Biodiesel and Pollutant Em

Bob McCormickWith: Aaron Williams, John Ireland, Bob HayesNational Renewable Energy LaboratoryGolden, ColoradoSeptember 28, 2006NREL/PR-540-40752Presented at the 2006 Texas Biodiesel

Conference and Expo held in Austin, Texas on Sep
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Results From Three Meth

Testing B20 for NO

x Emi

• Engine

– 2 % increase

• Chassis

– 0% average change

• PEMs

– No change or decreasing

Laboratory

Real-World
Engine Dynamometer T

•Test used to certify compliance with regulatio•Bare engine is connected to large electric gen•Operated over a range of speeds and loads•Emissions are reported in g/bhp-h

•weight per unit of work done by the engine

Engine

D
Biodiesel’s Effect on Em

Engine Compliance Test 

EPA data compilation:

•data from many studies•engine models through 

1997

•NO

x

•2% up for B20•10% up for B100

•PM

•12% down for B20•48% down for B100

EPA420-P-02-001, October 2002
95% Confidence Interval

B20 = +2%, B100 = +10%

Biodiesel’s Effect on NOx E

-Engine Data

EPA420-P-02-001, Draft Report, October 2002

• 4• 7• 9
Emission Benefits of 

• Broad agreement on reductions 

reductions

– 10 to 25% reduction in PM, depen

engine, test cycle, and other facto

• Impact on NO

x emissions less u

– EPA compilation of published data 

causing NO

x to go up ~2%

– But many studies in the review sh

down

– Not all newer studies show NO

x go

• Definitive conclusion for NO

x req

representative dataset
A Second Way to Measure 

• Test entire vehicles

– More realistic than engine 

testing

• HD chassis dynamometer

– 2007 CFR Emissions 

Measurement Capability

– 8,000–80,000 lb Range– Augmented Braking– Grade Simulation– Automated Coast-Downs

Gearbox Gearb

adjustable
Data from EPA420-P-02-001, October 2002

Percent Biodiesel

0 20 40 60 80 100

Percent Change in NO

x Emission

-15-10

-5

05

1015

Biodiesel’s Effect on NOx E

-Vehicle (Chassis) D

•EPA compilation also included published vehicle test •For these vehicles, on average, biodiesel has no impa

•Slope is not statistically significant (p=0.5)

Standards Group 

B 

C D 

E 

F 

G 

H 

I 

8 pick3 tran
Vehicle Engine MY Cycle NOx % 

1 Cummins ISM Transit Bus 2000 CSHVC 

2 Cummins ISM Transit Bus 2000 CSHVC 

3 Cummins ISM Transit Bus 2000 CSHVC 4 Cummins ISM Class 8 2005 CILCC 

4 Cummins ISM Class 8 2005 WVU Interstate 5 International Green Diesel School Bus 2005 RUCSBC 5 International Green Diesel School Bus 2005 CSHVC 6 Cummins ISB Motorcoach 2003 CSHVC 6 Cummins ISB Motorcoach 2003 UDDS 

7 DDC S60 Class 8 2000 CSHVC 

7 DDC S60 Class 8 2000 WVU Interstate 

8 International 7.6L School Bus 2004 CSHVC 8 International 7.6 L School Bus 2004 RUCSBC 

NREL Vehicle Testing Su

• Average change in NOx for B20 use is 0% 

– No statistically significant change (less than +/- 0.4%– Versus +2% in EPA analysis

• Magnitude and direction of NOx impact is cycle dep

• Average change in PM for B20 use is -21%

– Versus -12% in EPA data compilation

*Vehicle equipped 
A Third Way to Measure Em

PEMS

• Portable Emissions Measurement 

System

– On-board vehicle– Measures emissions during normal 

operation

• Probably the most real-world

emission measurement

• Basis for new EPA inventory 

model MOVES
Results of PEMS Stu

• North Carolina: 12 Dump Trucks

– Measured on NO, not NO+NO

2

– NO was reduced by 10% on average– http://www.ncdot.org/doh/preconstruct/tp

ad/2004-18FinalReport.pdf 

• New Jersey: 3 School Buses

– NO

x increased in some buses, decrease

– SAE 2005-01-1616

• Texas: 5 School Buses

– Compare TxLED, B20 (market), B20 (so– B20 had on effect NO

x

– Texas Transportation Institute at Texas A
Biodiesel Effect on N

•NO

x can go up or down depending on engin

–This is not well understood quantitatively–May be a driving cycle effect i.e. engine different speed a load points on different 

•Very limited dataset: Neither engine nor vehinclude a representative sample of in-use en

–Lack of representative sample may also perceived difference between engine and 

•Based on the additional data available today

–B20 appears to have no significant or coon NO

x emissions

•Reduction in PM and other pollutants is robu
Results From Three Meth

Testing B20 for NO

x Emi

• Engine

– 2 % increase (EPA review)– 0% change (newer studies)

• Chassis

– 0% change (EPA review)– 0% newer (newer studies)– 0% change (NREL study)

• PEMs

– 0% change

Laboratory

Real-World