Tier 4 and urea

The U.S. and EU are soon to implement the final tiers in their emissions control standards for highway and off-highway diesel engines. In the U.S., final Tier 4 regulations, which will be fully implemented by 2015 for farm tractors and a few years earlier for highway trucks, call for a 90 per cent reduction in NOx emissions from Tier 3 standards. (This chart, from the John Deere website, describes the whole emissions reduction process simply and thoroughly. Click on it to enlarge.)

What's interesting to me is that the leading method to achieve these standards in highway trucks uses urea to break down nitrous oxides (NOx).  This system is already in use in Europe, using a urea product called AdBlue. Here's a description of how it works, taken from the AdBlue website:

"AdBlue is a solution of urea in water (32.5 per cent), which is used in lorries that use diesel oil, in order to have them run with less impact on the environment. AdBlue is taken on board the lorry in a separate tank. AdBlue is injected into the hot exhaust gases before a special catalyst. The nitrogen oxides that form during the combustion are converted into elementary nitrogen and water."

New on-highway trucks sold in the U.S. in 2010 and beyond will have to be Tier 4 compliant, which means service stations will have to start carrying urea. A truck will use two or three litres of urea for every 100 litres of diesel. From what I hear, the urea required from the truck market will be a small percentage of the total supply, but it means more demand for urea nonetheless.