Engine: 1.5 L, Variable Valve Timing, Atkinson/Miller
Cycle (13.5 expansion ratio), Continuously Variable Transmission
57 KW at 5000 rpm Motor - 50 KW Max system output 82 KW Battery - Nickel-Metal Hydride, 288V; 21 KW Fuel efficiency:
66 mpg (J apanese cycle) 43 mpg (EPA city driving cycle) 41 mpg (EPA highway driving cycle)
Efficiency improvement (in J apanese cycle) attributed to: 50% load distribution; 25% regeneration; 25% stop and go
Cost: ~$20K
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Efficiency improvement:Toyota Hybrid System (THS)
SAE 2000-01-2930(Toyota)
A: Increase by changing operating area
B: Increase by improvement of engine
Efficiency improvement (in J apanese 10-15 mode cycle) attributed to:50% load distribution; 25% regeneration; 25% stop and go
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Operating map in LA4 driving cycle
0 1000 2500 3000 3500500 1500 2000Speed (rpm)
0
2
6
4
8
B M E P ( b a r )
B M E P ( b a r )
0 500 1000 1500 2000 2500 3000 3500
0
2
8
6
4
Toyota THS II Data from SAE 2004-01-0164Typical passenger car engine
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Cost factor
If $ is price premium for hybrid vehicleP is price of gasoline (per gallon) is fractional improvement in mpg
Then mileage (M) to be driven to break even is
=xPmpgx$M
(assume that interest rate is zero)
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Cost Factor
Example:Honda Civic and Civic-Hybrid
Price premium ( $, MY08 listed) = $7155 ($22600-15445)mpg (city and highway av.) = 29 mpg (42 for hybrid)hybrid improvement in mpg(%) = 45%
At gasoline price of $4.00 per gallon, mileage (M) drivento break even is
miles115,00045%x4$
29x7155$M ==
(excluding interest cost)
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Barrier to Hybrid Vehicles
Cost factor
difficult to justify especially for the small,already fuel efficient vehicles
Battery replacement (not included in the previousbreakeven analysis) California ZEV mandate, battery packs
must be warranted for 15 years or 150,000
miles : a technical challenge
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Hybrid Vehicle Outlook
Hybrid configuration will capture a fraction of thepassenger market, especially when there is significantfuel price increase
Competition Customers downsize their cars
Small diesel vehicles Plug-in hybrids?
Weight penalty (battery + motor + engine)
No substantial advantage for overall CO 2 emissions Limited battery life
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4
S a l e s
( t h o u s a n
d s )
% o f n e w
l i g h t d u t y v e
h i c l e s a l e
Sales figure for hybrid vehicles