One of the biggest news stories this last fortnight has been the Volkswagen emissions cheating scandal. In a “wildly illegal” strategy spanning many years, Volkswagen deliberately ‘cheated’ on emissions tests of its diesel vehicles, with software which could identify when the car was undergoing a test, and activate emissions controls only during those times. 11 million vehicles were affected, across a number of brands (including Audi and Skoda). The fallout has included the CEO resigning, a 30% drop in share price, and huge cost to the company (they’ve set aside €6.5 billion for starters).

The “emissions” at issue were nitrogen oxides, which are local air pollutants, contributing to smog and respiratory diseases. I don’t think they’re considered greenhouse gas emissions (correct me if I’m wrong) – nitrous oxide certainly is, but it’s not emitted by diesels.

Diesel cars have been popular in Europe (more than 50% of the car fleet in some countries) because they create less greenhouse gas emissions than petrol cars. They use 30% less fuel, but diesel has about 10% more energy, so on the whole they’re 20% more efficient. The downside is that they tend to produce more pollution – nitrous oxides, microscopic solid particles and the like. “Clean diesel” cars supposedly have plenty of hardware and software in place to help reduce their polluting.

These pollutants are supposed to be tightly regulated, since they can have such a big impact on air quality in cities. But that’s not much help if manufacturers figure out ways to beat the system.

And whether or not it’s being done deliberately, many cars from other manufacturers don’t meet the standards when they hit the roads either:

Road tests of more than a dozen popular models from several manufacturers showed that the raw nitrogen oxide emissions from the cars were on average seven times European standards, according to a little-noticed October report from the same outfit that flagged the VW problems.

Indeed, experts said it could very well be that the high levels of real-world emissions reflected in the ICCT report show not that firms are cheating, but only that it’s all too easy to design a car that passes governmental lab tests for emissions. Once outside the lab, those cars fail in real-world conditions.

Nick Molden, chief executive of Emissions Analytics, a British firm, said that in recent years, Europe had put in place two new standards for tailpipe emissions, each one stricter than before.

“But there was no improvement in air quality,” Molden said. “That was the alarm bell. These results suddenly explained why every major European city has an air quality problem.”

The problem, he said, is that the governmental certification test in Europe “is so gentle. It’s 20 minutes in a lab.”

It’s hard to replicate real-world conditions in a lab, and it’s no surprise that when manufacturers know how they’re going to be tested, they design cars that are designed with those tests in mind – with less consideration to what happens on the road.

Plus, the gap between theoretical performance and on-road performance is an issue for greenhouse gases as well. I wrote a post last year based on a Ministry of Transport presentation:

Vehicle fleet and population

“Essentially, vehicles have always tended to use more fuel on the road than they do when they’re being tested. But the performance gap has gotten larger [for Japan and a number of European countries]. Car manufacturers are becoming very adept at designing cars to do well in the tests, but not on the road”.

As an aside, NZ has a much higher proportion of diesels in the fleet than the US, but we’re much lower than Europe. 8.3% of our ‘light passenger vehicles’ (i.e. cars) and 68.4% of ‘light commercial vehicles’ (i.e. goods vans and small trucks) are diesels. Looking at the number of diesel vehicles which have entered our fleet in the last few years, I would have guessed that there are probably thousands of VW-made vehicles in New Zealand which are affected, but the head of Volkswagen New Zealand has said ‘hundreds’ and plans to give more info this week, so he will probably provide a more precise figure.

Update 6/11/2015: There were apparently 5,548 diesel cars in New Zealand fitted with the software, and “other imports of around 150”, whatever that means. Carbon dioxide issues are also being reported on “at least 800,000” cars worldwide, with some of those petrol. It is not yet clear how many New Zealand cars are affected by this.

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      1. And the point, in any case, was that – whether by intentional cheating, or dancing around the letter of the law – pretty much ALL manufacturer’s “clean car” claims are worth much less than in the advertising.

        Bit like our “100% pure” NZ slogan, come to think of it.

    1. Sales (actually “registrations”, the one-off process when a car enters the fleet) by manufacturer available here – they don’t have the 2014 stats for some reason but still a good guide. There have certainly been thousands of VW brands entering the country in the last few years, although those stats don’t separate the petrol from the diesel.

  1. I don’t think emission control was deactivated, just changed. Increasing NOx emissions are a unwanted by-product of higher efficiency combustion (e.g. lean burn). At high temperatures, generally above the stoichiometric flame temperature, NOx emissions increase (so-called “temperature NOx”), and CO decreases. The higher temperature combustion is used to make the heat engine more efficient, reducing CO2 emissions for the same power output, but at the expense of higher NOx emissions.

    This is a barrier that combustion engineers have faced in recent times in regions with severe NOx emission rules, e.g. California. Large combustion systems (e.g. gas fired power plants) use a multitude of emission reducing tech, including ammonia selective catalytic reduction, a version of which is used in VW’s non-offending engines (AdBlue).

    The VW cheat involves making the air/fuel ratio richer in testing mode, decreasing flame temperature, reducing NOx, but also reducing efficiency and increasing CO/CO2 emissions at the same time. The latter is undesirable in normal use, and could easily be measured (fuel consumption). The increase in NOx, less so.

    TLDR: VW increased NOx to decrease CO/CO2 in normal usage, without the additional expense of exhaust gas treatment.

    1. I think the key to the cheating was the engine computer started using more urea in the exhaust to reduce the NOx’s. When the car wasn’t in test mode the level of urea is considerably reduced but the nitrogen oxides are increased well above what the company claimed.

        1. I thought the Passat used adblue. If they dont use urea then how does the engine controller reduce emissions when it recognises a test condition?

          1. Interesting link. But it doesn’t explain what actually happens to reduce NOx. Clearly something that the engine can’t do while you are driving it around, but I wonder how they did it.

          2. They put more fuel in (make the air/fuel mixture richer), which drops the flame temperature, reduces NOx but increases fuel burn and decrease thermal efficiency.

  2. It’s clear that the bogus european ‘clean diesel’ policy is now shown to be the fraud it always was. And the timing is good. EVs are getting ready to take over.

    They need to quit all subsidies and incentives based on this sham. There is nothing clean about diesel.

    1. Of bigger concern for me is still the huge gap in standards between light vehicles/light commercial and heavy commercial. Trucks still get away with huge pollution numbers. Legally.

          1. …and lower for buses, and even lower for the sorts of buses NZ allows operators to import, and way way lower again for the 30 year old clunkers that NZ Bus and others still persist in using.

            At least that will one side effect of the New Bus Network – these old diesel buses will just have to go somewhere else other than Auckland streets, so I guess they’ll turn up on the School bus runs around Pukekohe and surrounds no doubt.

          2. I’ve seen school buses dropping of kids with exhaust smoke that would have failed the marine diesel grey scale test from the 1950’s.

    2. I just don’t see EV’s taking off in Europe without huge subsidies and incentives(like in Norway), lots of renewable energy (like Norway) and more research into batteries or investment in infra. Electric engines just aren’t that great in cold countries because you have to use so much power on heating for half the year and the batteries store power poorly in freezing conditions.

        1. Not all of us have megabucks to throw at an electric car. Look at the huge number of cheap cars on car yards on used car lots around Auckland. They aren’t being pitched at your average new car/Jag buyer. Even when the Tesla 3 gets here, it’s unlikely be priced as competitively as the US ones will be, even though it’s going to be relatively cheap even before their subsidies.

          The most effective way to reduce vehicle emissions to have a PT system that can take most of them off the road.

        1. To be fair to Auckland Transport, Transdev and KiwiRail, their overhead power lines have fallen down fewer times during revenue service than my car has had a flat battery when I needed to drive somewhere 🙂

          1. I love the Clarke and Dawe sketches. There is a really funny interview (unintentionally) of Steven Joyce just after the Rena went aground where he looks and sounds just the same.

  3. It is possible given the admissions by VW and the fact that other manufacturers have struggled too that the standards may in fact be too high and simply unattainable. However it isnt the end of the world. As standards have been changing over time the European air has become much cleaner.

    1. If reaching standards is at the edge of technology then they are perfect. Regulation drives innovation for the betterment of society.

    2. No it hasn’t got any better. Quote from the original post:

      “Nick Molden, chief executive of Emissions Analytics, a British firm, said that in recent years, Europe had put in place two new standards for tailpipe emissions, each one stricter than before.

      “But there was no improvement in air quality,” Molden said. “That was the alarm bell. These results suddenly explained why every major European city has an air quality problem.”

      So, no improvement in air quality was seen despite the new and stricter standards. That was what tipped the experts off there was a big, dirty, stinking, dead rat somewhere – the air quality wasn’t, you know, actually getting better.

  4. My understanding of diesel was always that it requires more – and more frequent – maintenance for a diesel engine to run well and run cleaner. The number of 5,000km comes to mind (from past ownership of a diesel 4×4 and a diesel ute) But this responsibility rests with the diesel vehicle operator, who almost certainly is used to operating a petrol vehicle that does not require such frequent maintenance… the needed maintenance (Often? Too often?) isn’t done. For this reason, I always considered the idea of “clean diesel” to be a polite fiction in actuality.

  5. Those tests have a ruse for a long time. You have to add about 20% to the advertised fuel usage to estimate the actual usage on the road.

    One country with a big problem is Belgium.

    In Belgium, when buying a car, (at least until a few years ago) you used to get a tax refund if your car emitted less than a certain amount of of CO₂ per km. A small car with a petrol engine will usually fall above that threshold, but with a diesel engine it will usually be below. As a consequence when purchasing a small car a diesel was cheaper than a petrol. Plus a diesel uses less litre / 100 km than a petrol, plus a litre of petrol at the pump is more expensive than a litre of diesel. Plus the government was going to change the registration tax on cars according to CO₂ emissions. So even if you drive only 5000 km per year, a diesel will work out significantly cheaper than a petrol, even if you account for more maintenance cost.

    And now when it’s this calm sunny weather, we have all this air pollution by fine particles from diesel engines around our cities. Oops.

  6. Post updated with new information – apparently 5,500 diesel cars in NZ were fitted with the emissions-cheating software, and there’s a new addition to the saga, with “further unexplained inconsistencies in carbon dioxide emissions readings in some of its cars with the company later confirming at least 800,000 vehicles [gobally] had excessive carbon dioxide emissions – 98,000 of which had petrol engines”

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