SwRI testing shows APUs reduce exhaust emissions from locomotives

Exhaust emission tests conducted at the SwRI San Antonio facility show a 91 percent reduction in oxides of nitrogen (NO_x), a 94 percent reduction in hydrocarbon (HC), a 96 percent reduction in carbon monoxide (CO), and an 84 percent reduction in particulate matter (PM) when compared to main-engine idle emissions. Use of the APUs also netted an 83 percent savings in fuel consumption during idle, which translates to savings of about $12,500 per year for each locomotive used in switcher service based on diesel fuel costs of 80 cents per gallon.

In August, SwRI initiated the second part of the program by monitoring in-service operation of two modified 2,200 hp switcher locomotives in the Houston-Galveston area for one year. The Institute installed data loggers on the locomotives to monitor the amount of main engine idle time, the amount of engine shut off time by the APU controller, and the use of the APU.

Large engines such as locomotive engines must idle for various reasons including difficulty with cold-engine startup and the need to provide continuous internal temperature controls, such as heating or air conditioning. Switcher locomotives typically idle about 60 percent of their operational time.

"The locomotives are equipped with a GPS tracking device to quantify the emissions reductions in the Houston area," said Steve Fritz, principal engineer in the SwRI Automotive Products and Emissions Research Division. The Houston-Galveston region is a non-attainment air-quality area.

New locomotive emissions standards from the Environmental Protection Agency (EPA) are designed to significantly reduce emissions and help provide cleaner air. Prior to 2000, locomotive emissions were not regulated. New regulations aspire to reduce NO_x by 60 percent by 2040, compared to 1995 baseline rates. The Texas Emission Reduction Plan (TERP), established in 2001 by the Texas legislature and administered by the Texas Commission for Environmental Quality (TCEQ), provides grants and incentives for improving air quality in the state. TCEQ provided a $285,000 grant to the APU manufacturer for the demonstration program, which included the installed cost of the APUs, exhaust emission testing of the two locomotives including both the main 2,200 hp diesel engine and the APU engine, and the yearlong field monitoring of the modified switcher locomotives.

The Institute has more than 30 years of locomotive engine research experience. The SwRI Locomotive Emissions Test Center was established in 1990 in response to a need by the Association of American Railroads for locomotive exhaust emission testing capabilities. To date, the Institute has tested more than 70 locomotives at the center.

For more information about SwRI's work with locomotives, visit the web site at locomotivetesting.swri.org or call Fritz at (210) 522-3645.

For more information, contact Tracey M.S. Whelan, Communications, (210) 522-2256, Fax (210) 522-3547, PO Drawer 28510, San Antonio, Texas 78228-0510.

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