Thread: VW caught by the Yanks for breaking emission laws

Originally Posted by Eevo

interesting but useless

Nitric oxide is produced during thunderstorms due to the extreme heat of lightning,[5] and is caused by the splitting of nitrogen molecules. This can result in the production of acid rain, if nitric oxide forms compounds with the water molecules in precipitation.

Scientists Ott et al[6] estimated that each flash of lightning on average in the several mid-latitude and subtropical thunderstorms studied turned 7 kilograms (15.4 pounds) of nitrogen into chemically reactive NOx. Ott stated, ?In other words, you could drive a new car across the United States more than 50 times and still produce less than half as much NOx as an average lightning flash.?

It depends if you are interested in environmental or health effects. Vehicles emit NOx at/near ground level. emissions during thunderstorms are emitted across the whole air column and often washed out by the rain falling at the same time.

To put things in perspective, I was speaking to a leading EU air quality modeller the other week. He said that their models can only predict about 1/3 of the NOx in the air in Europe (they use both natural and anthropogenic sources as model inputs). They were forced to use emissions factors which corresponded to vehicle regulations. If they use "real" nox emissions from vehicles as an input to their models they now predict accurately.

Originally Posted by isuzurover

It depends if you are interested in environmental or health effects. Vehicles emit NOx at/near ground level. emissions during thunderstorms are emitted across the whole air column and often washed out by the rain falling at the same time.

To put things in perspective, I was speaking to a leading EU air quality modeller the other week. He said that their models can only predict about 1/3 of the NOx in the air in Europe (they use both natural and anthropogenic sources as model inputs). They were forced to use emissions factors which corresponded to vehicle regulations. If they use "real" nox emissions from vehicles as an input to their models they now predict accurately.

It would be interesting to know just how they know the "real" emissions from vehicles is measured - I suspect it could be best described as an informed guess, seeing that they would vary widely according to conditions, mix of vehicles etc. Which of course begs the question as to whether the "informed" meant a number that gave the right answer and looked reasonable.

However, there is no doubt at all that emissions of all types, are different in "real" motoring from those measured in testing. But the reason that testing is done in closely specified conditions is that the emissions vary so widely according to the conditions, and it is unrealistic to expect that they will ever match test figures at all closely. What VW have done though is to deliberately game this difference. Other manufacturers may have done this as well, but certainly all manufacturers have designed their products to be able to meet the specified tests, knowing that they will not give the same figures in normal use.

No different from racing yacht designers designing to meet the rules, and doing their best to produce a product better than the opposition even though they were designed to meet the same rules - that are there to try and make the handicap commensurate with the actual speed of the yacht.

And then there is the unanswered question as to how many localities really have health problems from NOx emissions from diesel cars. Certainly in this country there would, I suspect, be far more emitted by diesel trucks, and I doubt there are many localities where it is a problem regardless. And what proportion of diesel cars do these model VW represent in this country anyway?

John

Originally Posted by JDNSW

It would be interesting to know just how they know the "real" emissions from vehicles is measured - I suspect it could be best described as an informed guess, seeing that they would vary widely according to conditions, mix of vehicles etc. Which of course begs the question as to whether the "informed" meant a number that gave the right answer and looked reasonable.
...

There are extensive studies on this in the EU. [Basically they have portable equipment which fits in the back of (any) car and connects to the exhaust] They have measured the emission rates from a huge range of vehicles under a very wide range of conditions. There have been studies for around 5 years showing real emissions were up to 300x higher than test emissions, but a lot of this was put down to the EU drive cycle acceleration rate being unrealistically slow.

Originally Posted by p38arover

Umm, I think Ben might just be that with his doctorate and the research he does.....

Funnily enough the first journal paper I ever published was on NOx emissions from petroleum refineries.
I was also down at the farm when the VW story first broke, and had just heard about 5s on the radio about it before all the media started calling me up.

Originally Posted by isuzurover

Funnily enough the first journal paper I ever published was on NOx emissions from petroleum refineries.
I was also down at the farm when the VW story first broke, and had just heard about 5s on the radio about it before all the media started calling me up.

So what does the AdBlue do?

Originally Posted by joel0407

So what does the AdBlue do?

Ya could do a google search, ya know.


https://en.wikipedia.org/wiki/Diesel_exhaust_fluid

It reduces the nitrogen oxides back to nitrogen and water with some CO2 produced..

Originally Posted by joel0407

So what does the AdBlue do?

The process is called selective catalytic reduction (SCR). NO is reduced to N2 through reaction with aqueous ammonia on a catalyst.

Currently in a DSITI / BCC seminar. Data they have shows 63% of NOx in greater brisbane region is from motor vehicles.