EPA sets guidelines for SCR engines

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The U.S. Environmental Protection Agency has issued guidelines for engines using selective catalyst reduction to meet 2010 federal emissions standards. The reducing agent must be readily available, the agency says, and drivers must be warned automatically if their tanks are low on it.

SCR reduces emissions of the ozone-forming pollutant nitrogen oxide, or NOx, by injecting a reducing agent, usually ammonia or urea, into the exhaust gas upstream of the catalyst. Drivers must replenish the agent periodically, or NOx emissions can increase greatly.

Because of this, the EPA says, engines using SCR must have a way of alerting the driver that the agent is low. They also must have a backup system to prevent the driver from operating the truck despite the warning – for example, a fuel lockout that makes refueling impossible if the urea tank is empty.

Urea also must be readily available at truck stops, dealerships and retail stores, the EPA says. The agency says it must approve all SCR designs, which must be durable and tamper-resistant, and must provide ways to identify an incorrect reducing agent.

After reviewing the EPA guidelines, Volvo Trucks North America expressed its appreciation for the guidance, which it considers an important step in the effort to bringing the SCR technology solution to market.

“We are convinced that SCR is the best choice for continuing to dramatically reduce diesel engine emissions in 2010, while delivering optimal performance and fuel efficiency for our customers,” says Peter Karlsten, Volvo Trucks North America president and chief executive officer. “The EPA has provided an important guide for the many stakeholders working to address the urea infrastructure and other issues necessary to bring this clean diesel technology to the North American market.”

Mack Trucks also characterized the guidance as a key step in the ongoing effort to dramatically reduce diesel engine emissions. “This document is a critical guideline for the many stakeholders dedicated to bringing this important emissions control technology to the United States,” says Paul L. Vikner, Mack president and CEO. “We are convinced that in addition to its environmental benefits, SCR will deliver the fuel economy, reliability and performance Mack customers demand, and we’re committed to working with the EPA, the truck industry and other stakeholders to ensure that the infrastructure is in place to support this solution.”

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Mack says it has been running SCR systems on prototype trucks successfully since 2000, logging more than two million miles on 10 customer vehicles.