Ultra-Low Sulfur Diesel Coming to the USA

June 1 was the first day of implementation of the new "Ultra Low Sulfur" diesel fuel standards in the USA, but the new fuel and emission control systems won't be everywhere until 2010. By then, sulfur will be down to 15 parts per million (ppm) from its current 500 ppm, a 97% reduction. As far as we know, the major problem with having high quantities of sulfur in diesel fuel is that it makes emission-control equipment fail much faster and keeps automakers from installing the latest technology of pollution-control systems on their vehicles. This means that recent diesel vehicles that don't have the latest emission technology won't be much cleaner, but they won't degrade as much with time, and old diesel vehicles that have already been affected won't see much improvement. It is with 2007 model-year diesel vehicles that the difference will be seen (and smelled): They will have to meet the new EPA Tier 2 emissions specifications and be refuelled only with ultra-low sulfur diesel (ULSD). But lets not rejoice too fast, diesel - even ULSD - is still dirtier than gasoline. This new "clean" diesel is only clean compared to the old version. We'll breathe better when we start seeing diesel cars and trucks that meet SULEV and PZEV emission standards (or at the very least ULEV). The best way to reduce diesel pollution is still to ship less stuff over long distances - produce more locally - and to use trains instead of trucks. ::NRDC, ::Green Car Congress