• CWA 17379 and the Future of On-Road Emissions Testing: An Interview with Nick Molden 

Air Monitoring

CWA 17379 and the Future of On-Road Emissions Testing: An Interview with Nick Molden 

Mar 11 2022

Nick Molden is the founder and CEO of Emissions Analytics, which specialises in the measurement of emissions and fuel efficiency for passenger and commercial vehicles, as well as non-road mobile machinery. Molden has been a persistent advocate for independent emissions testing, has helped to develop standards and with his co-founder, Massimo Fedeli, established Allow Independent Road-testing, or AIR, a non-profit which produces an online emissions index, the AIR Index, that enables consumers, fleet managers and policy makers to make more informed choices about the vehicles they use every day.  

Our reporter sat down with Nick to talk about the creation of the CWA 17379 standard, the state of on-road emissions and the value of portable emission monitors. 

Throughout 2018, you chaired CEN Workshop 90, the workshop responsible for the CWA 17379 standard; can you tell us a little bit about why the workshop was set up? 

It all originated, as so many things in this area, from “Dieselgate.” So, the problem was that real-world nitrogen oxide emissions from – typically diesel – vehicles were many times the regulated limit in practice – four or five times. And the question is: what to do about it from a policy point of view?  

It really showed up the shortcomings of the then-official test cycle which was a short, very gentle twenty-minute chassis dynamometer test, called the New European Driving Cycle, which significantly underestimated what NOx emissions were. 

The regulators came up with this new system called Real Driving Emissions, where you also had to test your vehicle on the road. However, this only applied to new vehicles from about 2017, but the problem was with vehicles from at least back to 2009. So, there was a big section of vehicles for about 8 years that had very high diesel emissions, but no test to label them with their real NOx emissions. And there was no political plan to effectively back-date Real Driving Emissions to fill in the gap. It created a problem for cities, particularly, and other policy makers as to what to do with all these vehicles which, on the surface of it, officially, have very low NOx emissions – 180 mg for EU5, 80 mg for EU6 – but they’re, in reality, 400-, 500-, 600 mg: what do you do with those?  

CEN Workshop 90 set about creating a method with a legal underpinning that would allow the labelling of these pre-RDE vehicles with their real NOx emissions. And opening the door, then, to cities to say, “Right, if your real-world emissions are above this level, then you can’t come in, or you have to pay.” In short, I guess, you’d describe it as plugging a gap for this generation of vehicles where the regulation had failed in order to give some useful information to policymakers. 

As part of the workshop, you spoke to experts from a range of fields, including consumer groups, NGOs, engineers and policymakers: can you give us a sense of their concerns around the emission of nitrogen oxides in urban areas? 

The research comes, generally, to a number of 40,000 premature deaths in the UK every year, due to human exposure to nitrogen oxides. That puts it not as the biggest health risk, but definitely, a significant one, and one that could be quite clearly linked to diesel on-road vehicles. And that collides with the legal requirement for governments around Europe to bring down NOx to below a certain limit. The situation was that central governments were, effectively, breaking the law but then, were passing the responsibility down to cities to solve the problem, but without giving them any tools. So, the aim was to give cities tools so they could actually deliver on their promises to central government, so they could turn their genuine health concerns for their populations and residents of cities into practical actions. 

But I would say, also, that there was a wider interest from industry and cities in future power trains. We’re now very much going down a road of battery electric vehicles, but that’s still not certain and it’s still controversial – and one of the huge ironies of Dieselgate is now the latest diesel vehicles have such clean tailpipes. You know, almost the only thing coming out of them is carbon dioxide and even then, it’s less carbon dioxide than the equivalent petrol vehicle. It’s gone from the sublime to the ridiculous where pre-Dieselgate, diesels were five times the limit for NOx and now, they’re five times below the limit.  

So, if we weren’t in a political world, logically, you’d be expanding the diesel powertrain and hybridising the diesel powertrain as part of our carbon reduction. But that’s, I guess, seen as a little bit too hot to handle – but that is the truth of it. And it’s still a relevant consideration as we struggle to find the best way to reduce CO2 from transportation at a cost that society can accept. That’s ultimately the problem with battery electric vehicles: they’re very expensive and they require you to adapt your behaviour, you have to charge up and you’re range-limited in some cases.  

There’s a long way to go before we resolve the powertrain mix. And, essentially, what CEN Workshop 90 allows is some real information to judge these powertrains in a reasonable way. Move beyond the politics of Dieselgate and the initial reactions to it, and look in the cold light of day: what do these powertrains actually do? Maybe, some diesel vehicles are not as bad as all that and maybe some gasoline powertrains are worse than we think. 

And that fits really within my passion and what we do at Emissions Analytics, which is just try and find out what the reality of it is, so people can make the right choices.  

So, as I mentioned earlier, the workshop led to CWA 17379: tell us a little about this standard. 

Essentially, it is the product of the workshop. The nature of CEN workshops is that groups can get together who have a collective interest to create these standardised methodologies. We worked on it for just under 18 months and we had a group of around 30 experts from cities – quite a lot of manufacturers and consumer groups, as you mentioned, as well. The product of it is a codified methodology, which had been scrutinised and reviewed by this group until we were happy, and then, the CWA17379 codified method is open for anyone to use around the world – it is beginning to be picked up as a useful method for these pre-RDE vehicles. It has a lifespan of 6 years from when it was published, and it can continually be improved during the process as well.  

You know, it’s one of those things where I’ve been keen to help bring the expertise that we’ve developed internally [at Emissions Analytics] over the ten years we’ve been operating and make some of those available for the wider world to use for the benefit of society. It was the product of a lot of work and input from a lot of people and hopefully, it will play some small part in improving urban air quality and good environmental outcomes. 

Now, lots of your research into vehicle emissions has been conducted with portable emissions monitors: why have these systems been so important for your work?  

Well, because it allows you to get straight to what is happening. There are many advantages of laboratory testing because of the control you can have over it, keeping many variables constant, particularly ambient variables like temperature, weather, and so on. That’s absolutely vital, if you’re looking for real fine-tuning, if you’re trying to get half-a-percent improvement here and there – you can only really do that on the dynamometer in the laboratory. But if you’re actually looking for what does that specific car do in real-world operation, and is it within the limit, or is it double the limit, or is it five times the limit, then portable systems are fantastic for doing that, because it’s driven on real roads by real people, warts and all, with rain, potholes, corners, stop-start traffic – all those sorts of things. So, that tells you what really happens. 

It so happens, actually, that portable emissions measurement kit is now really very accurate, as well. It’s not as though they are very crude, hand-held analysers – not at all. They are really like a laboratory emissions measurement system packaged up in a box that can fit in a typical car. But the sample conditioning, the calibration of this equipment is very precise, and now very specified within regulation. There’s been a very recent CEN standard around the accuracy of PEMS equipment which will further improve standards – and actually, the measurement accuracy is really good, within 2-3%, typically. Where you get the variability is in the ambient conditions, and PEMS is great when you can go and test the vehicle in a cold climate, in a hot climate, up a mountain, down a valley, very flexibly because you can just drive it there, in a way that you’re not able to recreate in a laboratory.  

One of the latest pieces of research with which you’ve been involved was conducted by your non-profit, Allow Independent Road-testing, in collaboration with MoneySuperMarket and investigated the emission of carbon dioxide and nitrogen oxides by cars across the UK. The study compared MoneySuperMarket’s data on insurance inquiries with the AIR Index. Surprisingly, just over a third of insured cars in the UK received the Index’s two lowest scores for the emission of nitrogen oxides: could you tell us a little bit about how the Index acquires and compiles its data? 

We take the CEN standard method, the CWA17379, that’s the basis of it, then we use the PEMS equipment to do on-road testing. Very importantly here the cars that are tested are acquired independently, they’re not sought directly from the manufacturers, we will go rent them or buy them in the marketplace. And to get a fully compliant rating on the AIR index, it requires actually a matched pair of vehicles, as well. So that helps guard against if you happen to buy one lemon by accident, you wouldn’t get an agreement between the matched pairs, so that helps us get a very strong handle on the reproducibility of the results.    

So, you get two cars, you go and drive it multiple times, according to CWA17379, and then, effectively, you average the results, look at the distribution of the results, and decide which classification category you can put it into. The AIR Index gives a rating from A at the cleanest end to E at the dirtiest end. On the NOx scale, A lines up with 80mg/km, which is the equivalent of what a EU6 diesel vehicle should achieve, so A is very good, obviously, and E is for vehicles which are above 600mg/km - now, that obviously is multiple times over the regulated limit and common-sensically, you really shouldn’t have any cars in that category but that is the Dieselgate problem that you do in practice. And some of the results are surprising - I mean you mentioned the MoneySuperMarket results. On the NOx scale, there are some very high-selling vehicles from mainstream manufacturers which would be in the E category. Equally, you’ll find some perhaps surprising vehicles in the A-category – there are some Volkswagen diesel vehicles in the A-category, for example. 

So, it goes to show you that, I guess, the received wisdom, if you like, the assumptions that people have taken from Dieselgate that basically all diesel vehicles are terrible, is not true. There are some that are really good, and some that are really bad.  

On the CO2 scale, and that’s really important at the moment, what’s happened after Dieselgate is there’s been a huge shift, people are not buying diesels as much anymore and most people who’ve left diesel have gone back to petrol, its actually only a relatively small proportion who’ve gone to battery electric or hybrids. The vast majority have gone to petrol vehicles. And the problem with petrol vehicles is that they typically have, like for like, about 15% more CO2 emissions than diesels.  

So, I suspect the ones in the higher categories you’ve seen will be high selling petrol vehicles, maybe SUVs because SUVs are now so popular. If you’ve got quite a big petrol SUV that is likely to be quite high on CO2 emissions. So, there’s a lot of paradoxes here, a modern gasoline might be worse than a slightly older diesel vehicle. And that’s really what we’re trying to bring out with the AIR index, to give people the facts so they can make the right decision. 

Finally, the study that we discussed earlier reports that 66% of drivers are concerned about the environmental impact of their vehicles and that, on average, drivers would be willing to pay over £2,000 more for vehicles with lower emissions. So, are you optimistic about the future of green transportation? And what role will on-road emissions testing play in it, do you think? 

We’re at a really interesting juncture, because to solve on-road emissions there’s two priorities in my view, in simple terms. Firstly, it’s to get the old dirty vehicles off the road as soon as possible, if you’ve got a ten-year-old diesel vehicle, that’s bucketing out NOx, there’s nothing you can really do about it except pension it off as quickly as possible. And that’s actually a good thing for the industry, in the sense of turning over the vehicle carpark as quickly as possible.  

The second priority is, then, to look very carefully at where the remaining emissions are coming from – and it would be false to think that it is all coming from the tailpipe. Specifically, what we need to look at are other sources of emissions, particularly non-exhaust sources – like tyres. I think tyres are going to be a big future source of emissions. Not so much that it goes to the air, but, actually, it goes into the water and onto the soil. Tyres are largely made up of the same things that liquid fuel is made up of, they’re largely hydrocarbon-derived, so they contain a lot of noxious chemicals. And a typical car will shed 1 kg of “rubber” every year into the environment. When you multiply that across the billions of cars in the world, that is a lot of organic material being shed into the environment that we’re not really regulating, not managing and it has, at the moment, not well-understood impacts on the food chain. So, that I think needs to be a significant priority. 

Now, where this poses a dilemma is that the heavier the vehicle, the greater the tyre-wear emissions, everything else being equal. So, as we move towards bigger and bigger vehicles, bigger and bigger SUVs, particularly, and also battery-electric vehicles which can be up to a half-a-ton just in the battery pack, the risk is that we get a lot more tyre emissions – and a problem that is already quite significant could get much worse.  

What I would implore people to really think about is, think holistically. Just by simplistically moving away from burning fossil fuels in a vehicle to an electric vehicle, that doesn’t solve all the problems in one go. Obviously, you’ve got the question of, you know, how clean is the electricity in the first place, but if you’re creating a lot more tyre-wear, that’s a potential issue, and the construction emissions for BEVs are also quite significant. So, what we might find is that we reduce emissions less than we think by moving to BEVs and actually, maybe, the optimal way forward is to have a much more mixed market. You’ll still have some diesels and petrols, you’ll have a lot of hybrids – that’s a very efficient way of reducing CO2 and reducing emissions – all alongside significant amounts of battery-electric vehicles. That’s how I think we should be thinking about the future; not as a once-in-a-lifetime scramble to shift the whole of the carpark from where we are to battery electric vehicles. We need to be much more cognisant of what the real-world emissions are from all of these and stimulate a mixed market where you choose the right vehicle for your purpose – that I think is the best way forward.  

And Emissions Analytics are doing a lot of work at the moment testing tyres to understand their chemical composition and what’s being shed into the environment because I think it will gradually be understood that actually that tailpipe, that circular thing sticking out from your car, is no longer the main source of pollution. We need to think in a much broader way. 

For daily news and regular notifcations about monitoring standards for air pollution laboratories, stay updated with Envirotech Online.


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