Converted Skeptic on AGW

AFIK, DPFs did not exist before the last decade. I know that engines in Model year 2008 started showing up with them. I know little of the history. What I also know is there is a fairly spirited (wrong headed IMHO) opposition to them, and I believe that Cummins got a pass for a number of years, maybe others as well. Mercedes, maker of lots of diesels world wide has been fairly vocal about the pass others have gotten since thier engines pass current standards.

Icarus

 

I was being a little socratic with you. They didn't put dpf's on diesel until that market had uls fuel, which was IIRC 2007 in the US. CARB seemed to decide that it was fine to retrofit old diesels with new filters. The truckers and truck manufactures don't trust the after market filters, which makes it fairly spirited.

If CARB instead just wanted filters on new trucks, or grandfathered old trucks for a period of time, it would not have been as spirited. Part of the politics that added to this was the lead author of the CARB study that justified making a lot of trucks worthless had lied about where he got his phd, which turned out to be a mail order place where you just paid for it. The head of carb, new about it before the vote, but kept it secret. That is when the fireworks happened. Diesel is unhealty, and we need to set PM limits. We have the technology. But don't justify a very draconian law with fraudulent research. If you are a independent trucker that is about to lose his business, based on what looks like made up stuff from a guy that lied about his credentials. And that guy still has his job. You are going to get pretty spirited too. When the real health problems come out in research you are going to tend to dismiss them.

Since you mentioned cummins, here is there dpf on their smaller off highway diesels
Cummins Engines - Tier 4 Off-Highway - Tier 4 Information - Cummins Particulate Filter
IIRC they got an extension to meet NOx, not PM standards. Standards are different between light, medium, and heavy duty trucks. Its only 2012. Companies have only had 5 years in the US, and our fuel is different.

 

Actully, unlike Cat converters, DPFs are not required equipment on new diesel engines. What is required is that they meet emission standards. It just so happens that DPFs are the only current technology, (that and with urea injection) that will allow these engines to meet the standard.

Icarus

 

Muller misrepresenting himself as being a skeptic is just plain bizarre.

 

Actually, scr (and also NOx storage catalysts which are used on the VW Jetta TDI) converts oxides of nitrogen (NOx = NO + NO2) into mostly elemental nitrogen (N2) and water. Nitrogen dioxide (NO2) is actually the most harmful component of NOx, both in terms of "smog-forming" potential and also direct health effects.

 

I thought cats were only required by law in carb states. The other ones just require emissions, not implementation. SCR and DPF are simply the least expensive way to meet emissions standards.

The least expensive technology does have a big effect on regulation though. Cats required the removal of tetra-ethyl lead as a fuel additive. Then CARB mandated mbte as the only replacement, which is a carcinogens and leaked into ground water from the gas stations. Now EPA requires ethanol as the oxygenate where needed, and other reformulated gasolines are allowed in other areas. The CARB mistake with mbte, is one reason many want a go slow approach. IMHO we moved very very slow when it came to diesels and could have moved much faster. Removing sulfur not only allowed the SCR method but directly reduced particulate emissions, making less expensive dpf possible.

The technology on vehicles goes something like this

Technology developed
Changes at the refiners/blenders to support the new pollution control technology
Changes with the vehicle manufacturers to add the tech to vehilces
Slow replacement in the fleet

When it comes to oxygenates there may be a huge amount of PAC politics. The original requirements were for a real need to reduce pollution in carburated cars. Very few of those exist today. The requirement for ethanol in warm weather summer gas may actually increase pollution. Since oil prices may go very much higher, there is the thought that we may need to add more biofuels, but these don't need to be corn. We can act as brazil and require cars meet emissions with E25, but also E0. We can allow switch grass and natural gas to be substituted more easily for corn by making this a M25 requirement also. That way in summer gas refiners would be free to meet the requirements in the best way, and in winter gas we could sub other sources. Fuels and pollution control equipment need to evolve together. Similarly it would be great if diesels were made that had pollution control for B85.

I don't think anyone can hit the evaporative emissions of Pzev with E85 today, but this may be possible with E25 or M25, but the manufacturers need the fuels available first.

 

Thanks for the clarification... The article I read seemed a bit off in its chemistry knowledge but I didn't know enough to correct it!

 

Sure, just wanted to be clear.

Since the nitrogen in NOx is in its oxidized state, the challenge to reduce the NOx to elemental nitrogen has been in dealing with the excess oxygen in diesel exhaust. In SCR, ammonia (from the urea solution) is used as the reducing agent. Urea-SCR is so effective that it has allowed engine manufacturers to optimize fuel economy (and thus relatively high engine-out NOx) and still meet emission requirements for NOx.