Final Report Rochester Vehicle Fleet Alternative Fuels Systems Study

In air quality testing inside the Keene NH Recycling Facility, they achieved a
reduction of 50% when using B20 instead of regular diesel. The employees reported
that the headaches they had experienced, while working in this confined area with
diesel fumes, had gone away once the B20 was used. In addition, the Keene biodiesel
program, with 68 vehicles running on B20, has eliminated approximately 417 tons of
CO2 annually since program inception.
The PA Turnpike Commission, with the assistance of the U.S. EPA, conducted
emissions testing on a group of its vehicles that had been running on B20. The results
of these tests indicated that NOx emissions in the biodiesel( B20) test group had NOx
emissions that were equal to, or in some cases lower than the test vehicles that were
using conventional diesel fuel. The lower emissions seemed to correlate with newer
vehicles, which would support the conclusion that the changes in engine technology
had a positive effect on these results. Despite these test results in this fleet, the
general concern about increased NOx emissions with biodiesel blends is one of the
few notable disadvantages attributed to biodiesel fuel.
NOX Issue
The generally held notion regarding biodiesel and NOx is that B100 raises NOx
approximately 10%, and that biodiesel blends raise NOx in proportionately based on
that factor (i.e. B20 2%, etc.). Since Rochester is currently in non-attainment for
NOx, this property of biodiesel is of the greatest interest, though this non-attainment
status may be modified during 2007. 20 The National Biodiesel Board’s Fuel Fact
Sheet makes reference to this emissions characteristic, and references the USEPA’s
study “A Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions”. 21
However, based upon information raised during the subject area executive briefings
as noted above, the Fleet Counselor Team pursued information related to further
testing on biodiesel exhaust characteristics, and found very interesting feedback from
the U.S. Department of Energy’s National Renewable Energy Laboratory, which
performed a further analysis of the EPA study, and further conducted dynamometer
chassis emissions testing.
Their findings have been published as the “Effects of Biodiesel Blends on Vehicle
Emissions”, (Fiscal Year 2006 Annual Operating Plan Milestone 10.4), by
McCormick, Williams, Ireland, et. al. of the National Renewable Energy Laboratory.
To summarize, the EPA data set was heavily skewed by testing of a particular engine
model, and the new NREL study intended to address that via a reexamination of
previous studies, combined with further vehicle testing. The findings were that there
was variation between biodiesel emissions of NOx from both engine types, as well as
vehicle type, and duty cycle. Certain engines did show an increase, while others
showed a slight decrease, while others evidenced no net change. Though the vehicles
tested were not generally of the type present in the City Fleet (transit buses, motor
20
Op. cit #2.
21 http://www.nbb.org/pdf_files/fuelfactsheets/emissions.pdf
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Final Report