MTU / Rolls Royce released their new Tier III certification today for the 4000 series motors with parameters and associated ancillary SCR equipment required in new installations. The size of the selective catalytic reduction modules needed per engine are going to drive builders and machinery space design engineers nuts. Machinery spaces are getting smaller and smaller with interior designers taking a frame here and a frame there for accommodation's. With the different types of exhaust treatment available today it seams odd that MTU would choose this method of treatment with the onerous equipment and the needed hauling and storing of aqueous ammonia or urea aboard. I'm certainly not an authority on this subject but have been around DPF (diesel particulate filter) systems such as Halyards systems and while these systems are maintenance heavy with cleaning particulate filters they're relatively small in comparison to this urea system pictured. YF does have an expert in this field that manufactures a type of DOC ( diesel oxidation catalytic system) on generators and has great success in doing so. If I was a naval architect that had to fit this new MTU SCR equipment aboard a new build 60 meter vessels machinery space it might well lead me to drink the urea.