bio-fuels and hybrids

7/30/2019 Bio-Fuels and Hybrids

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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

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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

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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) )

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$ 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


Regeneration

ENGINEMOTOR

DRIVETRAIN

Parallel Hybrid

External charging for plug-ins Regeneration



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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

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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

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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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Sales figure for hybrid vehicles

bio-fuels and hybrids

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