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ACES study demonstrates ultra low emission levels in US 2007 engines

18 June 2009

US 2007 heavy-duty diesel engines produce pollutant emissions well below the regulated levels, according the Advanced Collaborative Emissions Study (ACES) released today by the Coordinating Research Council (CRC). The ACES study—the most rigorous emissions testing ever done for new heavy-duty diesel engines—was managed and designed by the Health Effects Institute (HEI), and emission testing was performed by the Southwest Research Institute.

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The Phase 1 Report of the ACES study found that PM emissions were nearly 90% lower than the 2007 emission standard for heavy-duty diesel vehicles, and 99% lower than PM emissions from 2004 engines. Emissions of CO, HC, and a number of unregulated air toxics were also more than 90% lower than the 2004 levels and substantially below required levels. NOx emissions were approximately 70% lower than in the past and 10% below the regulatory limits. Another approximately 80% reduction in NOx is required from 2010.

The Phase 1 ACES study tested four heavy-duty diesel engines manufactured by Caterpillar, Cummins, Detroit Diesel, and Volvo. Emissions were characterized over the FTP transient test, over several CARB 5-mode cycles, as well as over a specially developed 16-hour cycle which included four 4-hour segments consisting of FTPs and CARB 5-modes. The engines were tested on multiple iterations of the cycles. Over 300 regulated and unregulated air pollutants were measured. Most measurements were performed with engine blow-by routed to the exhaust downstream of the DPF. Average emissions of regulated pollutants are summarized below.

ACES Average Regulated Emissions (FTP Cycle with Blow-By)
Pollutant2007 EPA Standard, g/bhp-hrACES Emissions, g/bhp-hrReduction below 2007 Standard, %

ACES is a multi-party five year study to test the emissions and health effects of new technology diesel engines to document the improvements that have been made and to ensure that there are no unintended emissions from this new technology. The study is being undertaken by the HEI and the CRC with support from a wide range of government and private sector sponsors, including the US Department of Energy, US Environmental Protection Agency, California Air Resources Board, Engine Manufacturers Association, American Petroleum Institute, and manufacturers of emission control equipment.

The report issued today summarizes the results of Phase 1—the emissions characterization of representative 2007 model year heavy-duty diesel engines. Detailed short and long term laboratory health testing of emissions from one of the four representative engines tested in Phase 1 has been started at the Lovelace Respiratory Research Institute in Albuquerque, New Mexico, with initial results expected in 2010. A Phase 2 of the ACES study, to test the 2010 engines, is in planning.

Source: HEI