Last year, the US EPA (Environmental Protection Agency) and DOT (Department of Transportation) proposed the first-ever fuel efficiency and vehicular gas emissions standards for medium- and heavy-duty trucks and buses, many of which use diesel.
According to the American Council for an Energy-Efficient Economy (www.aceee.org),“the affected vehicles, ranging from large pickup trucks to big rigs, today consume about 2.5 million barrels of crude oil equivalent per day, one-fifth of total US transportation crude oil use.” EPA standards are published in the Congressional Federal Registrar, 40 CFR Part 86, with a detailed discussion of these standards to be found at www.dieselnet.com/standards.
In order to meet 2010 EPA emissions standards for highway diesel trucks and buses (www.factsaboutscr.com/scr) Diesel Exhaust Fluid (DEF), a 32.5 percent automotive grade urea solution in deionized water, is used in diesel engines with SCR (selective catalytic reduction) technology. Automotive grade urea, which is produced from the reaction of carbon dioxide and ammonia, meets ISO 22241 and industry established performance requirements for DEF quality, testing methods, handling, transportation and storage, and refilling. Typically, about two gallons of DEF solution is injected in the catalyst for every 100 gallons of diesel, although manufacturers’ usage may be lower or higher depending on engine technology and duty cycle. About 70 percent of new diesel trucks brands (e.g. Mack Truck) use DEF with the remaining share using alternative technology. In addition to meeting the new vehicular emission standards, the use of DEF improves diesel engine fuel efficiency by as much as five percent, net of costs.
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