MTU 4000 series Tier III certification

As they said in Jaws, " You're gonna need a bigger boat." All kidding aside, I'm sure a system can be designed smaller, if not more custom that a "stock" MTU SCR to fit somehow in the engine room. All of this will also generate heat, which means it will need to be insulated. It will most likely add to the overall backpressure meaning the exhaust would have to grow in diameter to compensate.

So who ever would supply a "smaller' and 'custom" SCR Aftertreatment System would have to re-certify the application to EPA T4 standards. Who is going to pay for the testing/certification for a one off? Who can legally own the EPA Certification other than an engine manufacturer?

Is this any different than CAT?: https://www.cat.com/en_US/by-industry/marine/USEPATier4FinalMarineEmissions.html

Or Cummins?: https://www.cummins.com/news/releas...ier-4-qsk38-clean-diesel-engine-international

The DOC reference to much smaller gensets are not an accurate comparison for larger class (liters/cylinder) and output (kW). The EPA rules do vary on engine size and emissions requirements.

CAT has a brief discussion on the topic here: https://www.cat.com/en_US/by-industry/marine/USEPATier4FinalMarineEmissions/tier-4-faq.html

I have seen the CAT and Cummins SCR units at trade shows, they should have their SCR Systems on display at the Workboat Show in December. The DOC Systems deal more with Particulate Matter than in cylinder combustion.

Please allow me a few comments on this subject based on personal experience. This system is available since 2016 and works pretty well in my present boat. 2 x MTU 16 V 4000 M 53 R with the SCR and Soot Filter System like in the picture above. The only difference is, the exhaust cleaning system is mounteed the other way around and sits above the engine. A similar smaller system is used for the two generators. All diesel engines in the engine room are connected to dry exhaust stacks which end up at the top of the mast. As the engine room of a 200 ft yacht is typically occupying two decks, installation height is not a problem.

The yard had some concerns about the heat radiation of the 16 Cyl. engine during the design phase, as they were used to Cat 3516 engines for this type of application. As this engine radiates much more heat from the top of the engine block, they were usually building an exhaust hood above the 3516 and 3512 engines. This would have caused problems as far as available space for the SCR sytem above the engine is concerned.

But the MTU 16V 4000 with the M53R Rating (continuous duty) runs much colder and the exhaust hood is not needed. The engine room is nicely filled with machinery but the engine room is by no means bigger than on similar boats and the engineers have easy eccess to all equipment.

The Urea (the fluid used for aircraft and airfield deicing) based fluid used in the SCR cleaning system is a 32,5 % aqueous solution and available on the market for onroad, offroad, rail and marine diesel engines and called AdBlue. A typical modern diesel engine uses 2 to 8 % of its fuel consumption of Adblue. Means, with some safety factor included 10 % of your fuel tank capacity is taken away by the AdBlue Tanks. With app. 4000 NM Range at 14 Kts left, not really a problem. As my boat has a hybrid propulsion system, the generators are not running during normal cruise.

But and this is the biggest Con, you need cleaner diesel fuel for this setup. The new MTU engines are therefore cleared for the use of very low to non sulfur diesel fuel including EN 590 diesel, blended Bio Diesel and blended GTL Diesel. The typical "dirty" MGO you would get in certain areas of this planet, would kill the exhaust gas cleaning system.

And the back pressure in the exhaust gas system will increase during the soot filter soot buildup before the regeneration cycle starts. Like on conventionell submarines which go a lot on snorkel dive with the propulsion engine running, this has some side effects on the engines cylinder lubrication. Means, for safety purpose and in order to prolong engine life, we have to lower the oil change intervalls (for peace of mind, we just cut them in half). That is exactly what our Navy does with their conventionell Submarines.

The same setup is used on my shadow boat, the converted cargo vessel. The 8.500 Kw MAN medium speed HFO diesel engine was converted for the exclusive use of EN 590 diesel and all HFO components were removed from the vessel. Similar type of exhaust cleaning system with the use of AdBlue. Works perfect like the above.

Due to this setup we only have one type of fuel on board of all boats and tenders including the turbine aircraft living on the shadow. Due to the large amount of tankage on the shadow, we never have problems with the appropiate fuel supply. But without the shadow, the boat could probably not go to all the places we want, as this clean diesel fuel is not available in all areas of interest.

If You want cleaner boating, You have more systems to watch, more planning for obtaining correct fuels, You need better trained engineers and below the bottom line, more $$$$$$.

Now that is great owner/operator post

"... not really sure if that's accurate to describe what the SeaClean system acronym would be ..."

Thanks for the plug, captholli.

The SeaClean system is a continuously regenerating diesel particulate filter or DPF. We use electrical heaters to maintain the exhaust temperature entering the filter at a level high enough to ensure catalytic combustion of black carbon (soot), hydrocarbons, and nitrous oxide across the greatest range of generator loading. The filter captures inorganic components such as lube oil additives and wear metal from cylinder liners and piston rings without altering their composition. The filters do not remove or reduce NOx.

We normally do not use a DOC or diesel oxidation catalyst in front of the filter since exhaust heating facilitates combustion of the organics. However, we have a test/display unit fitted with a fuel fired heater and a DOC for test and demonstrations. EnerYacht and DeAngelo will show it at the upcoming Triton Expo. The DOC was added as an alternative to active exhaust heating. Catalytic combustion in the DOC increases exhaust temperature at the filter inlet and promotes regeneration. This is intended for use on small generators or main engines where adequate electrical power is not available. Our "standard" SeaClean system uses up to 30kW of power maximum when exhaust temperature is low. When the generator is loaded the heater is normally not required and the electrical power automatically ramps down proportional to the incoming exhaust temperature: low temp = high e-power, high temp = low or no e-power to heater.

The fuel burner/heater is not quite ready for prime time but is very close. It uses diesel fuel to heat exhaust as it passes through a small combustor enroute to the filter. We expect to use periodic regeneration to achieve the best result at the lowest cost for added energy.

We are currently prototyping an IMO III compliant SCR (selective catalytic reduction) system for generators as systems for <300kW simply do not exist and those intended for higher outputs are absurdly large and, in my opinion, will just about spell the end of the 50m class boat as we know it today. We have already seen owners rebuilding rather than replacing older generators in order to avoid the regulatory nightmare created by IMO III and the NOx ECAs (emission control areas). The complete system will not be much larger then the existing SeaClean system and will fit within the engine room volume of current designs.

With regard to urea consumption and tankage, it is a problem but should not be a show stopper. At present, the SCR is only required to be used when operating within a NOx ECA.

Certification is a large/expensive hurdle and is probably among the most odious of the regulatory turds floating in the yachting pond. Sulfur oxides (SOx) were dealt with to large extent by reducing fuel sulfur content and by permitting after market technical firms like EnerYacht to design, build, and install exhaust scrubbers or what is called an "aftertreatment" system. The sulfur regulations were written to control what left the stack, not who is allowed to remove the offending emissions. The NOx regulations were written before technology existed to produce an aftertreatment system and have not changed. The yacht market is so small that major engine manufacturers see no benefit in making the investment in time and money required to serve our market. The cost of certifying an aftermarket aftertreatment system is high but as rebuildable engines become more scarce and yacht designers rob more engine room volume from newbuilds, we hope to see the certification barriers lowered.

Hopefully, yacht design will go back to creating the necessary machinery/treatment spaces first, then the appointments next as normal order of design operations.