Bob McCormickNational Renewable Energy Laboratory

Fuel-Engine Compatibility andPerformance of Biodiesel

Presented atARB/CEC Alternative Diesel Fuel Symposium

August 20, 2003Sacramento, California

303-275-4432robert_mccormick@nrel.gov

Biodiesel Overview

•Methyl esters of fatty acids

O

CH3

oleicacid

O

CH3

linoleicacid

O

CH3

linolenic acid

O

oleicacid

O

oleicacid

O

linoleicacid

O

linoleicacid

O

linolenic acid

O

linolenic acid

O

CH3

oleicacid

O

CH3

oleicacid

O

CH3

linoleicacid

O

CH3

linoleicacid

O

CH3

linolenic acid

O

oleicacid

O

oleicacid

O

linoleicacid

O

linoleicacid

O

linolenic acid

O

linolenic acid

SoyCornCanolaSunflowerMustardCottonseedLardEdible TallowInedible TallowYellow GreaseOther GreasesTrap Grease

•US resource size roughly 2 billionannual gal•~20 million gal estimated in salesfor 2002

•Annual European production ~200million gal (600 million gal/yrcapacity)

Energy Security and Global Warming BenefitsFor Soybean-based biodiesel:

Life Cycle Energy Efficiency = 83% for petroleum diesel = 81% for biodiesel

• Roughly the same amount of energy is required to produce refinedpetroleum diesel and biodiesel

Fossil Energy Ratio = Fuel Energy/Fossil Energy Inputs = 3• Fossil energy used in production is small fraction of fuel energy-truly

renewable, highest ratio of any fuel currently produced

Analysis from NREL/TP-580-24772, May 1998

Biodiesel Strategies & Regulatory Status•Utilization strategy-blending with petroleum diesel

•20% (B20) blends initially pursued as economic compromise•May shift to 5% blends because of OEM concerns•20% blends for EPAct fleets

•Energy security and environmental benefits proportional to total volumeused, not blend level•ASTM standard published in January, 2002•EPA fuel registration requirements met (CCA 211b)

ASTM D6751:

Biodiesel Compared to No. 2 Diesel

←10% lower energy content

←More viscous

←Higher T90

←Higher cetane←Very low sulfur and

aromatics←Higher cloud point

Property Method Typical No. 2 100% Soy Biodiesel LHV, btu/gal D240 131,000 117,000 Density, 15oC D4052 0.85 0.88 Viscosity, cP D445 2.7 4.1 Distillation, oC D86 IBP 174 300 10% 215 328 50% 253 336 90% 312 350 FBP 344 360 Carbon Residue D524/D45

00<0.35 <0.1

Cetane number D613 45 ~50 Sulfur, ppm D5453 300 <1 Total Aromatics D5186 ~30 0 Cloud Point, °C D2500 -15 0

←Lower carbon residue

Biodiesel Blend Properties

• 5% blends nosignificant change

• 20% blends showsmall propertychanges

Property Method* Typical No. 2 B20 B5 LHV, btu/gal D240 131,000 128,000 130,000 Density, 15oC D4052 0.85 0.87 0.85 Viscosity, cP D445 2.7 2.9 2.7 Distillation, oC D86 IBP 174 174 174 10% 215 225 215 50% 253 265 253 90% 312 335 320 FBP 344 346 346 Carbon Residue <0.35 -- -- Cetane number D613 45 46 45 Sulfur, ppm D5453 300 240 285 Total Aromatics D5186 ~30 ~24 ~28 Cloud Point, °C D2500 -15 -10 -15

Blending mitigates property differences

Biodiesel Effect on Lubricity

Weight Percent Biodiesel0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

SLB

OC

LE, g

3000

3500

4000

4500

5000

5500

6000

6500

7000

SoyCanolaTallow-1Tallow-2LardLFFA Yellow GreaseHFFA Yellow Grease

ASTM is currently considering a lubricity standard for diesel fuel•0.5wt% biodiesel can increase SLBOCLE by roughly 1000 g orreduce HFRR 200 micron•Thus low biodiesel blends may reduce engine wear

Data from NREL/SR-510-31460, April 2003

Volume % Soydiesel0 20 40 60 80 100

HFR

R, m

icro

n

100

200

300

400

500

600

Range of proposedlubricity standards

Data from SAE 2002-01-1658

Cold Flow of Biodiesel Blends

Weight Percent Biodiesel0 1 2 3 4 5 6

Col

d Fi

lter P

lugg

ing

Poin

t, o C

-25

-20

-15

-10

-5

SoyCanolaLardTallow-1Tallow-2LFFA Yellow GreaseHFFA Yellow Grease

•Pure biodiesel begins to freeze atinconvenient temperatures-above32oF•Below 20% blend the impact oncold flow is small,•And even smaller below 5%:

•Vegetable oil-derived fuelshave no impact on CP or CFPP•Impact is larger butmanageable for more saturatedanimal fat-derived fuels

•Blending of No. 1 diesel and use ofcold flow additives are effectivestrategies for B20

Data from NREL/SR-510-31460, April 2003

Volume % Biodiesel

0 20 40 60 80 100

Clo

ud P

oint

, o C

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

Biodiesel Emissions

• PM reduction, NOx increase roughlylinear with blend level

• NOx Increase, 2-4% for B20 over a rangeof engines

• Apparently no data for engine meeting1998 (4 g/bhp-h) or 2004 (2.5 g/bhp-h)NOx emission standards

Weight Percent Biodiesel0 20 40 60 80 100

PM, g

/bhp

-h

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

Weight Percent Biodiesel0 20 40 60 80 100

NOx,

g/bh

p-h

4.5

5.0

5.5

Data from SAE 961166, 1991 DDC Series 60 engine

1991 S60 1995 B5.9 1997 N14 1997 S50 1997 3406E

NO

x Em

issi

on, g

/bhp

-h

3.0

3.5

4.0

4.5

5.0

5.5

6.0

No. 2 DieselB20B100

Toxics Emissions

1997 N14 1997 S50 1995 B5.9

C1-

C12

HC

, mg/

bhp-

h

0

10

20

30

40

50

60

70

2D B20 B100

1997 N14 1997 S50 1995 B5.9

Tota

l Ald

ehyd

e, m

g/bh

p-h

0

20

40

60

80

100

120

2D B20 B100

1997 N14 1997 S50 1995 B5.9

Rel

ativ

e O

zone

For

min

g Po

tent

ial

of C

1-C

12 +

Ald

ehyd

e2D B20 B100

1997 N14 1997 S50 1995 B5.9

Sele

cted

PAH

, ng/

bhp-

h

0

2000

4000

6000

8000

10000

12000

14000

16000

2D B20 B100

1997 N14 1997 S50 1995 B5.9

Sele

cted

Nitr

o-PA

H, n

g/bh

p-h

0

100

200

300

400

500

600

2D B20 B100

Generally lower for biodiesel:

NOx Reduction StrategiesInjection timing retard:• Can eliminate NOx increase for pre-1998

engines• Reduces or eliminates PM benefit• Can reduce fuel economy• Requires engine certified on and dedicated

to biodiesel Graboski & McCormick, Progress in Energy and Combustion

Science, 24 125 (1998).

Ongoing research:• Fuel and injection sensors for feedback

control of injection timing Tat & Van Gerpen, Applied Eng. In Agr., 19 125 (2003)

Cetane increasing additives:• Both EHN and DTBP effective for soy B20• NOx reductions significant at 95%

confidence or greater• No change in PM emissions or fuel

economy McCormick, et al., SAE Tech. Pap. No. 2002-01-1658

Volume Percent DTBP or EHN0.0 0.5 1.0 1.5 2.0

NO

x Em

issi

on, g

/bhp

-h

4.5

4.6

4.7

4.8

4.9

5.0

Cert Fuel NOx

DTBP 2-EHN

Percent Change in PM versus No. 2 Diesel-20 -10 0 10 20

Perc

ent C

hang

e in

NO

x ve

rsus

No.

2 D

iese

l

-4

-2

0

2

4

B20

B20 + Timing Retard

1987 Cummins L101987 Cummins N14

300 350 400 450 500 550 600

3700

3750

3800

3850

-1.5

-1.2

-0.9

-0.6

-0.3

-0.15

0

0.15

0.3

0.6

0.9

1.2

1.5

max = 0.26 PPB min = -0.98 PPB

Difference in Daily Max 1-Hour Ozone (ppb)August 07, 1997

NREL Biodiesel -- 100% Penetration B20 Biodiesel minus Base

Does +2% NOx Matter?Air Quality Modeling•Impact of 100% market penetration of B20 on air quality in South Coast.•NOx from B20 use has no negative air quality impact (changes in ozoneless than 1 ppb).

•PM emission reduction showed no positive impact.•Study by Environ, for details see NREL/SR-540-33793, April 2003

Week End Ozone Effect•Study suggests uncertainty in air quality implications of small changes in NOx emissions•See EM, July 2003 pages 17 and 27

Biodiesel Oxidative Stability• Long-term tests show that biodiesel is

unstable to oxidation• Anti-oxidants can be effective, some

biodiesel contains natural antioxidants• B20 and B100 have different stability

issues• Issue of major concern to engine

manufacturers: deposits and acidity cancause reduced life or failure of components

Tota

l Aci

d N

umbe

r, m

g K

OH

/g

0.0

0.5

1.0

1.5

2.0

2.5

3.0

CL00-288CL00-289CL00-290Soy+Tenox-21

Inso

lubl

e, m

g/10

0 m

l

0

1

2

3

4

5CL00-288CL00-289CL00-290Soy+Tenox-21

Week

0 2 4 6 8 10 12 14 16 18

Visc

osity

@40

o C, c

St

3.5

4.0

4.5

5.0

5.5

6.0

6.5

CL00-288CL00-289CL00-290Soy+tenox-21

ASTM D4625 Standard Test for Distillate Fuel Storage, 43oC

Tota

l Ins

olub

les,

mg/

dLAc

id V

alue

, mg

KOH

/gVi

scos

ity@

40C

, cSt

0

2

4

6

8

10

12

Total Insolubles Acid Value Viscosity

Initial

ValuesUnadditize

d

Base Fuel BHTTBHQ

Tenox-21

Biodiesel Warranty Issues

•Manufacturers warrant their products against defects inmaterials and workmanship

•In general use of a particular fuel should have no effect on thematerials and workmanship warranty

•Use of biodiesel does not “void the warranty”, this is prohibitedby the Magnuson-Moss Warranty Act

•Manufacturers are concerned that extensive use of biodiesel willresult in increased numbers of warranty claims for what areactually problems caused by the fuel

Position Statements

Manufacturer: Position: Engine EMA Up to 5% biodiesel Caterpillar Many engines approved for use with B100, other limited to B5.

Must meet ASTM D6751. Cummins All engines approved for up to 5% biodiesel. Detroit Diesel Corporation Approve up to 20% biodiesel if produced from virgin soybeans

or rapeseed. Must meet DDC specific fuel specification. International No position on biodiesel specifically. John Deere All engines approved for 5% biodiesel if produced from

soybeans and meets ASTM D6751. Mack No specific position, fuel additives and extenders not

recommended. Volvo No specific position. FIE Bosch Up to 5% biodiesel accepted but must meet ASTM D6751. Delphi Up to 5% biodiesel accepted but must meet ASTM D6751. Stanadyne Up to 20% biodiesel accepted, must meet ASTM D6751.

Concerns about fuel quality and stability are what is preventingapproval of blending levels above 5% for most manufacturers

While manufacturers do not warrant fuel, many have position statementsand recommendations on biodiesel:

Summary•Truly renewable petroleum displacement fuel•Low biodiesel content blends (<5%) are fully compatible with fuel systemsand should not lead to durability or maintenance issues.

•20% biodiesel blends have some minor property and performancedifferences relative to conventional diesel:

•Possibly higher T90•Possibly poorer stability•~2% higher NOx emissions but significantly lower PM emissions

•Many manufacturers “are comfortable” with B20, but most prefer limitingbiodiesel content to 5% at present