This is how it works - supposidly
The application is an advanced form of Urea SCR, the benchmark NOx control technology. An advanced urea injection system meters precise amounts of a safe, non-toxic and easy-to-use urea solution into the exhaust stream of the diesel or natural gas engine. Once in the exhaust, the urea decomposes and forms ammonia which reacts with the NOx across the catalyst to convert the NOx into nitrogen and water.