Urea Tank May Soon Be Required For Diesel-Powered Vehicles

Looks like "pissing in the pot" will be taken literally now ;-)
The good side of this, no longer need pee breaks on a long road trip to save
time.
-------------------- Starting in 2010, owners of diesel-powered cars and trucks may have to fill a supplementary tank with urea, an organic compound that fights nitrogen oxide emissions when it's injected into a vehicle's exhaust system, The Washington Post reports. In anticipation of vehicle makers adopting an emissions-reduction system that depends on urea to meet tight diesel pollution-control rules, the Environmental Protection Agency issued guidelines on March 27 telling manufacturers how to earn certification for the new engines. The agency wants to ensure that urea is easily available and that systems will be designed to force owners to keep tanks full.
Companies must design a system that would meet Clean Air Act rules by 2010 calling for the virtual elimination of nitrogen oxides and compel owners to maintain emission-control systems.
According to The Washington Post, the EPA cautioned that the systems must be designed so they can't be disabled, tampered with or filled with something other than the proper concentration of urea.
http://www.fleet-central.com/bf/t_inside.cfm?action=news_pick&storyID (374
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They have been talking about this for a few years and it applies to diesel owners Diesels are very big NOx generators as one diesel SUV makes as much or more NOx as about 10 gas powered ones. When the urea solution is injected into exhaust flow it converts to ammonia (NH3) and then via a SCR "CAT" it breaks down the NOx into water vapor and plain nitrogen (Nx) There are few other methods out there but this seems to be most popular. You are only becoming aware of this problem now because diesel have had a free "lead" in this area for many years and now are being brought into compliance. Gas motors have been complying for over 30 years now. ----------------- TheSnoMan.com
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SCR for NOx control is currently used on stationary diesel engines, and has been proposed for mobile applications. SCR uses ammonia as a NOx reducing agent. The ammonia is typically supplied by introducing a urea/water mixture into the exhaust upstream of the catalyst. The urea/water mixture is stored in a separate tank that must be periodically replenished. These systems can be very effective, with NOx reductions of 70 to 90%, and appear to be tolerant of current U.S. on-highway diesel fuel sulfur levels. However, there is concern that applying current SCR technology to highway vehicles will require use of catalyst formulations that are sensitive to sulfur, such as those employing platinum, to deal with the broad range of operating temperatures typical of highway diesel engines in use. There is also potential for formation of ammonia sulfate, which is undesirable because it is a component of fine PM28
In addition, SCR systems bring some unique concerns. First, precise control of the quantity of urea injection into the exhaust, particularly during transient operation, is very critical. Injection of too large of a quantity of urea leads to a condition of ``ammonia slip'', whereby excess ammonia formation can lead to both direct ammonia emissions (with accompanying health and odor concerns) and oxidation of ammonia to produce (rather than reduce) NOx. Second, there are potential hurdles to overcome with respect to the need for frequent replenishment of the urea supply. This raises issues related to supply infrastructure, tampering, and the possibility of operating with the urea tank dry.
Third, there may be modes of engine operation with substantial NOX generation in which SCR does not function well. Finally, there is concern that SCR systems may produce N2O, a gas that has been associated with greenhouse-effect emissions.
http://www.epa.gov/fedrgstr/EPA-AIR/1999/May/Day-13/a11383.htm
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Anyone know the NOX issues of biodiesel fuel compared to petroleum diesel?
Bill
wrote:

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