4 June 2009
Navistar has challenged the US EPA 2010 emission regulations for heavy-duty diesel engines over the certification of competitor’s engines employing urea-SCR technology. While Navistar declined to comment on the law suit, documents filed by the company with US Circuit Court of Appeals for the District of Columbia from March to May 2009 were posted at eenews.net (see links below).
In 2001, when EPA issued the final rule outlining the 2007/2010 emission regulations, the agency envisioned that NOx adsorbers would be the main technology to comply with the 0.2 g/bhp-hr NOx emission standard. Urea SCR technology was not considered feasible by the EPA at that time, due a number of issues with establishing a nation-wide urea infrastructure and with replenishing the urea tank onboard of the vehicle (in the SCR technology, if urea solution is not injected upstream of the SCR catalyst, the engine NOx emissions remain uncontrolled).
When it became apparent that NOx adsorbers couldn’t meet the demands of the heavy-duty engine application on time, the EPA has changed its position on urea-SCR. In March 2007, the agency issued a guidance document on emission certification of engines equipped with urea-SCR technology (the document was last modified in February 2009). The guidance introduced a number of requirements that were not a part of the 2001 regulation—such as driver warning and “inducement” mechanisms to make sure that the vehicle cannot be operated with an empty urea tank. Navistar is arguing that the guidance document represents in fact an amendment of the 2001 emission regulation—as such it should be adopted through a proper rulemaking procedure and with the required regulatory stability periods.
Navistar is the only engine manufacturer who will comply with the 2010 standards without NOx aftertreatment, using advanced combustion methods, such as low temperature combustion (LTC). The combustion approach, however, involves the use of high EGR rates (sometimes referred to as “massive EGR”) and is generally believed to result in inferior fuel economy compared to the competing urea-SCR engines.
Earlier, Navistar called on EPA—without success—to allow sales of the less expensive, 2007-compliant engines into 2010 due to the economic situation. The continuing attempts by Navistar to delay the 2010 deadline seem to imply the company needs more time to refine its technology before the market launch.