Navistar claims loopholes in urea-based SCR

El Monte, Calif.-Navistar International Corp. is reporting that the U.S. Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) are taking a look at ways to close compliance loopholes in 2010 urea-based Selective Catalytic Reduction (SCR) systems, including that vehicles are able to operate for long periods with empty urea tanks. Navistar, which has its own Exhaust Gas Recirculation Nitrogen Oxide (EGR NOx) control system, said the findings are backed up by independent testing that shows that new commercial vehicles that must use liquid urea to meet federal NOx emissions standards can operate effectively when urea is not present, and at the same time vehicles throw off levels of NOx as much as 10 times higher or more than when urea is present. Navistar said the research was conducted by EnSIGHT, an independent environmental consulting firm, using two long-haul vehicles and one heavy-duty pickup, all of which use SCR technology. “Navistar first identified these loopholes to the agencies and also presented our concerns at a July 20 workshop here,” reported Jack Allen, president of Navistar’s North American truck group. “We will be working with the EPA and CARB to ensure full environmental compliance. It’s obvious, however, that these trucks can operate effectively without liquid urea, and that under these and other conditions, SCR NOx emission control is turned off. We’re calling on the EPA and CARB to assure that all vehicles, not just ours, work when they are supposed to be working.”