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The DOE Office of Heavy Vehicle Technologies (OHVT) and its predecessor organizations have maintained aggressive projects in diesel exhaust aftertreatment since 1993. The Energy Policy Act of 1992, Section 2027, specifically authorized DOE to help accelerate the ability of U. S. diesel engine manufacturers to meet emissions regulations while maintaining the compression ignition engines inherently high efficiency. A variety of concepts and devices have been evaluated for NOx and Particulate matter (PM) control. Additionally, supporting technology in diagnostics for catalysis, PM measurement, and catalyst/reductant systems are being developed. This paper provides a summary of technologies that have been investigated and provides recent results from ongoing DOE-sponsored R&D. NOx control has been explored via active NOx catalysis, several plasma-assisted systems, electrochemical cells, and fuel additives.

This paper describes the results of Phase 1 of the Diesel Emission Control - Sulfur Effects (DECSE) Program. The objective of the program is to determine the impact of fuel sulfur levels on emissions control systems that could be used to lower emissions of nitrogen oxides (NOx) and particulate matter (PM) from vehicles with diesel engines. The DECSE program has now issued four interim reports for its first phase, with conclusions about the effect of diesel sulfur level on PM and total hydrocarbon (THC) emissions from the high-temperature lean-NOx catalyst, the increase of engine-out sulfate emissions with higher sulfur fuel levels, the effect of sulfur content on NOx adsorber conversion efficiencies, and the effect of fuel sulfur content on diesel oxidation catalysts, causing increased PM emissions above engine-out emissions under certain operating conditions.

The Office of Heavy Vehicle Technologies supports research to enable high-efficiency diesel engines to meet future emissions regulations, thus clearing the way for their use in light trucks as well as continuing as the most efficient powerplant for freight-haulers. Compliance with Tier 2 emission regulations for light-duty vehicles will require effective exhaust emission controls (aftertreatment) for diesels in these applications. Diesel-powered heavy trucks face a similar situation for the 2007 regulations announced by EPA in December 2000. DOE laboratories are working with industry to improve emission control technologies in projects ranging from application of new diagnostics for elucidating key mechanisms, to development and evaluation of prototype devices. This paper provides an overview of these R&D efforts, with examples of key findings and developments.