Meeting Diesel Emission Regulations Through SCR: Challenges & Opportunities

Automotive IQ sat down with Michael Fischer of Honda R&D Europe to discuss the current landscape and challenges of SCR technology for reducing emissions in diesel vehicles. Mr. Fischer was the chairman of the 5th International Conference on Selective Catalytic Reduction.

"I think, from a worldwide perspective, the most important item is sulfur
because for such high technology after-treatment systems like LNT or SCR,
we definitely need 10 ppm or less sulfur content as standard."

Automotive IQ: I’m here with Mr. Fischer from Honda. Could you describe your background and what you do at Honda?

Michael Fischer: I’m the section leader for the powertrain technology group within our automobile engineering and research department and I’m technically responsible for the powertrain-related R&D activities in Europe, which means advanced research matters but also testing and verification for actual new vehicles for the European market. Our main areas are exhaust gas after-treatment for diesel and gasoline engines, alternative drivetrains like fuel-cell electric vehicles and hybrid vehicles as well as drivability of automatic transmissions. I’ve been doing that for two years and I started with Honda in 2006 as a research engineer for the diesel after-treatment and after five years became section leader for the powertrain area.


Automotive IQ: I understand that you’re in an exploratory phase at the moment. What have you noticed, in your view, as the most challenging things so far with regard to implementing SCR and with the technology in general?

M.F.: For NOx after-treatment of diesel engines, we basically have two competing technologies with Lean NOx Traps (LNT) and SCR technology. The big question has been for many years, which one is the better technology or which technology should be applied to which vehicle size. . Today it is clear that both technologies will be applied and SCR technology is at least required for some heavier vehicles; for some other vehicles it might be more efficient to use SCR technology from a CO2 point of view. Then, of course, we had a lot of fundamental research in the area of how to optimize such a system. Important working areas are the improvement of the AdBlue distribution to have a uniform catalyst inlet flow as well as the control of AdBlue injection to always have the right amount of Ammonia on the SCR catalyst.


Automotive IQ: OBD control as well?

M.F.: Of course, OBD is another very important item because every emission-related system needs to be monitored. Definitely, an SCR system is very challenging for this because we need to monitor the AdBlue quality, the injection system, the catalyst itself, the sensors involved and so on. All these areas are very challenging, and finally we should definitely not forget the customers. It is crucial to understand that there is no "average customer" - every customer is different. Finally, every customer buying our products needs to be happy with it, so we need to design aftertreatment systems which are convenient for all customers.


Automotive IQ: Something that doesn’t require a re-education of the customer.

M.F.: Exactly. Basically, we should not try to adapt the customer to the car; the car needs to be optimized for the customer.


Automotive IQ: In terms of regulations, do you see any effort to standardize for example, the North American diesel emissions regulations with the European ones currently?

M.F.: Of course, it would be desirable for the automobile makers to have a common emission regulation worldwide because this would reduce our effort for the development and homologation of new vehicles. Nevertheless, it’s very difficult to realize this because the driving behavior and the environmental conditions are very different in the various areas of the world. It would be quite good if some regulations would be similar by having a common drive cycle, similar testing conditions and so on. But because of the big variety of customers worldwide, it is still very difficult to agree on a common emission legislation. However, European emission legislation is increasingly applied to other regions such as India, China and other Asian countries.


Automotive IQ: I recently heard talks about solid ammonia as a possible solution and also different additives that are starting to be used in marine fuels. Do you see any possibility for either of those solutions entering the automotive industry in the near future?

M.F.: Definitely, we know that AdBlue is a good fluid because it’s both available and proven and everybody knows about its advantages and disadvantages. But because there are disadvantages, it’s very good that different companies try to develop better solutions. We know that there are a couple of additives and also systems which have a technical advantage like a better low temperature activity because you do not need to evaporate a liquid, or having a lower freezing point than AdBlue. The big question will be if such new technology or some new fluid has the chance to get in the market beside AdBlue, given that there is some existing infrastructure for AdBlue and many companies are already using AdBlue. At the moment there is a big effort by various OEMs to establish a suitable AdBlue infrastructure for passenger cars because that is definitely required.


Automotive IQ: It’s really interesting that you mention that because at least from a North American perspective, much has been invested in infrastructure for AdBlue. It might be too soon from an investment point of view to switch due to the infrastructure investment. Was there a smaller investment in Europe?

M.F.: I’m not sure if the investment was lower because on the heavy duty side we already have quite a good AdBlue infrastructure in Europe. There are many fuel stations supplying AdBlue at the pumps for heavy duty trucks. At a large number of stations, you can get canisters with AdBlue. So you can get AdBlue without any big problems. Finally we will see if there is room for some alternative or maybe just some additive to improve the AdBlue quality or its properties.


Automotive IQ: My last question is, if you had the opportunity to regulate or improve fuel quality through your own legislation, what elements would you put in?

M.F.: I think, from a worldwide perspective, the most important item is sulfur because for such high technology after-treatment systems like LNT or SCR, we definitely need 10 ppm or less sulfur content as standard. The second item is about bio-fuels. In general with bio-fuels, not only diesel but also gasoline, we see a very big problem that each country in Europe has its own introduction plans for different biofuel grades and it is very difficult for the engine and vehicle manufacturers to guarantee the compatibility. What we would like to see is a common direction with a clear pathway for bio-fuels, at least in Europe as a first step.


Automotive IQ: That would probably make writing ECU programs a lot easier and a lot more standardized.

M.F.: Yes, and it would avoid problems in specific countries because of very specific fuel qualities, very specific ingredients or something like this.


Automotive IQ: I really appreciate your insight in to this. Thank you very much.