Southwest Research Institute® (SwRI®) News
Printer Friendly VersionGasRail USA reduces NOx by 75 percent
Technology is transferable to passenger and freight locomotives
May 29, 1998 -- San Antonio -- Southwest Research Institute® (SwRI®) engineers recently reported to members of the GasRail USA cooperative industry research project that they have achieved a 75 percent reduction in nitrogen oxide (NOx) emissions on a 4,200 horsepower, 16-cylinder, natural-gas fueled engine for use in passenger locomotives. The reduction is in comparison to a diesel-fueled engine.
GasRail USA was initiated in 1993 by SwRI, together with federal, state, and industrial participants. Their goal was to develop natural gas engine technology for locomotives and to demonstrate that using liquefied natural gas (LNG) fuel could contribute to lower NOx emissions. SwRI has extensive experience in converting heavy-duty diesel engines to natural gas and other alternative fuels.
"These emission levels make using LNG an attractive proposition for rail companies in noncompliance areas such as Southern California and parts of the Northeast, where diesel locomotives are an important feature of public transportation and contribute substantially to air pollution," says David Meyers, a group leader in SwRI's Engine and Vehicle Research Division and GasRail USA project manager. "A locomotive engine that produces approximately 12 grams of NOx per horsepower hour (g/bhp-hr) using diesel fuel only produces 2.8 g/bhp/hr using this new LNG engine technology.
"There is a small (8-10 percent) penalty in efficiency compared to diesel with the 75 percent reduction in emissions," adds Meyers, "but a 50 percent reduction in NOx can be achieved with no loss of efficiency. An additional benefit is that this engine creates no accompanying increases in carbon monoxide (CO) and hydrocarbon (HC) emissions. Carbon dioxide (CO2) emissions are actually reduced by 25 percent."
Six different LNG engine combustion systems were designed, tested, and evaluated for the GasRail program. The selected system, known as LaCHIP (Late Cycle High Injection Pressure), uses small amounts of diesel fuel as an ignition source for the high-pressure natural gas that is injected late in the combustion cycle. Diesel can also be used as an emergency fuel, allowing the locomotive to pull into a shop for repairs if the LNG supply is interrupted.
The LNG system will be field-tested in a Metrolink commuter locomotive owned by the Southern California Regional Rail Authority. Test runs between San Bernadino and Los Angeles in early 1999 will provide additional data on environmental and economic benefits, as well as prove LNG safety procedures.
The Environmental Protection Agency (EPA) in 1997 called for locomotives to meet a 25 percent reduction in NOx emission and a 40 percent reduction in HC and particulate matter emissions by the year 2000, with further reductions to follow by 2005. Current unregulated diesel locomotive emissions are estimated to contribute 5 percent of the national total emissions of NOx.
"This LNG technology will be easily transferable to heavier freight engines, where emissions are also of concern," says Senior Research Engineer John Hedrick. "We are confident that the system is capable of meeting stringent emissions standards in combustion-powered locomotives without resorting to electrification."
SwRI engineers are now working on the integration engineering phase of the prototype multi-cylinder engine. "Further tasks before installation in the test locomotive," says Hedrick, "include working on the transition phases between idle and full-power and evaluating the fuel switching technology from gas to diesel and vice versa."
Program participants in the GasRail USA program have included the Southern California Regional Rail Authority, the California Air Resources Board, the Southern California Air Quality Management District, the U.S. Department of Energy, the Gas Research Institute, Union Pacific Railroad, Amoco, and General Motors' Electro-Motive Division.
New members are welcome to join the consortium. For further information about GasRail USA, contact David Meyers at (210) 522-5581.
Related press release: Technical
breakthroughs reported in the use of natural gas locomotives
For more information about the GasRail USA program, contact Deborah Deffenbaugh, Communications Department, Southwest Research Institute, P.O. Drawer 28510, San Antonio, Texas 78228-0510, Phone (210) 522-2046, Fax (210) 522-3547.
