EPA guidance on SCR: ICCT comments
Selective catalytic reduction (SCR) is the dominant technology used to meet nitrogen oxide (NOx) emissions standards for heavy-duty diesel vehicles in the United States, Europe, and Japan. In developing markets such as China and India, which are planning to implement Euro IV standards, SCR is also manufacturers’ preferred technology option. It allows for NOx control with little or no fuel-economy penalty, and can permit manufacturers to continue marketing the same engine/aftertreatment combination even as emission standards become tighter over time.
But SCR poses unique implementation challenges stemming from its reliance on a reducing agent (typically aqueous urea, though others can be used), which is injected into the exhaust gas upstream of the catalyst, and which must periodically be replenished. SCR requires an extensive urea delivery infrastructure for geographically dispersed mobile sources and robust failsafes to ensure that drivers properly fill onboard urea tanks. Under certain circumstances SCR-equipped vehicles in use may also pose problems with off-cycle and unregulated emissions due to the temperature dependence of catalytic activity, improper urea dosing, catalyst poisoning, and the formation of catalytic byproducts. Read more
Revising vehicle efficiency standards
Speed kills, goes the cliché. So does weight—kills fuel economy, that is, and most other important measures of vehicle performance. As Henry Ford himself said in 1924, “Excess weight kills any self-propelled vehicle. . . . Weight may be desirable in a steam roller, but nowhere else.” Designing heavier vehicles is a bad idea.
Ironically, it is the United States that has traditionally failed to heed Ford’s commonsense advice, from the days of tail fins and chrome to the SUV era, while the rest of the world has benefited from it. Read more
Global passenger vehicle fuel economy and GHG emissions standards: April 2010 update
• April 2010 update [PDF]
• Datasheet of global passenger vehicle FE/GHG regulations [.xlsx]
• Test cycle conversion tool [.xlsx]
• Charts [Download .ppt file]
The ICCT developed a methodology in its 2007 report to normalize the different driving test cycles adopted worldwide to allow apples-to-apples comparison of the global standards. The following is an update of the current status of these standards in various countries. Read more



