Response to the NRC's 5th Peer Review Report Recommendations

RECOMMENDATION: The PNGV four-stroke direct-injection technical team should develop projections of the performance of compression-ignition direct injection and gasoline direct injection power-train systems, especially comparisons of the estimated emission and fuel economy for each system. These projections would be a first step toward the quantification of trade-offs between emissions and fuel economy based on current and emerging state-of-the-art technologies.

The 4SDI Technical Team agrees with the Peer Review Committee's recommendation and continues to quantitatively compare the projected performance (fuel consumption, emissions, cost, weight, performance, etc.) of various 4SDI powertrain alternatives with respect to the PNGV objectives. Some of these comparisons were made on a company proprietary basis, rather than collaboratively. The 4SDI Technical Team has been collaborating with the System Analysis Team on developing projections of the performance of compression-ignition direct-injection and gasoline direct injection power-train systems. Once the systems model has been validated, it would be an appropriate tool to use in quantifying the necessary trade-offs. The teams will present their results at the November 1999 Collaborative Peer Review.

PNGV recognizes there are potential trade-offs between emission and fuel economy targets. We believe EPA's proposed Tier 2 standards presents increased technical challenges to achieving PNGV's fuel economy goal with four-stroke direct-injection technologies. We believe the PNGV program should give increased emphasis to demonstrating 4SDI engines that achieve both Tier 2 emissions levels and the PNGV fuel efficiency goal.

RECOMMENDATION: The federal government agencies involved in the PNGV program should review how future emissions requirements (especially NOx and particulates), fuel economy, carbon dioxide emissions, as well as fuel quality, will affect the choice of the compression-ignition direct-injection engine as the most promising short-term combustion engine technology; a program plan that responds to that assessment should be developed. The PNGV, especially the U.S. Department of Energy and the Environmental Protection Agency, should work closely with the California Air Resources Board on these issues.

In response to pending Tier 2 federal emissions regulations, the PNGV partners have adopted a more aggressive R&D program to reduce NOx and particulate emissions from the CIDI engine while maintaining its inherently high efficiency and low carbon emission. Within the Low Emissions Partnership (LEP) lean NOx catalyst and non-thermal plasma cooperative research efforts, a new goal of 90 percent or greater NOx conversion is being considered and selective catalytic reduction (SCR) is being added to the NOx reduction strategies. Fuels and aftertreatment programs continue to be more closely linked to minimize in-cylinder emissions while optimizing the performance of new clean fuels as emission control reductants. Two new three-year cooperative agreements to develop emission control systems for the Ford and DaimlerChrysler PNGV engines have brought the expertise of catalyst suppliers more directly into the program. In addition, the DOE has been working with EPA, Engine Manufacturers Association (EMA) members and emission control manufacturers through the Diesel Emission Control Sulfur Effects (DECSE) project to determine the effects of sulfur in diesel on emission control devices,

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