From: Georgi Guninski <guninski@guninski.com> On Sun, Sep 27, 2015 at 05:44:00PM +0000, jim bell wrote:
I noticed that (at least!) one media report portrayed this as making VW's less "green". But from another report, I saw that they had 10% greater gas mileage if they were allowed to cheat. (In other words, less CO2 emissions per mile.) Now, the above quote refers to "huge amounts" of NOx. (nitrogen oxides, probably NO and NO2). The question is, for those people who complain about CO2 being a greenhouse gas, what is the relative undesireability of extra CO2 versus extra NOx. Relative harm, and all that. Which is a concept that people who call themselves "environmentalists" seem to have a great deal of difficulty with. This also raises an idea: I've never heard of this, but what would be wrong with allowing differences in emissions based on location? Putting a GPS in a car is trivial today. Producing less NOx inside a city would make sense; producing less NOx while on a cross-country road-trip less so. Jim Bell
I don't understand chemistry. Generally I do, having a degree in Chemistry. However, automobile emissions is a sub-specialty to which I have never been exposed, except for reading occasional articles on the subject. Mostly you don't need to know chemistry to understand the car-pollution situation, however. CO2 is rather innocuous, except possibly for the issue of being a GHG (greenhouse gas; said to keep in heat to the Earth; "Global Warming" or "Climate Change".) NO and NO2 are poisonous, but are present in normal car exhaust in far smaller proportion than CO2. When automobile engines run, presumably there is a tradeoff: You can set the operating conditions of the car to "low CO2" (higher gas mileage) but at the same time NOx goes up. Or, you can lower NOx, but at the price of "high CO2" (lower gas mileage). Something in this scandal stinks to me. As far as I can see, VW recognized that there was/is a tradeoff between the emission of CO2 and NOx. (Where NOx is used as a shorthand for nitrogen oxide (NO) and nitrogen dioxide (NO2; which when at high concentration dimerizes to N2O4, but this isn't really significant for auto-exhaust issues.) "THE RULES" said they had to reduce NOx to some value, call it "Y". But VW recognized that if it did that, gas mileage would go down a lot, perhaps it is 10%. VW made the choice to cheat, to reduce the emission to "Y" but only when the car recognized that it was undergoing emissions testing.
How did this was unnoticed for about 6? years? Maybe other car manufacturers were aware of it. But they may have been cheating, too, greatly reducing their motivation to report VW.
Especially when the diesel consumption on the road is visibly less than in a test environment? That would have been a major clue. But presumably the testers didn't have any way to know how much diesel fuel was actually being consumed on the road by VW's cars.
As suggested in news, likely competitors reversed engineered the cars to see how VW managed to do this. Quite possibly. But I think the trade-off VW chose might actually be worthwhile. At least when the car is not in a city. Jim Bell