v>EPA United States Environmental Protection Agency Air and Radiation EPA420-F-96-009 July 1996 Office of Mobile Sources Environmental Fact Sheet Control of Emissions From Nonroad Engines In response to environmental and public health concerns, the U.S. Environmental Protection Agency (EPA) is establishing emission standards for a number ofnonroad engine categories. EPA's first standards for diesel-fueled nonroad engines greater than 50 horsepower began to take effect in 1996. These engines are typically used in farm, construction, material handling and logging equipment. Over the past year, EPA has been working with the California Air Resources Board (CARB) and nonroad engine and equipment manufac- turers to agree upon a "Statement of Principles" (SOP) that would propose future standards for this category of diesel- fueled nonroad engines as well as for the currently uncon- trolled gasoline- and propane-fueled nonroad engines above 25 horsepower used in similar applications. History of Nonroad Controls Emissions from engines used in nonroad equipment are a significant source of oxides of nitrogen (NOx), volatile organic compound (VOC) and particulate matter (PM) emissions. Emissions from nonroad engines can be particularly troublesome as nonroad equipment often operates in urban areas, potentially exposing large numbers of people to harmful pollutants. In some areas of the country, emissions from nonroad engines represent a third of the total mobile source NOx and VOC inventory and over two-thirds of the mobile source PM inventory. ------- The 1990 Clean Air Act Amendments specifically directed EPA to study the contribution of nonroad engines to urban air pollution, and regulate them if warranted. In 1991, EPA released a study that documented higher than expected emission levels across a broad spectrum of nonroad engines and equipment. In response, EPA initiated several regulatory programs for nonroad engines. One of these programs set emission standards for diesel-fueled nonroad engines greater than 50 horsepower, which is being phased in from 1996 to 2000. Under these standards, EPA projects that NOx emissions from new diesel-fueled nonroad equipment will be reduced by 37 percent. Tighter National Emission Standards EPA and CARB have been meeting with nonroad engine and equipment manufacturers over the last year to develop a nonroad SOP that will propose tighter emission standards and other provisions for nonroad engines manufactured after 2000. For the purposes of this SOP, "nonroad" primarily refers to applications such as farm, construction, material handling, and logging equipment. EPA and CARB hope to reach agreement on the nonroad SOP during the summer of 1996. EPA expects to issue a Notice of Proposed Rulemaking (NPRM) to formally propose the new emission standards contained in the nonroad SOP in early 1997. EPA expects that the NPRM will cover all sizes of diesel-fueled nonroad engines, and those gasoline-fueled and propane-fueled nonroad engines above 25 horsepower. (Other nonroad applications, such as recreational boats, locomotives, and smaller gasoline-fueled nonroad equipment, are being addressed in separate EPA initiatives.) Nonroad Engine Technology Many nonroad engines are diesel-fueled compression-ignition engines. Diesel engine technology has continually improved over the past twenty-five years, resulting in increasingly fuel efficient, reliable and durable engines. Controlling NOx and PM emissions presents a special challenge for the diesel engine industry, however. The high cylinder temperature typical of diesel combustion causes nitrogen and oxygen from the intake air to combine as NOx. Due to the unique fuel and combustion chemistry of diesel engines, PM emissions are also inherently higher than emissions from comparable gasoline engines. Control technologies that reduce NOx may increase PM, adding to the technological challenge. -2- ------- Because many engines used in highway trucks are similar to those used in nonroad equipment, it is likely that highway diesel engine control technologies will be transferred to nonroad applications to comply with tight standards. However, many of the emission control strategies currently used in highway diesel engines may require further development for nonroad applications because nonroad equipment has different operating characteristics and chassis restrictions than do the highway counterparts. For example, highway engines can utilize the cooling properties of high vehicle speed, an advantage not available for nonroad equipment. Additionally, nonroad engines are often made for a wide range of applications so engine and chassis design changes are not as readily integrated, resulting in added complications. For nonroad gasoline-fueled and propane-fueled engines, it is expected that emission control technologies that are well-established in the automotive industry, such as exhaust gas recirculation, closed- loop fuel control, and catalytic converters, may find application. For More Information For more information on this program, please call the NOx/PM Initiative voice mailbox at (313) 741-7887, or write to: U.S. Environmental Protection Agency National Vehicle and Fuel Emissions Laboratory NOx/PM Initiative - Nonroad Team Engine Programs and Compliance Division 2565 Plymouth Road Ann Arbor, Michigan 48105 The Office of Mobile Sources also has information available on the EPA Internet server and via dial-up modem on the Technology Transfer Network (TTN), an electronic bulletin board system (BBS). World Wide Web: http://www.epa.gov/OMSWWW TTN BBS: 919-541-5742 (1200-14400 bps, no parity, 8 data bits, 1 stop bit); voice helpline: 919-541-5384 -3 - ------- |