Oct 1, 2008 12:00 PM, By David A Kolman

Urea

A major concern about the adoption of SCR is whether an infrastructure for urea will be in place by 2010.

Toward that end, a number of companies in the refining, packaging, and distribution segments of the nation's fuel market are preparing to provide diesel exhaust fluid availability.

Technology choices

Engine manufacturers are taking different approaches to meeting the more stringent 2010 US EPA-mandated diesel emission standards for their heavy-duty diesels.

Navistar is going with exhaust gas recirculation (EGR) technology for its MaxxForce engines.

Detroit Diesel, Mack, Paccar, and Volvo will be using selective catalytic reduction (SCR) technology.

Cummins will offer both EGR and SCR technologies.

Caterpillar, which recently announced it will exit the North American heavy-duty diesel truck engine market by 2010, will not be supplying 2010 compliant engines.

Clean air

On the federal level, the EPA has regulated on-highway diesel engine emissions standards through the Clean Air Act (CAA) since 1970. Emission regulations are phased in over a number of years, gradually reducing the legal levels of emissions for various sizes of diesel engines.

These phases are identified as Tiers. The higher the Tier level, the greater the reduction in emissions.

Tier 3 emission standards will take effect in 2012, followed by Tier 4 in 2015.

The EPA estimates that Tier 3 standards will reduce NOx emissions from diesel engines by about 1 million tons per year, an effect similar to taking 35 million passenger cars off the road. Tier 4 standards are even more rigorous.

In the European Union, emissions standards are identified as Stages or Euro standards. Euro 4 standards were implemented in 2006, setting PM emissions at 3.5 gram per kilowatt-hour (g/kWh) and NOx emissions at 0.02 g/kWh.

Euro 5, which goes into effect in 2009, calls for a nearly 43% reduction in NOx emissions to 2.0 g/kWh. PM remains unchanged.

Euro 6 requirements, which will come around 2013, are still being decided upon. It is expected, however, these regulations will decrease emissions of PM by 50% and NOx about 75% to 80%, compared with Euro 5 standards.