The Effects of Biodiesel Fuel Blends on Exhaust Emissions From a General Electric Tier 2 Line-Haul Locomotive

This paper documents the exhaust emission test results from a Tier 2 General Electric ES44DC line-haul locomotive with 3280 kW rated traction power and the impact of biodiesel fuel blends on regulated exhaust emissions. Baseline exhaust emission testing was performed with a test fuel containing a sulfur concentration of approximately 400 ppm and was followed by testing of fuel blends containing 2%, 10%, 20%, and 100% soybean derived biodiesel (B2, B10, B20, and B100). Gaseous and particulate emissions were sampled per Title 40 of the United States Code of Federal Regulations, Part 92. Test results indicate particulate matter (PM) reductions occurred over the Environmental Protection Agency (EPA) locomotive line-haul and switch duty cycles for each biodiesel blend tested, as compared with the base fuel. The bulk of the PM reduction benefit was present with the 10% biodiesel blend, with comparatively small additional amounts of PM reductions found with increased amounts of biodiesel. PM reduction associated with biodiesel was greater over the switch duty cycle than for the line-haul duty cycle. The change in cycle weighted oxides of nitrogen $(NOx)$ for B2, B10, and B20 was not greater than the expected test measurement variation; however, B100 increased $NOx$ by nearly 15% over the line-haul cycle. Changes in hydrocarbon (HC) emissions over the duty cycles were within normal test measurement variation except for neat biodiesel, where HC was reduced by 21% and 24% over the line-haul and switch cycles, respectively. Carbon monoxide reductions of 17% and 24% over the line-haul cycle were measured for B20 and B100, respectively, as compared with the base fuel. Volumetric fuel consumption increased to about 1% for both B2 and B10 blends. Just over 2% increase in volumetric fuel consumption was observed at B20 and nearly 7% increase in volumetric fuel consumption at B100.