Clean-diesel proponent confirms fuel economy, environmental merits of SCR

Source: Diesel Technology Forum, Frederick, Md.

Growing adoption of clean diesel systems utilizing Selective Catalytic Reduction (SCR) technology is reducing emissions and increasing fuel efficiency in heavy-duty trucks and smaller vehicles, according to Diesel Technology Forum Executive Director Allen Schaeffer.


“SCR-based systems are helping manufacturers balance the competing goals of lower emissions and increased fuel efficiency. They are a ‘game-changer’ that helps ensure that clean diesel power is the technology of choice for the foreseeable future,” he told 7th Integer Emissions Summit USA participants, gathered in Chicago. Of the 250,000 new commercial heavy-duty trucks sold in 2014, he noted, more than more than 95 percent have SCR-equipped, clean diesel power.

An increasing number of engines, vehicles and equipment are utilizing SCR, and the systems are performing as designed and helping to slash the diesel fuel costs
for truck owners, Schaeffer observed. “In just about five months, the U.S. Environmental Protection Agency and National Highway Traffic Safety Administration will issue what is already a closely-watched proposal that will establish higher fuel efficiency requirements from commercial trucks in the years ahead,” he added. “This will be a main subject of conversation in the months ahead and we look forward to this open dialogue and discussion.”

Widely deployed in Class 8 trucks to meet sharply reduced EPA emissions and particulate matter thresholds for on-highway diesel engines from 2010 forward, SCR is an advanced, active emissions control method that injects a liquid reductant agent through a special catalyst into the exhaust stream. The reductant source is usually automotive-grade urea, otherwise known as diesel exhust fluid. The DEF sets off a chemical reaction that converts nitrogen oxides into nitrogen, water and tiny amounts of carbon dioxide, which is then expelled through the vehicle tailpipe.
SCR technology is designed to permit nitrogen oxide (NOx) reduction reactions to take place in an oxidizing atmosphere. It is called “selective” because it reduces levels of NOx using ammonia as a reductant within a catalyst system.  —