DaimlerChrysler Targets Three Bin 5 BLUETEC Diesels for US by 2008
07 September 2006
At a presentation of the E320 BLUETEC sedan in Las Vegas, Dr Thomas Weber, head of Development at DaimlerChrysler AG and at the Mercedes Car Group said that the company was targeting three US BLUETEC models in the R-Class, ML-Class and the GL Class as early as 2008 that meet the 50-state Bin 5 emissions standard.
The E320 BLUETEC, which will be introduced to the market on 15 October—timed to coincide with the introduction of low-sulfur diesel fuel in the USA—is not Bin-5 compliant, and goes on sale as a 45-state vehicle. (Earlier post.)
|The progression of various emissions standards. Click to enlarge. The EPA Tier 2 Bin 5 / CA LEV II standards are currently the world’s toughest.|
BLUETEC will also be made available in a passenger car model in Europe beginning in 2008. DaimlerChrysler does not plan to restrict the use of BLUETEC to the Mercedes-Benz brand alone, and has shown a Jeep Grand Cherokee BLUETEC concept car.
BLUETEC is DaimlerChrysler’s modular emissions aftertreatment architecture that provides the potential for 50-state compliance—i.e, meeting EPA Tier 2 Bin 5 emissions levels, which map to California LEV II levels.
Mercedes-Benz has developed BLUETEC in two versions: in the E-Class an oxidation-type catalytic converter and particulate filter are combined with an improved, extremely durable NOx trap system and an additional Selective Catalytic Reduction (SCR) catalytic converter.
The second BLUETEC version is based on a urea-SCR system, and this is the one that will deliver Bin 5 compliance.
Here, AdBlue, a non-toxic aqueous carbamide solution is stored in an extra tank and injected into the exhaust-gas stream. Injecting AdBlue into the exhaust gas releases ammonia (NH3), which causes the reduction of up to 80% of the oxides of nitrogen into nitrogen and water in the downstream SCR catalytic converter. Achieving the high efficiency here requires adding precisely the amount of AdBlue needed for the respective particular engine operating state.
Because only around 0.1 liters of AdBlue is needed on average for every 100 kilometers driven (the equivalent of one to three percent of diesel consumption), its tank can be designed in such a way that it only needs to be refilled during regular maintenance checks.
|The NOx trap-based BLUETEC system for the E-Class.||The AdBlue urea-SCR-based BLUETEC system for the GL-class.|
|Click each diagram to enlarge.|
DaimlerChrysler said that it is currently developing the AdBlue urea-SCR system for series production and will apply it primarily in large vehicles and SUVs. The GL- and ML-class vehicles are SUVs; the R-Class is a tourer (wagon).
Could there be a reasonable way to create ammonia from the nitrogen in the air and the hydrogen in the fuel such that the extra tank of urea is eliminated? One assumes the guys in white coats at Daimler have considered this, and perhaps there's no practical way to do it.
Posted by: Nick | 07 September 2006 at 10:16 AM
I'm curious why they didn't pursue hydrogen injection. Perhaps it didn't offer the same emissions reduction as urea injection (AdBlue)?
Posted by: John | 07 September 2006 at 12:03 PM
Urea it's easier to manage, store and maybe cheaper to produce. I don't have any data, but a hydrogen system would be much larger and difficult to install than a urea system.
In Europe you already have an urea infrastructure to support the truck industry that wants to comply with euro 5.
Posted by: MH | 07 September 2006 at 12:41 PM
“Because only around 0.1 liters of AdBlue is needed on average for every 100 kilometers driven (the equivalent of one to three percent of diesel consumption), its tank can be designed in such a way that it only needs to be refilled during regular maintenance checks. ”
If these numbers are accurate, then that is going to be quite a large tank of AdBlue or the service intervals are going to get shorter on these vehicles. Just when you thought the trips to the dealer were going to be less frequent with a diesel engine. Perhaps my math is wrong, but the typical service interval in the USA is 5000 to 7500 miles (8065 to 12096 KM). That works out to a tank about 2.1 to 3.2 US gallons in size (about 8 to 12 Liters, respectively), with no reserve. I do not know what the size of the engine bay is like on these Mercedes vehicles and the Jeep GC, but that may be tough to fit a tank of this size into a convenient place. I know the engineers are saying it can be done, but I remain cautiously optimistic.
The other curious thing here is that it appears the byproducts of all of this exhaust “scrubbing” are nitrogen and water. While most of us do not think of water as being harmful, the possibility of adding more nitrogen to the environment is not ideal. Here is the Chesapeake Bay watershed of the eastern USA we have enough problem keeping excess nitrogen out of the water. If more automotive manufacturers move to a urea-based system for diesel engines in order to meet NOx regulations and/or bring new vehicles to North America, are we going to create a new environmental problem or augment an already existing one? Don’t get me wrong, I’d love to see more diesel vehicles in the USA, but I’d rather not see a transfer of the environmental problem.
Posted by: airasch | 07 September 2006 at 01:11 PM
Nitrogen is a very inert gas that makes around 70% of our atmosphere. As a comparison CO2 only makes 0.038% of the atmosphere by volume. Each year we burn millions of tons of gasoline sending millions of tons of CO2 to the atmosphere with a much greater impact in the environment.
Assuming you only have to use 0.1 liters of Adblue for each 100Km compared with more than 10 L/100Km of gasoline typical of many vehicle models currently sold in the US, converting to diesel you could save 30% or more of fuel, reducing significantly your carbon footprint while only sending trough the pipe a much smaller amount of nitrogen with a far far smaller impact in the equilibrium of the gases in the atmosphere.
I do not think Adblue will be a major problem, and diesel could be a very good option to reduce significantly the US dependency on foreign oil, starting not in 10/20 years, but tomorrow.
Posted by: MH | 07 September 2006 at 01:48 PM
If someone was picky about scientific matters they would say nitrogen is far from being inert. The only inert elements are the noble gases: helium, neon, argon, krypton, and radon. These elements cannot form molecules which nitrogen does quite frequently and is a key element of all proteins.
Posted by: tom deplume | 07 September 2006 at 02:22 PM
While most of us do not think of water as being harmful, the possibility of adding more nitrogen to the environment is not ideal. Here is the Chesapeake Bay watershed of the eastern USA we have enough problem keeping excess nitrogen out of the water.
This is molecular nitrogen. 1) The atmosphere is over 78% molecular nitrogen. 2) The urea may well be formed industrially from molecular nitrogen. 3) The nitrogen problem in the Chesapeake and other estuaries is reactive nitrogen, various oxides where N is typically in the +5 oxidation state. Molecular nitrogen has N in the 0 oxidation state. Reactive nitrogen is a nutrient, molecular nitrogen is not (unless you're a microbe in a leguminous root nodule).
Could there be a reasonable way to create ammonia from the nitrogen in the air and the hydrogen in the fuel such that the extra tank of urea is eliminated?
That's endothermic and a serious energy loser. Might as well use raw fuel for the reduction.
Posted by: dt | 07 September 2006 at 03:51 PM
Hydrogen in its pure form turns out to be impractical, unmanagable, dangerous, and incompartible with current technology and systems. The hydrogen molecule is the smallest known and has a tendency to permitae through barriers - like carbon dioxide oozes out thorough a PET bottle and hence affect the quality of the drink.
Posted by: alannjeru | 08 September 2006 at 08:12 AM