Why you should be interested in tyres

A surprisingly compelling subject

Dinner table, or social media, conversation may centre on arguments over which football team deserves to win the league, or whether the Mustang or Camaro is better, but the common feature of such polemics is that they represent simple and interesting questions.  The topic of tyres, however, and if you dare raise it, may stun your companions into silence.  Tyres are not simple and interesting.  They are complex and boring – at least on the outside.  Delve a little deeper, and they become items of sophistication and almost wonder.  Mysterious, near-anonymous products that power many parts of the modern economy and society.  Omnipresent, but no ingredients label.  Emissions Analytics thinks you should be interested in tyres, and you should talk about them at dinner tonight.

But if you can’t face that quite yet, you should first of all attend our newly launched conferences in Europe and US on tyre emissions and sustainability.  Many excellent events already exist in this sector, but the common factor is that they look at tyres from the inside out: from the industry perspective in how to make better tyres.  Environmental concerns are now forcing us to look from the outside in: how can we mitigate the effects of tyres from their manufacture and usage.  Regulation is coming – and has already arrived in California.

The tyre industry is highly sophisticated yet somewhat secretive.  Challenging problems are solved quietly without disclosing the nature of the solution.  European tyres have achieved combinations of grip, noise and rolling resistance to meet the requirements and demands and of the market, while US tyres have remained simpler in formulation as durability has remained the over-riding preference.  Unlike vehicle manufacturers, which exist in spotlight of regulation and consumer interest, tyre manufacturers just get on with it.  Witness the invention of synthetic rubber in the Second World War, which has defined the industry ever since.

The big challenges today are often environmental.  How to makes tyres with more sustainable materials – however they be defined?  How to reduce microplastic and volatile organic emissions in use?  This is not a problem created by heavy battery electric vehicles, but the near elimination of tailpipe pollutant emissions from modern vehicles has brought it into focus – many vehicles now emit 90% below emissions standards for nitrogen oxides, carbon monoxide, and particles.  Although distance-specific tyre mass emissions may be in long-term, like-for-like decline, this is increasingly offset by more vehicles on the road, more miles driven, heavier vehicles and more torque.  Our testing suggests 26% tyre wear emissions from pure battery vehicles compared to equivalent full hybrids.

To counter this trend, new tyre formulations are being quietly brought to market to handle this heavier and ever more demanding vehicles.  The immediate concern that ‘eco’ tyres could deliver such performance at the price of being more environmentally toxic appears to not to be simplistically true from Emissions Analytics’ latest testing.  On our toxicity potential metric, these eco tyres may in fact be a quarter or more less toxic than standard tyres.  This could to a great extent neutralise the increased mass wear rates, but with two caveats, First, it requires detailed analytical testing to verify this.  Second, these eco tyres come at a financial price to the consumer.

While the focus in such matters of regulation tend to start with new products, it may be regulations about replacement tyres that will have a greater bearing on the combined environmental of tyres.  A brand-new battery vehicle equipped with the latest, most sophisticated eco tyres limit emissions, only for that good work to be undone when they are ultimately replaced by cheaper, less sophisticated alternatives.  A private saving for the vehicle owner may create a public cost in pollution.

Seeking to address these questions, our first event will take place in Prague on 28-29 February 2024, and further details can be found here.  Two months later, on 24-25 April, we will pick up the discussion in Southern California, details here.  We encourage you all to apply to attend and submit abstracts for presentations.

Alongside this, we will be publishing regular, detailed results of Emissions Analytics’ tyre wear and chemical composition testing, along with our monthly newsletter, via our Emissions Intelligence subscription – please contact us to find out more.

Together, these new initiatives from Emissions Analytics are engaging with society and industry to bring about an understanding and appreciation of the sheer cleverness and importance of tyres, and how vital the right choices are for the environment.  Consumers want to do the right thing, but the choice of tyres for many is currently too boring and complex.  Let’s change this.  Let's start the conversation.

Webinar: Tyre emissions from the latest electric vehicles

Our CEO & Founder, Nick Molden presented a webinar on the tyre emissions from the latest electric vehicles on 19th September 2023.

To watch the webinar and download the presentation please see below.

The world is on a path to electrifying everything that moves, primarily driven by the desire to decarbonise. But no vehicle is zero emission, and the latest emissions regulations in Europe, the US and beyond are now starting to incorporate non-exhaust emissions. The task is a major one, though, as changes in other regulations and tastes are leading to ever-heavier vehicles, which is likely to increase tyre emissions. What is less well understood is the chemical formulations used in specialist 'EV tyres', and whether they are potentially more or less toxic that standard tyres. This webinar will share the latest chemical profiling results from our EQUA test programme, to show the key trends.

This is particularly relevant in the light of the California Environmental Protection Agency’s new rule on chemical composition, aiming to reduce the use of the toxic 6PPD preservative. We will show the extent to which alternatives are already being used. We will also consider the progress the European Union is making on its Euro 7 regulation for tyres. Current proposals for a measurement method fromt he Task Force on Tyre Abrasion will be reviewed in the light of our real-world wear rate testing. How efficient and effective will the proposed method be, and what might an optimal initial limit value look like? This testing fits within Emissions Analytics’ expanded EQUA test programme, which includes regulated and unregulated tailpipe emissions and vehicle interior air quality. Watch out for future webinars on these topic, and do subscribe to Emissions Analytics' newsletter to find out about priority access.

FUD off

Fear, uncertainty and doubt in an age of decarbonisation

Fear. Uncertainty. Doubt.  This rhetorical triptych is increasingly used as an insult to describe interventions from anyone who deviates from the current environmental orthodoxy.  When French philosopher René Descartes sat down in the seventeenth century Netherlands to write his Discourse on Method, he also faced FUD.  Fear that his beliefs about the world, both factual and ethical, were built on flimsy foundations. This led to great uncertainty in a time of religious adherence.  The solution was doubt: to chip away at any beliefs that were not based on good reason, applying persistent and critical doubt.  In doing so, he believed that he had rebuilt knowledge and faith but with firm foundations, based on his cogito ergo sum - I think therefore I am.

Rather than being used as an insult, FUD is what should be applied with urgency to the current debate about climate change and transport decarbonisation.  Now faced with a growing body of information and concerns about a strategy of pure battery electrification being the optimal approach, we should stand back and re-evaluable.  Chip away at the idols.
 
Descartes was a supreme rationalist, and reason is what we need.  We debate tailpipe regulation, clean air zones and air quality largely with facts and figures, and logical arguments.  Move onto climate change – a closely related issue – and calm, rational debate gets suspended in favour of polemics.  This changes the nature of the debate in a way that destroys the debate.  For many, doubt cannot be tolerated.  Fear should used to keep order. 
 
The “climate emergency”, as fearsomely styled, is serious.  It is scientifically highly certain that climate change will have bad effects on humanity, possibly very bad.  However, none of the standard models say that life and our planet will end, yet the challenge is being presented as an emergency, of existential significance.  Of ontological significance.
 
But climate change is something to fear.  There are many uncertainties as to what exactly will happen.  Applying critical doubt is essential to working out the optimal response.  So, let’s embrace FUD.  Better than blind faith.  There will always be strongly opposing views – centrist, European technocracy is an illusion – so rather than demonising the traditional energy sector or the environmental NGOs, let’s hammer it out as humans in the human realm.

One of the other more likely health risks in the garage experiment was from asphyxiation due to high CO2 levels, arising from the engine combustion. The parallel in the vehicle cabin is elevated CO2 due to respiration of the occupants. Human harm tends to occur when concentrations exceed 15,000 ppm, although cognitive impairment can occur well below that, which might lead to reduced reaction times and increased accident risk. While the garage concentration reached 8,509 ppm after half an hour, concentrations inside the vehicle when tested on the road reached just 1,564 ppm after the same time, even with the ventilation system on the ‘recirculation’ mode. On fresh air mode, concentrations rose by an average of just 13% above the 417 ppm background. As with PN concentrations, there were big variations between vehicle models as to how fresh the air was kept on recirculation: CO2 increased by 103% in the best case and 275% in the worst.

Overall, therefore, the particle exposure inside the cabin is a bigger risk than when locked in a garage with an idling ICE vehicle of the current generation. While CO2 concentrations in the garage were higher than in the cabin, driving a vehicle is operating a complex, mobile machine and, therefore, even a modestly elevated level of CO2 could compromise safety. It should be noted that some relevant pollutants have not been studied here. Particle mass was not chosen due to the relatively low levels being emitted from modern tailpipes and entering the cabin even with low-quality filters and ventilation systems. Nitrogen dioxide (NO2) emissions are extremely low from gasoline vehicles – the dominant powertrain now – and concentrations in the cabin are also very low. A major area of focus in our future work is the role of volatile organic compounds (VOCs). These tend to be low from tailpipes, although some species can be highly toxic even in low concentrations. Inside the cabin, these VOCs arise mainly from interior materials, especially in hot conditions. Some mix of compounds, of varying potential toxicity, evaporate from seats, carpets, dashboards and other plastics. In short, the greatest risks in the cabin are PN, CO2 and VOCs, while in the garage it is PN, CO2 plus carbon monoxide (CO) for gasoline vehicles and NO2 for diesels.

Taking this complex area and turning into something that vehicle owners and buyers can use practically, the AIR Alliance this month is launching its Cabin AIR Index, based on CWA17934. The most immediate action that can be taken, rather than changing the vehicle itself, is to swap the filter in the ventilation system. Changing the filter regularly is important to avoid degradation, and then the choice of filter brand is important. The initial test results – comparing six different filters on the same vehicle – show that the best filter reduced the interior pollution almost three times more than the worst filter. Therefore, this simple component of typically around $40 in value, can make a significant difference in chronic pollution exposure in the cabin.

For the truth is that there is much common understanding as to our environmental challenges.  There are arguments as to the best solutions, and who should benefit and who should pay the price.  And what is that largely common understanding?  Decarbonisation of transport is vital, and electrification is the key. However, electrification is very different from “full electrification”, and electrification can manifest itself in many ways, including non-battery forms of storage.  The real question is not whether battery electric vehicles will take off, but whether they will reduce total carbon dioxide (CO2) emissions as much as implied.  Air quality continues to improve in most places, and new internal combustion engine vehicles are not the cause, but rather it is from older vehicles and non-tailpipe sources from a wide range of vehicles. Energy efficiency is one important aspect of emissions reduction, but cost efficiency is more important if maintaining our standard of living is the priority.  ‘Net zero’ is nothing magical or sacrosanct.  If we can get to net-minus-80% for half the cost, might that not be better for society in the round? 

Or perhaps: cogito ergo sum hybrida.

With the profound importance of these matters, Emissions Analytics will be redoubling its efforts to bring independent, real-world data to the debate.  We will chip away persistently to reveal the facts, and to analyse, recognising uncertainties where they exist.  We have for many years supported the work of the not-for-profit AIR Alliance in publishing free-access ratings for real-world nitrogen oxide (NOx) and CO2 emissions.  In July, a rating for vehicle interior air quality was added, showing how drivers can reduce their exposures to ultrafine particles in the cabin.  Early this year, we launched the Tyre Emissions Research Consortium, with the aim of bringing together researchers and interested parties from around the world to foster and accelerate understanding of how emissions from tyres affect air, water and the food we eat. Remarkably, it already has over 800 participants.

We are continuing to expand our in-house EQUA testing programme, which takes vehicles from the marketplace and subjects them to testing for their tailpipe emissions, tyre emissions, and materials off-gassing fumes as part of vehicle interior air quality.  We offer access to the full data as part of our subscription products, but from this autumn we will also launch Emissions Intelligence, which will present a monthly webcast with the very latest results and interpretation in the context of market and regulatory developments.  It will allow any market player to have their finger on the pulse of emerging problems and solutions, and will be free for all existing clients and collaborators.

The first webinar in the series will take place on Tuesday 19 September 2023, and will look at the latest developments in tyre emissions testing and regulation, and sharing highlights from our EQUA testing.  Please sign up on our website.

Finally, in 2024 we will be launching a series of conferences, including a European conference on the decarbonisation and pollutant emissions reduction in the non-road mobile machinery, with a particular focus on renewable fuels.  This is a classic area where electrification is valuable but cannot solve all problems – a multi-pronged approach is necessary.  The programme will be published soon.  Do sign up and attend if you are working in this area.

We invite you all to participate in these efforts.  Please get in touch.

We embrace discussion and creative, fact-based disagreement.  We are technology neutral, open to any approaches that can address global environmental problems while preserving standards of living.  We don’t know all the answers.  But we have a good instinct as to where to look.

Cabin fever

Why vehicle interior air quality is worse than in your garage

In our last newsletter we looked at the unethical challenge set by a high profile academic to see whether you would die if locked inside your garage with an internal combustion engine (ICE) vehicle running. Answer: no if you choose a current model, but probably yes if you choose something else and run it in a single garage.  Don’t take the risk.  But what happens if we invert the question?  How safe is it to be inside the same car driven in the open air?  That may sound like a stupid question, as most of us put ourselves in that position regularly, but how much do we really know about the quality of air inside a vehicle?  Is it very different from standing in a garage with an idling engine?

The challenge of the garage test is that tailpipe emissions are being emitted into a confined space with limited air to dilute it.  The question of air quality inside the vehicle cabin is actually the same: pollution from the ambient air is sucked into the sealed, confined space of the vehicle cabin.  In fact, the interior air volume of the car is substantially less than the volume of the garage.  This problem of pollution build-up, and the potential effect on driver health, has become more marked as the construction quality of vehicles has improved such that there is little air exchange except through the ventilation system.

To evaluate this, Emissions Analytics performed tests for vehicle interior air quality across over one hundred vehicles in Los Angeles in the US, Oxford in the UK, and Stuttgart in Germany.  For each test, the interior air quality was measured in real-time for particle number (PN) and carbon dioxide (CO2) concentrations, simultaneously with testing for the same pollutants immediately outside the vehicle from a second, matched, analyser.  Particle number was chosen as probably the single biggest health threat, and CO2 build-up is a driver safety issue representing the stuffiness of the interior air.

The test protocol was modelled on a new standardised methodology from CEN (Comité Européen de Normalisation or European Committee for Standardisation), published in September 2022.  The CEN Workshop Agreement (CWA) 17934 was the product of Workshop 103, which was initiated and chaired by the AIR Alliance and attracted around 40 industry experts in its development and validation.  

The US results, which were performed on a repeated thirty-minute route around Los Angeles International Airport, saw average external PN concentrations of 22,901 particles per cm3.  For comparison, fresh country air is typically around 2,600 particles per cm3, and the concentration out of a post-2018 diesel exhaust averages just 10,000 per cm3.  Across 97 recent model year light-duty vehicles tested on this route, the average interior PN concentration was 21,419 particles per cm3, so only 6.5% below the ambient. As an average this might suggest that filtration via the vehicle ventilation system is largely ineffective, but this is not true.  The range of results was between 9,388 and 47,977 particles per cm3.  On the Cabin Air Quality Index (CAQI) defined under CWA17934, the values were between 0.31 at the best-performing end, and 2.10 at the worst end.  In other words, the vehicle with the best ventilation system protected its occupants by reducing PN pollution by 69% compared to outside, but the worst vehicle saw double the outside concentrations.  This can be the case due to the accumulation of particles in a well-sealed cabin, and where the interior air is not properly refiltered.  A similar pattern was seen on the European tests in terms of the relative concentrations between the inside and outside, but the outside concentrations in absolute terms were, about double – for example, around Oxford the average concentration was 43,312 particles per cm3.  This may come as a surprise, but might be explained by the higher proportion of diesel vehicles with no or compromised particulate filters in Europe.

Thinking back to the garage thought experiment, over one hour with the idling gasoline vehicle in a single garage, the PN concentration rose from the 2,600 background to just 3,529 particles per cm3.  Therefore, concentration rose by about a third, but remained 84% below the average exposure suffered by the occupant of the vehicle testing on the roads of Los Angeles.  The chart below shows the instantaneous and cumulative concentrations from the road test on a Ford Explorer with average performance, compared to the modelled garage PN build-up.  So, by a large margin, you are exposed to fewer particles in the sealed garage than driving in normal on-road conditions, and this is true due to two main factors.  First, the exhaust filtration on new cars has an efficiency of over 99.9%, so these vehicles are emitting a very small net number of particles, even when the ambient air is relatively clean.  Second, the ambient air for the road test has PN concentrations well above background, which must in turn come from sources other than modern vehicles with exhaust filters – most likely from older vehicles, non-exhaust emissions, industrial sources, farming and home heating.  In other words, these modern vehicles with filtered exhausts are not a significant source of PN pollution, yet the occupants may still suffer the pollution from other proximal sources.

One of the other more likely health risks in the garage experiment was from asphyxiation due to high CO2 levels, arising from the engine combustion. The parallel in the vehicle cabin is elevated CO2 due to respiration of the occupants. Human harm tends to occur when concentrations exceed 15,000 ppm, although cognitive impairment can occur well below that, which might lead to reduced reaction times and increased accident risk. While the garage concentration reached 8,509 ppm after half an hour, concentrations inside the vehicle when tested on the road reached just 1,564 ppm after the same time, even with the ventilation system on the ‘recirculation’ mode. On fresh air mode, concentrations rose by an average of just 13% above the 417 ppm background. As with PN concentrations, there were big variations between vehicle models as to how fresh the air was kept on recirculation: CO2 increased by 103% in the best case and 275% in the worst.

Overall, therefore, the particle exposure inside the cabin is a bigger risk than when locked in a garage with an idling ICE vehicle of the current generation. While CO2 concentrations in the garage were higher than in the cabin, driving a vehicle is operating a complex, mobile machine and, therefore, even a modestly elevated level of CO2 could compromise safety. It should be noted that some relevant pollutants have not been studied here. Particle mass was not chosen due to the relatively low levels being emitted from modern tailpipes and entering the cabin even with low-quality filters and ventilation systems. Nitrogen dioxide (NO2) emissions are extremely low from gasoline vehicles – the dominant powertrain now – and concentrations in the cabin are also very low. A major area of focus in our future work is the role of volatile organic compounds (VOCs). These tend to be low from tailpipes, although some species can be highly toxic even in low concentrations. Inside the cabin, these VOCs arise mainly from interior materials, especially in hot conditions. Some mix of compounds, of varying potential toxicity, evaporate from seats, carpets, dashboards and other plastics. In short, the greatest risks in the cabin are PN, CO2 and VOCs, while in the garage it is PN, CO2 plus carbon monoxide (CO) for gasoline vehicles and NO2 for diesels.

Taking this complex area and turning into something that vehicle owners and buyers can use practically, the AIR Alliance this month is launching its Cabin AIR Index, based on CWA17934. The most immediate action that can be taken, rather than changing the vehicle itself, is to swap the filter in the ventilation system. Changing the filter regularly is important to avoid degradation, and then the choice of filter brand is important. The initial test results – comparing six different filters on the same vehicle – show that the best filter reduced the interior pollution almost three times more than the worst filter. Therefore, this simple component of typically around $40 in value, can make a significant difference in chronic pollution exposure in the cabin.

Of all the vehicles Emissions Analytics has ever tested, the Tesla Model X achieved the best cabin air quality rating, achieving PN concentrations more than 92% below outside levels. Both its bioweapon defence mode and its normal modes achieved excellent protection, thanks to a combination of HEPA (High Efficiency Particulate Air) filters. The downside of this approach is a large physical size (about 1.2 metres wide) and the relatively high replacement cost. The upgrade is around $500 currently. While originally only available on the Models S and X, since late 2021 it was also standard on the Model Y.

In summary, we have shown in previous newsletters that we are thinking about vehicle pollution in the wrong way now. New ICE vehicles emit almost no pollutants from the tailpipe, except CO2. To solve this decarbonisation challenge, we are moving to heavier electric vehicles, and in doing so are creating a tyre emissions problem that dominates anything from the tailpipe, as shown in a previous newsletter. In this newsletter, we have shown that being inside a vehicle can be more hazardous than being outside. In short, apart from replacing older vehicles as soon as possible, we should be concerned with non-exhaust and non-vehicular emissions rather than the tailpipe, focusing particularly on fine particles and VOCs from plastics and tyres. We have a good instinctive grasp of exterior air quality problems, but need to improve our understanding of interior pollution. Tesla is stealing a lead on the competition by acknowledging the issue of cabin air quality, and offering a practical solution today. Let us hope that other manufacturers follow, and the new CWA17934 standard can be used to prove their effectiveness.

NEW international Cabin AIR Index launched

Fleet owners, policy makers and drivers now have access to independent, standardised vehicle ventilation ratings 

• Easy to understand and comparable ratings provide clarity for drivers and car buyers.

• The first independent data set enabling policy makers to protect vehicle occupants.

• The independent Cabin AIR Index rates the ability of each filter and ventilation system to protect vehicle occupants from exterior pollution.

• The A-E colour-coded rating is endorsed by global air quality and vehicle emissions experts.

• Moe information available at www.airindex.com/emissions-ratings/cabin-air-quality-in-cars/   

25 July 2023: Today’s launch of the Cabin AIR Index reveals, for the first time using scientific data, the effectiveness of vehicle ventilation systems and the choice of filters in reducing the exposure of vehicle occupants to harmful pollutants.

Developed from more than five years of independent, international research the new Cabin AIR Index ratings reveal accurately how much pollution enters a vehicle compared to the outside air, when it is used in towns and cities.

Exposure to high levels of pollutants in the air can cause a range of serious health issues including respiratory problems, heart disease, strokes and lung cancer¹.

The air quality inside cars and vans (M1 and N1 categories²) is unregulated, leaving drivers and passengers unaware of the levels of exposure to damaging pollutants. In Europe alone, air pollution is estimated to cause more than 300,000 premature deaths each year³. 

The Cabin AIR Index has been created to inform and empower drivers, passengers, fleet owners and policy makers with the real facts about the protection offered by the ventilation systems and filters in the cars they use and travel in. A simple A-E colour-coded rating, based on a new real-world standard, shows the difference in effectiveness in filtering harmful pollutants.

In 2021 more than 97% of the urban population was exposed to concentrations of fine particulate matter above the health-based guideline level set by the World Health Organization⁴. Drivers and passengers, and in particular professional drivers who are in vehicles for several hours each day are now able to compare vehicles and the filter systems, enabling choice, for the first time based on scientific data.

Today’s launch of the Cabin AIR Index also reveals the significant variation in protection offered by the same vehicle, depending on the type of interior air filter used. When tested on the same car, the combination of ventilation system and one filter was only able to reduce the level of exposure to outside particles for drivers and passengers by 30% during the course of the test, whilst the best performing combination of system and filter achieved 82%.

The Cabin AIR Index ratings show ‘at a glance’ how effective the vehicle ventilation system is, allowing comparison with other vehicles, and other filters installed based on scientifically robust, repeatable, on-road vehicle testing according to the new CWA 17934 methodology.

Massimo Fedeli, Co-founder and Operations Director of the AIR Alliance said: “The health effects of breathing fine particulate matter in urban air are now, sadly, well established and estimated to cause more than 300,000 premature deaths in Europe each year. Drivers and passengers in urban areas may assume that closing windows and using the ventilation system prevents exposure to particulate matter, but that is not necessarily the case.

“Following five years of research, today the AIR Alliance is launching the Cabin AIR Index which rates the ability of the ventilation system to filter the number of particles from outside the vehicle and presents the results in a simple A-E colour coded scale.

“The Cabin AIR Index is the first opportunity for drivers and passengers to see the protection offered by vehicle ventilation systems, and also reveals the difference in performance between different filters fitted to the same vehicle, enabling drivers to make a choice when selecting the filter for their car or van.”

Nick Molden, Co-founder of the AIR Alliance said: “The Cabin AIR Index is based on data collected according to the CWA 17934 methodology, the independent, scientifically robust methodology to collect real drive vehicle interior air quality data. In the absence of any regulations for air quality inside cars and vans, drivers and passengers are unaware of the levels of pollution, and in particular the number of particles which enter the cabin.

“Drivers, and especially professional drivers who are in the vehicle for several hours each day, should be aware that the choice of interior air filter can make a significant difference to the quality of air that they breathe. Our tests show that the same ventilation system fitted with different, but compatible filters, reduced the level of exposure to outside particles for drivers and passengers between 30% and 82%.

“We have worked hard over the last three years with our independent, expert academic and industry group to define standardisation of data collection through the CEN Workshop Agreement 17934. We rate data collected by this method on the Cabin AIR Index providing comparative information between vehicles using fair testing criteria, all conducted on-road in real driving conditions. The same standardised test is applied to each different car type.

“For the first time policy makers and fleet owners have the ability to protect vehicle occupants, using the Cabin AIR Index to define the minimum standards expected to protect occupants.”

The results of the seven filters tested for the AIR Alliance on a 2018 Nissan Qashqai and rated in the Cabin AIR Index are:

*Cabin Air Quality Index (CAQI) as defined in the CWA Workshop Agreement 17934
**the age, make and part number of the interior filter which was pre-installed in the test vehicle was unknown.   

The AIR Alliance has now commissioned a programme of vehicle and filter testing and more results will be added to the Cabin AIR Index periodically.

About the Cabin AIR Index 

Vehicle ventilation systems for cars and vans (M1 and N1 categories2) rated for the Cabin AIR Index are tested according to the CWA 17934 standardised methodology which ensures that the results are independent, repeatable and comparable.

The testing is carried out on a vehicle, sourced independently from vehicle manufacturers, with Pollution In-cabin Emissions Measurement Systems (PIMS) equipment recording the air quality inside and outside the vehicle during on-road driving in towns and cities.

For a result to be considered acceptable for rating in the Cabin AIR Index at least three sperate tests must be conducted on each model, within specific boundary conditions⁵ at an average speed between 30 km/h and 50 km/h, with each test lasting at least 30 minutes.  

Testing is conducted with the ventilation system in ‘fresh air’ mode, the air conditioning turned off, and temperature set to 19°C in either automatic mode, or 50% fan speed if manual, and the vents facing forward and level.

The results of the tests provide the basis to rate the vehicle ventilation systems according to the A-E, colour-coded scale.

Cabin AIR Index ratings

The AIR Index website reports the first tests conducted on a single vehicle with different filters showing Cabin AIR Index ratings A-E. Car buyers and fleet operators should consider carefully the implication for the health of vehicle occupants when selecting the vehicle and choice of filter to minimise the ingress of harmful particles.

Background to the Cabin AIR Index testing process

Emissions Analytics, founded by Nick Molden (Co-founder of the AIR Alliance), was a pioneer in methodologies to test on-road tailpipe emissions using Portable Emissions Measurement Systems (PEMS) equipment. Since 2018 Emissions Analytics has also independently tested the air quality inside vehicles using Pollution In-cabin Emissions Measurement Systems (PIMS) equipment, and the insight gained from more than 100 tests conducted by Emissions Analytics informed the development of the CEN Workshop agreement which led to the CWA 17934 methodology from which the Cabin AIR Index has been created.

For more information see https://www.emissionsanalytics.com/vehicle-interior-air-quality.

¹ World Health Organization https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health

² Vehicle Approval categories https://www.gov.uk/vehicle-approval/individual-vehicle-approval-manuals

³ Air quality impacts in Europe European Environment Agency https://www.eea.europa.eu/publications/air-quality-in-europe-2021

⁴ Europe’s air quality status 2023 https://www.eea.europa.eu/publications/europes-air-quality-status-2023

⁵ More details about CWA 17934 and the boundary conditions are available at the CEN website https://standards.cencenelec.eu/dyn/www/f?p=CEN:110:0::::FSP_PROJECT,FSP_ORG_ID:76650,2654151&cs=1A37B6A2248CB063033111B9F708BAB58

Emissions Analytics and the University of Portsmouth collaborate on the study to investigate impact of toxic tyre chemicals in UK waters

Emissions Analytics is thrilled to be featured in a groundbreaking news article by the University of Portsmouth. The article, titled "Study to Investigate Impact of Toxic Tyre Chemicals in UK Waters," sheds light on a crucial research endeavor that aims to understand the environmental consequences of tyre chemical pollutants.

To learn more about this groundbreaking study and the role of Emissions Analytics, we invite you to read the full article on the University of Portsmouth's website. Click here to access the article and delve into the research that is shaping the future of environmental sustainability.

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@portsmouthuni 

Open letter: Regulating pollutants from tyre emissions

To whom it may concern:

An important and groundbreaking part of the proposed Euro 7 regulation involves setting a limit value for tyre wear emissions. This is particularly important as vehicles continue to become heavier, not least with the growing sales of battery electric vehicles. However, the current proposal covers only the total mass of emissions and, therefore, ignores both ultrafine nanoparticles and chemicals released from the tyres. Without changes, it is likely that tyres will be re-engineered to deliver lower emissions of larger particles but potentially at the cost of the release of more invisible nanoparticles and potentially toxic chemicals.

Therefore, we would call on the European regulators to initiate work as soon as possible on a second phase to Euro 7 tyre emissions that would expand the coverage to both nanoparticles and chemical release in real-world conditions.

Regulating mass, and thereby larger particles, is important particularly for marine pollution, as the over 50% reduction in the population of coho salmon on the west coast of North America shows. This die-off has been conclusively linked by academics to a preservative compound found primarily in tyres. By this very fact, it can be seen that it is not only the particles themselves that is causing the issue, but the chemicals leaching out as those particles settle in the environment. Furthermore, these same tyre chemicals are being seen on a widespread basis in human foodstuffs and excreta.

These chemicals are typically volatile organic compounds. Within this broad collection there is group of aromatic compounds, many of which are carcinogenic, such as polycyclic aromatic hydrocarbons (PAHs). To some extent these are regulated at the tailpipe currently through the total hydrocarbons limit value, although this could also be made more stringent and targeted to the most potentially toxic individual compounds. Eight compounds are also restricted under the REACH chemical regulation, but the coverage is too narrow and the limits too accommodating. Emissions Analytics presented on this topic at the fifth session of the UNECE Task Force on Tyre Abrasion on 30 September 2022¹. There is regulatory precedent from Switzerland, where the 2014 particle number standard (SN 277206:2014) included a secondary emissions test for certain target chemicals—including PAHs and nitro-aromatics—based on the US Clean Air Act section 202².

Nanoparticles are already regulated at the tailpipe since Euro 5. This intervention has been highly successful in reducing in-use emissions by particle filters in most vehicles, and measurement of these ultrafine particles is being expanded into the periodic technical inspection regimes in a number of European countries, which in all likely will deliver further significant reductions in real-world particle emissions. As the evidence for the negative health outcomes from chronic and acute exposure to nanoparticles becomes ever clearer, the value of this regulation grows. Yet, there are no current plans to regulate the same particles from tyres, despite tyres being made of the same underlying fossil materials as liquid fuels. Multiple academic studies have shown that tyres release large numbers of these particles in real-world use. Particle number measurement from tyres has been included for many years in the investigations of the Joint Research Centre of the European Community and the Particle Measurement Programme³, and such efforts should be accelerated to address this growing environmental issue.

In summary, we call on European regulators to apply the same approach they have applied to the tailpipe to the growing issue of tyre emissions. Particle mass, particle number and volatile organic compounds released from tyres must all come within a successful Euro 7 regulation at the earliest opportunity.

Signatories:

Nick Molden, Chief Executive Officer, Emissions Analytics
Dr Andreas Mayer, Chairman of the Scientific Committee, VERT Association

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Footnotes:

1. https://wiki.unece.org/download/attachments/179700528/TA-05-04%20Emissions%20Analytics%20UNECE-EU%20presentation%2030%20September%202022.pdf?api=v2

2. https://www.bafu.admin.ch/dam/bafu/de/dokumente/luft/fachinfo-daten/sn_277206_-_testingofparticlefiltersystemsforinternalcombustione.pdf.download.pdf

3. http://www.combustion-engines.eu/Particle-number-measurements-in-the-European-legislation-and-future-JRC-activities,116158,0,2.html

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Source: Nick Molden | Dr Andreas Mayer

Posted 27 June 2023 on Dieselnet

Don't try this at home!

An emissions thought experiment

Increasingly simplistic calls to #Stopburningstuff and #Stickyourselftothings have recently been accompanied by another call: that anyone who challenges the virtues of battery electric vehicles (BEVs) should shut themselves in their garage alongside their idling internal combustion engine (ICE) vehicle for an hour, to see whether they emerge to tell the tale.  This is a rather unethical, and arguably shocking, call that can only cheapen the decarbonisation debate.  It is one thing coming from fringe on-line influencers, but quite another when it comes from well-known, vocal academics.  

The tastelessness of the proposal aside, as Emissions Analytics is committed to using independent testing to understand real-world emissions questions, we have taken the challenge in the form of a thought experiment.  The conclusions from previous newsletters are that modern ICE vehicles are extremely clean relative to older ones, while BEVs have low but non-zero pollutant and carbon dioxide emissions, leaving the optimal policy more finely balanced than typically thought.  Contradicting this, does the challenge, while flippant, hold an essential truth?

Traditional thinking is that toxic fumes would quickly overwhelm you, while a BEV would sit there passively emitting nothing.  Such an experiment tests in microcosm the effects of vehicles on the wider environment.  To see what the likely effects would be, we can forecast pollutant concentrations in our test laboratory using Emissions Analytics’ real-world test data from tailpipes and non-exhaust sources, together with the latest academic research.  

Without wanting to spoil the result, as with so much in the decarbonisation debate, the answer is nuanced and highly sensitive to the selection of the vehicles.  So, it should be emphasised in the strongest possible terms: don’t actually try this at home!  

A typical single European garage is about three metres wide, six metres long, and three metres high – so, about 54 m3 in volume, which is similar to one of our laboratories.  Let’s assume a constant ambient temperature of around 20 degrees Celsius, which is in line with the temperature used for a vehicle certification test.  Vehicle emissions should be estimated from cold start, with the engine having been soaked at the same temperature overnight.  For the thought experiment, it is assumed that no pollutants escape the laboratory, although some gas egress would be necessary to avoid gradual pressurisation of the space.  To avoid accusations of sophistry, we will assume that the ICE vehicle does not have stop/start or other cut-out system engaged, so it is idling throughout.

The laboratory is assumed to contain air with standard background gas and particle concentrations, as shown in the table below.  Also indicated in the table are guides as to when concentrations of each pollutant start having negative human health or cognitive effects (the ‘threshold of harm’), and the immediate danger levels.  These danger levels have been compiled from multiple sources, many from the world of occupational safety.  For some, there are some wide variations in views, but we have tried to pick a fair midpoint for the purposes of illustration.  The references are listed at the end of the newsletter.

First, let’s first take the controversial one: a diesel.  Diesel is a fuel that burns around a quarter more efficiently than gasoline and was for a generation pushed as a route to decarbonisation, only then to be undermined by excessive real-world NOx emissions.  Many air quality problems we suffer today arise from these excesses.  In this case, we have taken a 2021 Volkswagen Passat 2.0 litre 148 bhp front-wheel drive automatic vehicle certified to the latest, strict Euro 6d-ISC-FCM emissions standard.  The results are modelled by using the second-by-second data from an actual real-world test by Emissions Analytics on its EQUA test route, using a Portable Emissions Measurement System (PEMS) augmented by sampling of VOCs onto thermal desorption tubes for later GCxGC-TOF-MS analysis.

During this hypothetical experiment, the vehicle would suck in and then emit about 30 m3 of gas – mainly nitrogen – which is equivalent to about 55% of the total laboratory air volume.  The colour coding indicates whether the concentration after one hour is below the no-harm level (green), or between the no-harm and immediate danger level (amber).  We have also considered whether the process of combustion would use sufficient oxygen from the air to create an asphyxiation risk.  Clear to see is that there is no red, which would indicate immediate danger. 

The most dangerous pollutant, therefore, is nitrogen dioxide, but the forecast levels are still half of the recommended immediate danger levels, despite the amount of air in the laboratory being relatively small.  Even with this worst-case pollutant, if the volume of the laboratory were just 1,438 m3 (about 27 single garages, or the interior volume of an Airbus A380 aircraft), the amount of air would be sufficient to dilute the NO2 to the point of no harm.  Put this car in the open air, and you can see why this powertrain is no longer a problem from an urban air quality point of view.

The experiment was then extended to a modern gasoline vehicle: a Renault Clio 1.0 litre 88 bhp front-wheel drive manual vehicle certified to the Euro 6d-TEMP-EVAP emissions standard.  The main difference in the outcome is for NO2, which is now at a negligible level, and CO, which is about double the diesel vehicle.  Carbon monoxide is rightly feared as highly poisonous gas to humans, and even modern gasoline vehicles emit a significant amount when the engine is cold, but after about two minutes the catalytic converter brings it down to low levels, even in dynamic driving.  As this engine is smaller than the diesel one, the total amount of gas ingested and then exhaled in one hour is only around 12 m3, or 22% of the total volume of the laboratory.

So, for both ICE vehicles, idling in a single garage for an hour, is likely to be negative for your comfort, health and enjoyment, but not fatal.  But are we covering everything?  If we sit alongside a BEV, are there any effects at all?

As we showed in a previous newsletter, VOCs don’t just come out of the tailpipe, but also ‘off-gas’, or evaporate, from the surface of car tyres, as they are substantially made from components of crude oil.  For the Tesla Model Y tested, we found that total VOCs from the tyres was 0.26 grams over one hour.  If these tyres were the only source of VOCs, they would lead to 1.2 ppm in the laboratory at 20 degrees Celsius.  The distinctive smell experienced when entering a tyre warehouse is caused by these VOCs.

There are two further non-exhaust sources of VOCs.  First, fuel evaporates from the fuel tank of an ICE vehicle, even though most gasoline vehicles have ‘canister’ systems to capture as much as possible.  The US Environmental Protection Agency Tier 2 regulations limited these emissions to 0.05 g/mile (0.03 g/km), and they have been tightened significantly since.  If 60 km were travelled in one hour, this would mean evaporative emissions of 1.8 grams.  

Second, a recent academic paper on unreported VOC emissions from road transport highlighted the issue of VOCs from the evaporation (not usage) of screenwash, which contain a mix of mainly alcohols, and which the authors termed “non-fuel, non-exhaust” emissions.  The paper proposes a distance-specific emissions factor of 58 mg/km.  To convert this to grams per second for the purposes of our experiment, we assume the same average speed of 60 km/hour as above for the test cycle the emissions factor was derived for.  That implies total emissions over one hour of 3.5 grams.

In total, these non-exhaust VOCs add up to between 3.8 and 5.6 grams over the hour.  The lower end of the range is for the BEV, as there would be no fuel evaporative emissions, although this may be offset by larger tyres, which is a trend with battery vehicles due to their weight.  The totals for the exhaust alkanes and aromatics were 0.07 grams for the diesel and 0.11 grams for the gasoline.  Therefore, the non-exhaust sources are around 50 times higher than the exhaust VOCs.  In summary, it is best to not to dwell in a small, sealed space, whether it contains an idling ICE vehicle or a BEV that is switched off.

To this approach there is one important caveat.  Change the car to an older one, and the outcome may not be as favourable.  Older gasoline vehicles can have much higher CO emissions, a gas that can have rapid and terminal effects, while older diesel vehicles are famous for their elevated NOx emissions.  The Volkswagen Passat examined here had NOx emissions of 19 mg/km when tested on Emissions Analytics’ combined EQUA route.  This is 76% below the regulatory limit, which is typical of the current generation of diesels.  Wind back only five years, and the emissions would have been more like 400 mg/km.  Being locked in the garage with that car would lead to a poor health outcome.  This is why, fundamentally, the Ultra Low Emission Zone in London, and similar schemes in other countries, are beneficial to air quality, as it is the older vehicles that are a disproportionate source of pollution.

The conclusion from this analysis, apart from avoiding academics with unethical experiments, is that how we think about vehicle emissions is ripe for a complete overhaul.  Most of the impacts come from the tailpipe of older vehicles, and from non-exhaust sources on new vehicles.  Any properly functioning modern vehicle, operating in the open air, will contribute a negligible amount to air quality problems from the tailpipe.  The carbon dioxide problem remains, however, which is the subject of extensive discussion elsewhere.

It remains true that ICE vehicles produce a range of potentially highly toxic compounds from combustion, but at current concentrations when rapidly diluted in the open air, they cease to be a major problem.  But this insight points to the next major are of concern: inside the vehicle cabin.  Pollutants from older vehicles enter through the ventilation system, and VOCs evaporate from the interior materials, to which the driver and passengers are exposed over extended periods within a sealed cabin.  Without the benefits of dilution and filtration in a poor ventilation system, the health exposures can be significant.  We will look at this in our next newsletter…

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References

Carbon dioxide (CO2): https://www.fsis.usda.gov/sites/default/files/media_file/2020-08/Carbon-Dioxide.pdf
Carbon monoxide (CO): https://www.epa.gov/indoor-air-quality-iaq/carbon-monoxides-impact-indoor-air-quality 
Nitrogen oxides (NO2): https://nj.gov/health/eoh/rtkweb/documents/fs/1376.pdf 
Nitrous oxide (N2O) http://www.ilo.org/dyn/icsc/showcard.display?p_card_id=0067&p_version=2&p_lang=en 
Particle number (PN): Emissions Analytics' testing
Formaldehyde (CH2O): https://www.osha.gov/sites/default/files/publications/formaldehyde-factsheet.pdf 
VOCs: https://getuhoo.com/blog/home/understanding-vocs-and-its-effects-on-health

What matters is not the promise of electric vehicles but the actuality

Friday 18 September 2015 saw Dieselgate break.  This was the culmination of a growing dissonance between real-world nitrogen oxide (NOx) emissions and official values for cars and vans.  The rupture was created by governments picking a technology, for the purposes of decarbonisation, where too much was taken on trust within a fragile governance system.  The industry said, rightly, that technology existed to solve the NOx emissions.  The sad reality was that this technology wasn’t deployed in a way that actually reduced NOx enough in practice, and Europe has been dealing with the air quality consequences ever since.

Equivalent failures must not happen as we try new routes to decarbonisation, especially as a generation has been lost with the diesel experiment.  Many air quality problems have been solved even with internal combustion engine technology, with the simpler challenge remaining of updating the car parc.  But decarbonisation is harder, and that is why the promise of battery electric vehicles (BEVs) – the leading contender in light-duty vehicle CO2 reduction – is rightly being scrutinised in exhaustive detail.

Mr Bean actor and car collector Rowan Atkinson’s recent intervention, saying he felt “duped” by the green claims of BEVs, caused a stir, not least because the article appeared in The Guardian, a well-regarded, environmentally conscious UK newspaper.  Much electronic ink has been spilt since, including a subsequent ‘fact check’ by Simon Evans, a climate journalist, in the same publication.  In the spirit of open enquiry and technology neutrality, and given the importance of the topic, we decided to perform a ‘fact fact check.’  In doing this, Emissions Analytics’ only motive is to get as close to the truth as possible, and to acknowledge where we have uncertainties.

In headline, most of what Simon Evans wrote is true, including:

• BEVs won’t solve all the problems associated with car use.  Our comment: very true, and may in some specific cases make them worse.

• BEVs reduce greenhouse gas emissions by two-thirds on a lifecycle basis relative to combustion engine cars in the UK, and the benefits are growing.  Our comment: performing accurate lifecycle analysis is exceedingly hard, and the answer is sensitive to your choice of model and input assumptions.  The two-thirds claim is in the range of plausible estimates, even though Emissions Analytics’ work put the estimate closer to half currently.  Nevertheless, the point stands.

• Emissions from producing batteries are significant, but are quickly outweighed by the in-use emissions from gasoline and diesel cars.  Our comment: how quickly depends on the true lifecycle emissions of the battery, vehicle and fuel, but it is most likely to be in the two to seven year range in the UK (with a wider range across Europe).  Given that a car typically lasts about 13 years, anywhere in this range could be deemed quick.

• Hydrogen is not a mainstream and proven technology in the same was as BEVs are currently, although it may improve too.  Our comment: we agree – it is predicted to improve, and may emerge as the preferred solution for freight transport where the size of the battery is problematic.

• Battery electric technology is the most energy efficient of the alternatives.  Our comment: true, noting that efficiency is an important but not the only consideration.

• Batteries may well outlast the rest of the vehicle.  Our comment: data on battery longevity is encouraging on the whole.

• Lithium-ion batteries do not contain rare earth elements.  Our comment: batteries often contain scarce materials, and rare earths are used in electric motors.
  

However, there is one sentence in the article that we should focus on in particular.  Not that it is incorrect, but that it is true in a dangerous way:

“Indeed, without a widespread shift to EVs, there is no plausible route to meeting the UK’s legally binding target of net zero greenhouse gas emissions by 2050…”  [To clarify, in context “EVs” meant BEVs, excluding hybrids.]  This sentence is important because it is a fact, but it is a fact by definition.  In other words, legislation defines BEVs as zero emissions.  Bingo!  But are they actually zero emissions?  No, as Simon Evans correctly points out.  The manufacturing and electricity-generation emissions are defined out of the equation.  The manufacturing emissions are mostly parked offshore; in practice most of them occur in China, where battery materials and processed before they can be utilised.

So, we have a rapidly looming echo of Dieselgate.  You cannot define your way to decarbonisation.  Repeating the assertion that BEVs are zero emission doesn’t make it any more true.  BEVs in the UK are lower carbon than any current alternative – that is true.  But they come at a cost and with consequences – economically, geopolitically, environmentally, ethically – that make them no more than a highly promising and valid alternative alongside many others.

Let’s not wake up on Tuesday 18 September 2035 to find that we have applied gargantuan resources, failed to reduce CO2 enough, and created new unpleasant side-effects.  

So, Rowan Atkinson may be right for the wrong reasons, and others wrong for the right reasons.  The truth is that Europe, and the world, perhaps cannot afford another Dieselgate.

AIR welcomes the publication of a standardised method to collect vehicle interior air quality data

Emissions Analytics was pleased to support the AIR Alliance with testing to validate this new standardised method for measuring vehicle interior air quality, so it can help reduce the exposures to pollution for drivers and passengers.

Environmental justice

Why distributional efficiency matters

The term ‘environmental justice’ can often be used in a mushy, socialistic sense, but behind it is a deadly serious concept.  Put broadly, it means that all parts of society should be treated equally under environmental law, or that everyone has the right to the same protection from pollution and other harm from emissions.  More strictly, it can be seen as a form of allocative efficiency.  In other words, environmental interventions should be directed where they create the most benefit, up to the point that the marginal benefit equals the marginal cost of delivery.  Protection from emissions shouldn’t be the preserve of the rich or powerful, but should be judged beneficial for anyone to whom it can deliver a net improvement in the quality of life.  Applying this concept is important in any free society where people are not all living in the same circumstances, with the same preferences and behaviours.  

Through this lens, we can develop an additional perspective on the current debate around the decarbonisation of transport.  In doing so, we can see that a multitude of solutions is the optimal approach not just because of constraints on resources, the actions of hostile states, and the state of our electricity grids, but also because people are diverse, and society’s interests are best served by giving each person the most suitable mode of transport.

Switching from an internal combustion engine (ICE) vehicle to a battery electric vehicle (BEV) is an investment.  As well as the obvious financial investment on the part of the buyer, it is an environmental investment in the sense that higher carbon dioxide (CO2) emissions are generated during manufacture which are then offset during the usage of the vehicle.  As a good guide, the CO2 footprint of BEVs is greater than that of ICE vehicles because of the emissions from making the battery, as the elimination of the engine and other components is roughly offset by the electric motors.  Further, electricity generation according to the average mix in Europe or the US creates about as much CO2 as the oil extraction, refining and distribution.  Therefore, switching to a BEV initially makes CO2 worse, until a ‘break-even’ point is reached after a period.  It should be well noted that these averages are offered as a rule-of-thumb in order to simplify a complex picture and reveal the break-even concept, not to downplay the actual variability and spread in manufacturing emissions, grid mix and so on in specific places.

Estimates of how long into the life of a vehicle the break-even point is reached vary widely, as the result is sensitive to the interaction of the following main factors:

• Carbon intensity of the electricity grid

• Embedded carbon in battery manufacture

• In-use vehicle emissions rates

• Distance driven per year.

Electricity grids vary from near-zero CO2 in France to largely coal in Poland – in the latter scenario most BEVs never pay back the manufacturing CO2.  Embedded carbon in battery manufacturing typically varies between 2.5 and 16 tonnes, which is driven by a combination of mining, refining and transporting the wide range of rocks and minerals required.  In-use emissions from modern gasoline engines average around 184 g/km according to Emissions Analytics’ real-world EQUA testing on European vehicles, but most fall in the range from 107 g/km for the best fully hybridised engines to 248 g/km for non-hybridised sports utility vehicles.  As a result, even assuming average driving distances per year, you can get almost any answer for the CO2 break-even date, depending on your location and the type of the comparator vehicles.  As a guide, most commonly cited break-even points fall between two and eight years.

This analysis, however, neglects the vital element of the distance driven per year, which is often – as above – assumed away as some representative average.  According to Field Dynamics, in 2019 – pre-Covid – the average UK car was driven 7,124 miles (11,470 km).  The UK is around the average of European countries in this respect.  The distribution of annual miles across all cars subjected to periodic technical inspection (PTI) saw the majority of cars with less than 5,000 miles per year (8,050 km) and just 0.5% above 30,000 miles (48,300 km).  This matters because the fewer miles driven, the longer it takes to reach the break-even CO2 point.  The table below compares trading in your old ICE vehicle for a typical BEV, rather than changing to a typical full hybrid electric vehicle (FHEV) emitting 120 g/km.

* Proportion split pro rata from original report.

On the other factors above, typical average values have been taken: average grid carbon intensity for Europe and seven tonnes of embedded carbon in the battery.  Calculations here take the mid-point of the distance ranges, and the top group is assumed to have an annual mileage of 35,000.  The CO2 and break-even calculations assume driving behaviour is the same between the different vehicles.  It is further assumed that vehicles have a twelve-year useful lifespan on average; while many last longer than this, the number of miles driven falls rapidly as they enter a twilight life of reduced use.  We should note that there is a potential bias in these numbers as vehicles are not subject to the PTI test in the UK until three years old.  

These results prove that the more intensively a BEV is used, the quicker it will pay back the CO2 investment.  For the heaviest users, that payback will be within one year, and deliver about ten times the overall CO2 savings than in the original battery manufacture.  At the same time, the lightest users never practically pay back that investment if they switch to a BEV, only offsetting half of the battery emissions.  Therefore, those light users are much better switching to the FHEV.  Most crucial is the proportion of cars that fall into this category: about one third.  If these people take the FHEV option rather than switching to the BEV, the overall reduction in CO2 across the fleet would be 17% greater, and the reduction in the need for scarce battery materials would be around 32%.

This proportion will of course be lower in countries with cleaner grids, where the batteries have been manufactured using cleaner energy and the in-use emissions of the ICE vehicles are higher.  Equally, the proportion will be higher in the opposite circumstances.

Applying a similar calculus to the US, we see that it is generally a much more suitable region for vehicle electrification.  While it shares a similar pattern of grid electricity to Europe – majority based on fossil fuels, with big variations between regions – other factors work to its advantage.  First, US car owners travel around 13,500 miles (21,600 km) per year on average, almost double the European average of about 7,000 miles (11,200 km).  Therefore, a US driver pays back the CO2 invested in a BEV's manufacturer in half the time.  Second, US wholesale energy costs around one quarter of Europe’s, so it can more credibly and competitively build the necessary extraction and processing supply chain, rather than just the final battery assembly part.  Third, North America is the global region with the highest degree of urbanisation, and BEVs offer the biggest efficiency gains in urban driving, due to powertrain efficiency at slow speeds and regenerative braking.

In summary, this analysis can be put as: why are we forcing light car users to spend more money on vehicles that actually pollute the planet more?  While Zero Emission Vehicle (ZEV) mandates may be direction-finders and worthy aspirations, it is also very important we make sure that those who do convert to BEVs are the right people, from an allocative efficiency point of view.  ICE bans are even more problematic than ZEV mandates because ‘success’ would be wilfully suboptimal  A better approach would be to drop the bans and be highly selective with mandates, and rely more on the CO2 targets and/or carbon pricing to set the direction and then let the industry and consumers rearrange their supply and demand accordingly to deliver the best environment outcome in the most efficient, speedy and equitable way.  In this way, lightly used cars would not be swapped for BEVs, saving money and CO2.  That would be true environmental justice.

Champagne Supernova?

A bright light, with a heavy weight

When an exploding star led to the observation of supernova SN 2003fg in 2003, it was nicknamed the ‘Champagne Supernova’ due to its unusual brightness, and its inexplicably great mass.  Many supernovae eventually succumb to their own weight, leaving behind a black hole.  Are we at this stage with battery electric vehicles (BEVs)?  Their prospects are currently shining brightly despite their literal weight as well as their likely wider toll on the environment, from watercourses to the seabed, due to their production.  Hybrids, by contrast, tread relatively lightly on the planet, yet give off a more muted glow of past glory – perhaps more like a red dwarf.  In this newsletter we want to consider a further way in which vehicle size and weight matter, and why the BEV industry must address this rapidly if it is successfully to deliver pollution reduction.

Astronomical parallels aside, we can simply say that BEVs are too big and heavy right now.  Yes, there are heavy internal combustion engine (ICE) vehicles, but on average BEVs are around 40% heavier and 40% bigger like-for-like, as set out in a previous newsletter.  This trend may well continue, and the weight premium increase, as BEVs come increasingly equipped with lithium ion phosphate (LFP) batteries as they are cheaper and require fewer scarce materials.  It may even be the case that this weight leads to structural risks for transportation infrastructure, such as roads and car parks, although this has yet to be proven.

While this is all true, it is easy to get stuck in a pattern of ‘trading averages.’  As Senecal et al meticulously pointed out, you can only assess the decarbonisation potential of BEVs in the US by looking at local-scale grid electricity, and marginal rather than average carbon intensities.  Similarly, with vehicle selection, you can only judge the benefit by understanding the marginal changes.  If someone replaces a frugal gasoline car with a larger BEV, that is likely to be worse for the environment in the round. Equally, switching from a large gasoline V8 to a small city BEV is very likely to be better.  It is easy to make simplistic ‘stop burning stuff’ slogans stick when you conjure up the image of a pre-particle-filter diesel being replaced by a gleaming Tesla.  However, for the same investment, you are likely to get more pollutant and carbon dioxide (CO2) emissions reduction from trading those old diesels up for the latest full hybrid electric vehicles (FHEVs).  So, what we mean by an ICE vehicle, and the variation in performance within that group, matter.  Put another way, it is not the optimal approach to dispense with all ICE technology just because many are high-emitting, just like it would be wrong to reject all BEVs just because many are currently very heavy.

Our previous newsletter suggested that tailpipe emissions from FHEVs had reached a ‘do no harm’ status, by showing levels more than 90% below a range of air pollution legal limits.  What this did not show was whether those apparently low levels were in fact sufficiently de minimis to be of little concern, or whether we were still burning stuff in a detrimental way for air quality.  An immediate caveat to make is that there is a relevant difference between this European test and apparently similar US vehicles.  In Europe, unlike the US, a large and increasing proportion of gasoline ICE vehicles are equipped with particle filters, which significantly reduce the particle mass and number emissions from the tailpipe.  Therefore, US particle emissions remain concerning and, as a result, there is greater benefit in switching to BEVs in that market, in the absence of widespread adoption of these filters.

That said, we can look more closely at the volatile organic compound (VOC) emissions from the same test to put the results in context.  We showed that there were 4.38 mg of tailpipe emissions over our EQUA test, or 0.03 mg/km.  This compares to the most relevant official limit of 100 mg/km for total hydrocarbons, which puts the car more than 99% below the limit.  These low emissions were compared to the 330 mg emitted from the tyres on the same test.  But, still, how bad is 0.03 mg/km?  A recent paper, from March 2022, in Environmental Science & Technology by Wang et al, measured the VOC emissions from four humans seated in a controlled climatic chamber, using proton transfer reaction time-of-flight mass spectrometry and gas chromatography.  Without the presence of ozone, the emissions averaged 2.2 mg per human per hour, rising to 4.6 mg in the presence of ozone.  Averaging these, and applying the result to the length of the EQUA test, it would imply that a human driver would emit 12 mg of VOCs in total.  Therefore, during the EQUA test the driver may have emitted three times more pollution from his body than came out of the tailpipe of the car being driven.  Stop metabolising stuff!

So, we can see that the levels of regulated exhaust pollutant emissions from the FHEV are now trivially low.  Of those not regulated, the sub-23 nanometre, ultrafine particles are probably the greatest omission, which is being addressed by regulators soon, as set out below.  What is left is a more serious concern about VOC emissions, especially from tyres.  There are three main reasons we should be concerned about such emissions.  First, VOCs can have a direct health effect through inhalation or contact with the skin – many are harmless, but the worst organic compounds can be carcinogenic.  Second, VOCs can react in the air to create ‘secondary organic aerosols’ (SOA), i.e. new particles, for which the health and environmental effects are well described elsewhere.  Third, these organic compounds have an ‘ozone formation potential’ (OFP), ground-level ozone being one of the main constituents of the smog hanging over city skylines.

From the testing on the Tesla and Kia described above, we see tyre VOC emissions of 2.2 mg/km from the Kia and 6.1 mg/km, from the larger-wheeled Tesla.  Taking the ‘secondary organic aerosol formation potential’ (SOAFP) for five target compounds and the average value for the remainder from Wang et al (2017), this implies a maximum possible particle formation of between 0.03 mg/km and 0.1 mg/km.  The latter is shown in the table below, which is from the Hankook tyre on the Tesla.  This may sound low, but tailpipe particle emissions are now as low as 0.02 mg/km, so the tyre VOC emissions could more than five times the tailpipe mass emissions.  

Using a similar approach for ozone formation, the test could have yielded up to 13.2 mg/km.  There are no direct regulatory benchmarks to compare this to, however.

This shows not only that tyre size matters, but that chemical composition does as well.  From over three hundred tyres tested by Emissions Analytics, the surface area of light duty vehicle tyres – from which the VOCs evaporate – can vary by around 100%, depending on whether you have a 155/60 R15 skinny summer tyre, or a 235/65 R17 specialist SUV tyre, for example.  Across 73 tyre manufacturers tested, the proportion of aromatics – some of the more potentially toxic compounds, and highlighted compounds in the table above – vary in concentration from 78 to 582 micrograms per milligram of sample.  In other words, the concentration of certain chemicals, and the surface area from which they can evaporate, varies significantly between tyres.   As a consequence, vehicle size and weight, with the tyres that accompany that, evidently affect emissions in use, in addition to the materials required for their construction.

This shows not only that tyre size matters, but that chemical composition does as well.  From over three hundred tyres tested by Emissions Analytics, the surface area of light duty vehicle tyres – from which the VOCs evaporate – can vary by around 100%, depending on whether you have a 155/60 R15 skinny summer tyre, or a 235/65 R17 specialist SUV tyre, for example.  Across 73 tyre manufacturers tested, the proportion of aromatics – some of the more potentially toxic compounds, and highlighted compounds in the table above – vary in concentration from 78 to 582 micrograms per milligram of sample.  In other words, the concentration of certain chemicals, and the surface area from which they can evaporate, varies significantly between tyres.   As a consequence, vehicle size and weight, with the tyres that accompany that, evidently affect emissions in use, in addition to the materials required for their construction.

What does this mean for regulation?  The current Euro 7 proposals are generally a sensible step, as set out in a previous newsletter, not least to make the regulations more technology neutral and tighten ultrafine emissions limits.  A less prominent part of the proposal is to tighten the ‘evaporative emissions’ test. This is designed to limit the VOCs off-gassed during refuelling and the use of vehicles, for example vapour escaping from the fuel tank.  The test is conducted in a controlled chamber and the escaping VOCs collected over a one-hour period when the vehicle is hot followed by 48 hours when it is cool, all with the ambient temperature varying across a ‘normal’ range.  Currently, the total emissions must be less than 2 grams, although this may be significantly reduced with Euro 7.  This is relevant because the test, although not specifically designed to do so, will pick up off-gassing from the vehicle’s tyres.  However, this is one respect in which Euro 7 is not technology neutral: the evaporative test only applies to gasoline vehicles.  So, BEVs with large tyres have no limits applied.

In conclusion, we have shown the risks of myopically looking at tailpipe emissions, and the dangers of asserting the environmental impact of vehicles simply from the type of powertrain.  In short, environmental logic points towards a mixed car parc made up mainly of smaller BEVs to cover town driving and larger FHEVs for more general purposes, brought about as quickly as possible in order to get the black hole of older, dirty cars off the road as soon as possible.  Vehicle weight, and hence emissions, should be minimised to allow the smallest tyres that are safe and effective.  This is a lower risk approach, and from an economic point of view a ‘lower regret’ option as we would not be gambling resources of potentially up to $1 trillion globally, according to some reports, on a maxi-BEV technology that may not deliver its promises.  If we pivot to this lighter approach, in ten years’ time, as with 1990s Britpop Oasis’ champagne supernova, you might not have to wipe that tear away now from your eye.

Emissions Analytics wins Tire Technology Environmental Achievement of the Year

“We appreciate the award from Tire Technology International as a reflection of the team’s dedicated work on a topic that was previously of marginal policy interest, but which is now thrust into the limelight by the ever-growing weight of SUVs and battery-electric vehicles.” - Nick Molden Emissions Analytics founder and CEO

Last night (March 21, 2023), Emissions Analytics were announced as the winners of Tire Technology International Award for Environmental Achievement of the Year.

The awards were coordinated by Tire Technology International magazine and were officiated by a panel of international journalists and industry experts. The awards featured an array of categories to recognise the different innovation and achievements over the last 12 months.

Presentation: Emissions Analytics Tire Technology Expo Presentation 22 March 2023

CEO & Founder, Nick Molden spoke at the Automotive Tire Technology 2023.

Do No Harm

How efficiency does matter

In our last newsletter we showed how the energy efficiency of vehicles is not the only consideration in decarbonisation.  We should also think about efficiency of resource allocation.  Resources are scarce, and the job of decarbonisation is big, so we need to invest our money carefully.  One way to judge this is to consider an alternative measure of optimality: Pareto efficiency.  Vilfredo Pareto was a nineteenth century Italian economist, who described a system being Pareto efficient when is not possible to change the allocation of goods without harming at least one person.  Interpreting that for transport decarbonisation, we can say that a change of powertrain can be a Pareto improvement if it is possible to improve all relevant aspects without disadvantage to someone.  For clarity, following Pareto improvements does not necessarily lead us to the globally best outcome, but offers relatively easy ‘wins-wins’, opportunities which are scarce in complex modern economies.  What can this tell us if we apply it to some real-world test data?

To study this, Emissions Analytics performed a comparison test between a Tesla Model Y and a Kia Niro full hybrid electric vehicle (FHEV), on its real-world EQUA test cycle conducted in the UK in March 2023.  The vehicles were less than one year old, equipped with the original tyres, with similar tread depths, and closely matching odometer readings.  Both are standard size sports utility vehicles, with the same number of seats, while the Tesla is physically slightly larger.  Importantly, due primarily to the 78.1 kWh battery, the empty weight of the Tesla was 489 kg greater.  From a driveability point of view, this is offset by almost treble the power and double the maximum torque.  The detailed specifications are shown in the table below.

Selecting the appropriate pair of vehicles presented various dilemmas, and the conclusion was that there is no perfect answer.  Perhaps the most obvious approach would have been to compare the hybrid to a Kia Niro EV.  From an engineering point of view this would have been a good like-for-like comparison.  However, Emissions Analytics is committed to understanding what happens in the real world and, therefore, it would be unwise to the neglect the biggest selling battery electric vehicle (BEV) by revenue in the world in 2022, the Tesla Model Y.  The pairing of this with the Niro hybrid reflects a common choice that real customers are making, even if that means a technically less perfect comparison.  As evidence of this being a good comparison, the table include effective monthly lease costs, which shows there is less than 10% difference.  These figures assume the buyer is a company car driver paying the higher rate of income tax in the UK, which reflects the most common type of buyer; the difference is caused by the low benefit-in-kind tax on the BEV. The mix of incentives varies around the world, some more generous, some less so.
 
With the background of climate change and Dieselgate, there is a strong narrative that we need to “stop burning stuff” to solve our environmental problems.  Non-combustion sources of emissions, such as from tyres, typically get dismissed as just big chunks/having no air quality effect/not very toxic/inconvenient.  At the same time, some BEV owners report that they see lower tyre wear, and other higher wear compared their previous internal combustion engine (ICE) vehicle.  However, it has been unclear whether there has been simultaneous behaviour change, in terms of driving style or routes, or the measurements are unreliable.

For this test, the vehicles travelled in convoy to eliminate any effects of driving style or climatic conditions.  The Kia was instrumented with a tailpipe Portable Emissions Measurement System (PEMS) and the Tesla with an equivalent mass.  The test cycle was made up of five repeats of the EQUA cycle, totalling 741 km.  At regular points through the test, all the wheels were dismounted, cleaned, weighed and remounted to calculate the mass loss.  The results, compared to the relevant regulatory limits, are shown in the table below.

The mass loss data points and trend over the total distance are shown in the chart below.

The first striking result is that there are almost no tailpipe pollutants measured from the Kia except carbon dioxide (CO2).  The gasoline particulate filter reduces particle mass to almost zero, and particle number to 97% below the Euro 6 regulatory limit.  Every air pollutant is comfortably more than 90% its limit.  While there is no limit value for CO2, compared to the average of all the current-generation gasoline vehicles we have tested, the Kia is 38% lower at 113.4 g/km.  The Tesla is, of course, zero on all these measures; we are ignoring upstream emissions in this test.

Turning to the non-exhaust, the second striking finding is that tyre wear mass emissions are five orders of magnitude greater than particle mass from the tailpipe.  This is two orders of magnitude greater than in previous tests by Emissions Analytics on different vehicles.  Further, tyre wear emissions were 26% greater from the Tesla, due to the extra weight and torque, despite their being specifically-designed ‘green tyres’ for electric vehicles.  The gap may have been greater had the car not been equipped with special EV tyres.  In absolute terms, the increased tyre wear was 11 mg/km, which is 2.4 times the maximum permissible tailpipe particle mass emissions.

So, as tailpipe air pollutants were tending to zero from the Kia, it is a fair summary to say that a consumer choosing between switching from a traditional gasoline internal combustion engine (ICE) vehicle to either a Kia Niro hybrid or a Tesla Model Y, is weighing up an extra 62% point reduction in CO2 against a 26% increase in particle emissions.  However, if full lifecycle CO2 emissions are taken into account, BEVs currently offer around 50% CO2 reduction on average, so in reality the decision to opt for the Tesla is between 12% points of extra CO2 reduction compared to the ICE baseline but 26% more particles.  

How robust is this conclusion?  In other words, would we get a very different answer if we had chosen a different FHEV/BEV pair of vehicles?  From Emissions Analytics’ wider EQUA programme, we have tested many different vehicles for tailpipe emissions and tyres for wear rates.  From this we conclude that the key factors in the relative emissions at the whole-vehicle level are the vehicle mass and torque, the model year and the tyres the vehicle is equipped with.  Therefore, it is of little significance that the Kia Niro is physically smaller than the Tesla Model Y, as the differences in mass and torque are representative of the typical of choices that consumers are making in today’s market.  What this shows is that the vehicle manufacturer’s choice of tyres is increasingly important in overall emissions, both for tyre wear and CO2 via rolling resistance.

What does this mean in terms of the concept of Pareto efficiency set out at the start?  Moving from a gasoline ICE to the hybrid would be a Pareto improvement: it is better on every measure.  But moving from the gasoline ICE to the BEV is not such an improvement, due to the increase in tyre particles.  So, given gasoline ICEs are predominant at the moment, the optimal and most efficient move in terms of scarce resource allocation is to move to FHEVs, not BEVs.

But it doesn’t end there.  Tyres don’t just affect the environment in terms of a mass of small particles.  Also important are the number of particles emitted and chemicals that leach out of them over time as they settle on soil or in water, as well as the vexed problem of handling end-of-life tyres.  A neglected further effect is volatile organic compounds (VOCs) that ‘off-gas’, or evaporate, from the surface of the tyre all the time.  Similar compounds are also released from the tailpipe, although they are regulated only as part of a ‘total hydrocarbons’ measure.  Which is greater – VOCs from the tyres or the tailpipe?

During the same test above, we measured tailpipe VOCs using Emissions Analytics’ proprietary sampling equipment that allows a full speciation using two-dimensional gas chromatography and time-of-flight mass spectrometry.  These VOCs matter as they are a precursor to smog formation and contribute to the secondary formation of particles in the air, as they react chemically.  These effects are in addition to the direct health effects, especially for aromatic compounds, which are often carcinogenic in certain concentrations and exposures.  Within that group, polycyclic aromatic hydrocarbons (PAHs) and nitro-aromatics are typically the worst.

Large samples from one tyre on each vehicle were also taken and placed in a ‘microchamber’ heated to 20 degrees Celsius, around the temperature of a vehicle certification test, and held at that level for the same duration of the on-road EQUA test – around three-and-a-half hours.  The off-gassed VOCs were analysed and quantified, and then scaled up by the relative surface area of the sample to that of all four tyres on the vehicle.  The results are shown in the table below.

This shows that VOCs off-gassed into the air from the tyres are about two orders of magnitude greater than those from the tailpipe of the Kia.  Adding the tailpipe and tyre sources, we see that the Kia had total emissions less than half of the Tesla’s.  This result is driven by the larger diameter and width of the Tesla tyres, despite their being lower profile.  These results will be unpacked further in a future newsletter, but for now we can see that they are consistent with the pattern of the regulated pollutants: there is very little coming from the tailpipe relative to tyres.  

In this context, the concept of Pareto improvement is reminiscent of the no-harm principle in medicine: primum non nocere. ‘Do no harm’ means taking a step back from an intervention to look at the broader context and mitigate potential negative effects on the social fabric, the economy and the environment.  By switching to FHEVs we can create a ‘no harm’ intervention, unlike BEVs.  That is not to say that FHEVs emit literally zero, but no additional harm is done and, in fact, improve all aspects.  That is also not to say that BEVs and their associated tyres might not improve – they very likely will.  At that point, it would then be right to change policy.  To the trade-off described earlier – between 26% more particles as the price of 12% points of extra CO2 reduction – no verdict is passed as to whether this is a good trade-off from a policy point of view, but a trade-off it is.

In the meantime, FHEVs are the win-win, do-no-harm option, while BEVs are the win-lose, the vexatious trade-off in a situation of significant technology uncertainty.  On this basis, and of Pareto efficiency, until BEVs reach certain performance characteristics, government and industry support should be switched immediately from BEVs to FHEVs to create maximum welfare.

Webinar: The effects of renewable fuels on combustion emissions

Our CEO & Founder, Nick Molden presented a webinar on the effects of renewable fuels on combustion emissions on 14th March 2023. To watch the webinar and download the presentation please see below.

The webinar covering the latest results on the effect of renewable fuels on combustion emissions, which has been conducted together with the University of Oxford.  It will look at the chemical composition of renewable fuels, consider the impact that has on tailpipe emissions, and see how well Euro 7 may capture these effects.  The presentation will cover:

• Profiling the organic compounds in fuels

• Using this information as a fingerprint to understand provenance

• Measuring speciated organic compounds from the tailpipe in real-world driving

• Results from the latest on- and off-road testing

• Relationships between the chemical composition of fuel and exhaust pollutants

Webinar: Route map to Net Zero Construction

Emissions Analytics is pleased to welcome Daniel Marsh and Carl Desouza from Imperial College London as our guests to discuss the “Route map to Net Zero Construction.”

Construction machines are typically diesel powered and, depending upon their age and application, can produce relatively high levels of NOx and particulates in urban environments. The construction industry is determined to reduce its environmental impact and meet NetZero targets, but choosing the right path can be daunting when numerous alternatives exist. There is no one size fits all solution.

Our webinar will discuss results from various projects that were led by Imperial College London, alongside Emissions Analytics’ real-world emissions testing services.

This is not intended to be a definitive guide or to provide prescriptive answers, simply to share independent test results and support sharper industry discussion.

Efficiently wrong

The danger of fixating on one thing

Battery electric vehicles are great.  There – we said it.  In fact, we have been saying it all along.  But are they so great that all competition should be banned?  Or are they great, but with caveats, such that we should foster choice and spread our decarbonisation bets to ensure the best and most certain reduction in carbon dioxide (CO2) emissions?  Banning your competitors can variously be described as state-sponsored monopoly, central planning and rent seeking.  Ironically, communist China isn’t banning alternatives to battery electric vehicles (BEVs), yet free-market Europe is.  Is there any merit in Europe’s current position, and how can this paradox be explained?

One explanation is how the notion of ‘efficiency’ is being misused.  Roughly speaking, diesel engines are 30% efficient in converting chemical energy in the fuel into kinetic energy of the vehicle, while a vehicle battery converts around 90% of the energy stored into motion.  Much of the difference is in waste heat.  In fact, Carnot’s theorem, based on the second law of thermodynamics, shows that a ‘heat engine’ has a theoretical upper limit of efficiency well below 90%. So, the argument goes, as we are short on low-carbon energy sources, how efficiently we use that energy is vital. And electrical motors powered from a battery at 90% efficiency must easily trump a diesel engine at less than – say – 50% efficiency. Therefore, BEVs are a no-brainer and any resources put into any other technologies must be wasted.
 
This can be encapsulated in the following syllogism: we need greater energy efficiency in road transport; BEVs are more energy efficient; therefore, we must have them.  
 
There are many flaws in this argument.  First, we must step back and remember that the aim is to reduce CO2 emissions.  Does greater efficiency always correlate with lower emissions?  No-one doubts that efficiency is important, but it is everything?  On the first question, this is true in many circumstances.  For example, if a diesel car delivering 40 miles per gallon is replaced with a new diesel car at 50 mpg, CO2 emissions will fall in the usage phase.  Greater efficiency means lower CO2. In contrast, however, as countries increasingly switch from E5 to E10 gasoline – that is, gasoline containing a maximum 5% and 10% of ethanol respectively – the combustion efficiency falls due to the lower volumetric energy density of the fuel, yet CO2 emissions also fall. In this case, CO2 falls despite worse efficiency.  What this shows is that efficiency does correlate with reduced CO2, but only necessarily so when all other things are held the same.  In the latter case, the type of fuel has changed.  Overall, though, it is clear that efficiency and CO2reduction do not correlate as a general statement.
 
The second aspect to consider is that greater efficiency may lead to reduced CO2 emissions, but with some other effect. Walking, for example, is highly energy efficient and very low CO2 even when undertaken by carnivores, but it’s not going to get you from New York to Los Angeles very quickly.  Equally, walking can be efficient, low CO, quicker cheaper, as seen for many short journeys in congested city centres.  What this shows is that efficiency is only one of the relevant variables in the decarbonisation equation.
 
With Dieselgate in mind, there is some validity in the argument that combusting fuel in urban areas needs to be eliminated, and BEVs are the only scalable option to achieve this.  However, this idea neglects the significant differences in pollutant emissions between older and newer vehicles.  The latest generation of cars, sold since the introduction of the Real Driving Emissions regulation from 2017, sees the average gasoline vehicle emitting nitrogen oxides (NOx) of 11 mg/km (82% below the regulated limit) and particle number emissions of 0.9 x 10¹¹ #/km (85% below), and the equivalent value for diesels of 43 mg/km (46% below) and 0.1 x 10¹¹ #/km (98% below) respectively – data collected from Emissions Analytics’ EQUA test programme.  The proposed introduction of Euro 7 will further tighten the limits and, more importantly, will widen the boundaries of the test and cold-start requirements such that these real-world values will fall further.  
 
As a result, modern ICE cars are not the ones causing urban air pollution problems, but rather the earlier, Euro 5 and 6 vehicles. Euro 5 gasoline vehicles average 39 mg/km of NOx (35% below the limit) while diesels emit 806 mg/km (4.5 times the limit). The priority must be to remove these older diesel cars and, whether they are replaced by new internal combustion engine (ICE) vehicles or BEVs, is largely irrelevant. The Ultra Low Emission Zone in London is a big step in this direction, even though it continues to allow many high-emitting Euro 6 diesels into the city, and does not discriminate on vehicle mass.  With typical ICE vehicles emitting 67 mg/km of tyre particles, compared to 81 mg/km for equivalent BEVs, there are some downsides to these heavier vehicles.  In short, this shows the logical fixation with ‘combustion’ being inherently bad is also wrong.  Of course, this fixation is closely related to the efficiency error.     

The logical fallacy against combustion is shown by synthetic ‘e-fuels’, where hydrogen and CO2 are removed from the air using low-carbon electricity and then synthesised into, for example, gasoline in such a way that as much carbon is absorbed during production as is released during subsequent combustion.  The combustion itself will still be at low efficiency, but the net CO2 will be close to zero and, due to the purity of the fuel, the pollutant emissions can be very low as well.  Low CO2, low pollutants, yet inefficient.

So, why don’t we go straight to e-fuels, and bypass the additional problems of material scarcity and dependence on China that comes with BEVs?  The answer is that we do not have sufficient low-carbon electricity to power the process.  This is where BEV supporters have a point: green electricity is scarce, so we must use it efficiently.  However, what they are proposing is swapping one scarcity for another: scarce green electricity for scarce battery and motor components.  Scarcity matters, especially where the scarce goods are disproportionately controlled by a limited number of entities, as it leads to them enjoying excessive ‘economic rent’ through using that market position.  Building a diversity of supply is a necessary first step, to accommodate growing demand.  

While many BEV proponents complain about excessive profits of fossil fuels companies, their vision would recreate the same issues just with different players.  More concerning still is that European’s act of giving BEVs a future powertrain monopoly has given disproportionate market control to China.  The US has reacted with a major $369 bn dirigiste policy to break China’s control.  The EU is now poised to unveil a ‘Green Deal Industrial Plan’ to match this.  The trend of ever-freeing world trade is now well in reverse, as countries take an increasingly protectionist and mercantilist approach designed to maximise exports while minimising imports.  Had Europe reacted to the need for decarbonisation by playing to its competitive advantage – especially building low-carbon electricity grids – this value-destroying cycle may never have been triggered.

Such an error by European governments, arguably to assuage Dieselgate, has radically polarised the debate.  Anyone who doesn’t ‘get’ the BEV story and its efficiency myth is labelled as a climate change denier.  Our aim must be to limit the overall negative effect of climate change in the least damaging way.  So, let’s consider an alternative, pragmatic path.  It’s simplistic, but balances practicality, cost, geopolitics and – not to be neglected – social welfare.

It should be noted that only in the second phase is efficiency the key dynamic.  The attraction of this approach is that it helps manage the significant uncertainties and risks in the effectiveness and timing of the stages of decarbonisation.  For example, the BEV-led phase could be accelerated or pushed back depending on technological advancements or setbacks.  Looked at another way, these stages are necessary if we are not to blow our carbon budget under the Paris Treaty.  All are needed.  Hybrids only get you so far, but they are here now.  E-fuels are net-zero in principle, but not realistic today.  BEVs cannot be scaled today without prohibitive cost.

As a side note, hidden in here is a paradox for the BEV lobby: enough green electricity is needed to allow the manufacture and charging of cars to be low carbon, but too much green electricity would enable competitor fuels and powertrains.  We should look out for lobbying focused more on powertrain transition than grid capacity building.

In conclusion, BEVs can be great products and will play a significant role in decarbonisation on almost any scenario.  But why ban the competition?  The argument that efficiency is so much better that we should gamble all our investment on this horse is ill-conceived, costly and risky.  It is perhaps just very clever rent-seeking, supported by parts of an excitable environmental lobby.  Once efficiency is seen within the proper context of costs, alternatives and negative side-effects, the merits of a diversified, staged, pragmatic transition to a net-zero world become clear.  BEVs then can be best understood as a transitional technology to a fully decarbonised, competitive, welfare-maximising future.

Presentation: How to reduce emissions of micro particles from tyres to minimise health and environmental impact and avoid reputational damage

CEO & Founder, Nick Molden spoke at the Automotive Tire Technology 2023.

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How tyre emissions hide in plain sight

But it's not especially an electric vehicle problem

Emissions testing is usually preoccupied by testing for known, worrisome chemicals in the environment. Often they are in small amounts or concentrated at hotspots.  Sophisticated equipment is deployed to find and measure them.  We obsess with ever-tighter regulation of these pollutants we know about, even well beyond the point of diminishing environmental returns.  At the same time, emissions from tyre wear from vehicles are all around us, and inside us, but we hardly see it.  There is so much of it, and it is camouflaged by its chemical complexity, that we don’t notice.  It is visible but unperceived.  We urgently need to reprogramme our perceptive faculties to recognise the danger right in front of us.

Recent peer-reviewed scientific research estimated that a median adult excretes 11.8 nanograms per kilogram of bodyweight of 6PPD and 6PPD-quinone in urine per day.  These chemicals have been made famous by ground-breaking research on the West Coast of the US, which linked them to mass fatalities of coho salmon – and more recently various types of trout.  6PPD is a preservative present in almost all tyres and few other products, which forms 6PPD-quinone when it reacts with oxygen in the air, and this is the chemical that kills the fish.  We covered this in an earlier newsletter.  Now, the data on human urine from South China, which is soon to be published, strongly suggests that when we emit, we pass tyre emissions.

Emissions Analytics has been testing for the rate of tyre wear emissions in real-world conditions over a number of years, across thousands of miles on many different types of tyre.  The current average wear rate for a whole vehicle is 67 mg/km from new tyres, and this is predicted to halve over the tyres’ lifetime.  Therefore, particulate mass generated from tyre wear is nearly 2,000 times greater than that from the tailpipe of modern ICE vehicles, as previously reported.  In addition, our testing suggests for every 500 kg extra vehicle weight – about the mass of a large battery – tyre wear emissions rise by 21%.  By some, this has been interpreted as an attack on BEVs, as they are heavier.  While it is true that this comprehensively disproves the notion – bizarrely incorporated in legal statute in many countries – that BEVs are zero emission, a better interpretation is that all tyre emissions are high compared to the tailpipe particle mass from the latest ICE vehicles.  To complete the picture, it should also be recognised that tyre and tailpipe emissions approach parity when the comparator is an older diesel vehicle with no particulate filter installed, or on a vehicle with a compromised filter.

Therefore, we should not call the tyre emissions issue exclusively a BEV problem.  The trend towards heavier ICE sports utility vehicles has been a contributor to these growing emissions rates as well.  In fact, having now tested over 300 different tyre models for their chemical composition from around the world, there is an emerging picture that specialist BEV tyres designed to handle the greater weight and torque of the vehicle may contain fewer potentially toxic compounds.  So, the wear rates may well remain high if the driver is using the available torque, but in terms of environmental damage this may be offset by better formulations.  This mitigation does tend to come at a higher purchase price, however.  It does further mean that, if a BEV is equipped with non-specialist tyres – most likely when the owner replaces the original manufacturer tyres – the emissions could be higher in both wear and potential toxicity.  We will present further results on these innovative formulations in a later newsletter.

This analysis makes it clear that tyre wear emissions are being generated when any of the world’s 1.5 billion cars are driven.  Latest estimates suggest they shed about 6 million tonnes of tyre material per year, or 4 kg per car per year.  It is often suggested, however, that this is not a big problem, because the particles shed tend to be larger and get caught in storm drains and filtered out, or sit harmlessly by the roadside. There are many reasons to doubt this.  First, in many countries, the particles are filtered out from storm drains and road run-off, but the resulting sludge is then sold back to farmers for fertiliser.  Another undesirable form of circular economy.

By our estimates, around 10% of the total tyre particulate matter is airborne – primarily the ultrafine particles – but a majority is often said to settle on the land.  Recent peer-reviewed scientific research from Casten et al in Environmental Science & Technology studied the uptake, metabolism and accumulation of tyre wear particles and derived compounds in lettuce.  It found that 6PPD and 6PPD-quinone – among other compounds – were “…readily taken up by lettuce…” via the roots and then translocated to the leaves in a way that “…may be of concern to consumers.”  The paper describes how tyre wear particles may leach derivative compounds even before entering the soil, but that “…the majority of compounds are expected to be released once TWP [tyre wear particles] enter the agricultural soils and come in contact with soil pore water.”  This provides a challenge to potential regulation to understand derivative chemicals and their toxicity, as well as the original particles.

Fortunately, to aid this process, Emissions Analytics’ test programme aimed at mapping the chemical composition and leaching potential from tyre wear is progressing apace.  Our subscription database has recently been expanded to add over one hundred tyre models from the US market – across light- and heavy-duty vehicles – to add to the hundreds of samples from the European market.  The results help confirm one finding: that tyres are extremely complex and sophisticated in their construction.  While this is impressive from an industrial and technology point of view, it helps create the problem set out at the start of this newsletter: the complexity helps camouflage their presence all around us in the environment.

To illustrate this, we took one high-selling tyre from a major European manufacturer and took samples from five different locations: inside and outside tread, the centre band around the middle circumference, and the inside and outside sidewalls.  It was expected that the inside and outside tread composition should be similar, as only some performance tyres have asymmetric construction – this was indeed the case for the tyre tested.  The centre band was expected to be different as it needs properties including conductivity, although the differences were relatively small and specific.

But what of the comparison between the outside tread and outside sidewall?  The tread primarily has exposure to the physical stresses caused by driving, while the sidewall helps maintain the structural integrity while being exposed to sunlight much of the time.  The chart below shows the 25 most prevalent organic compounds found – using our specialist two-dimensional gas chromatography and time-of-flight mass spectrometry method – plus 6PPD. The average number of compounds found was 350 per sample. The scale is in nanograms of compounds per milligram of tyre sample, expressed logarithmically.  The coloured areas represent the tread and sidewall respectively.

This shows that the sidewall has higher concentrations of certain chemicals, not least androstan-17-one‚ 3-ethyl-3-hydroxy-‚ (5α)-, which is a chemical found naturally in nutgrass, and lends certain properties to the tyre.  It is also higher in naphthalene‚ 1‚6‚7-trimethyl-, which is part of the naphthalene group and known to be harmful if swallowed and very toxic to aquatic life at certain concentrations, with potentially long-lasting effects.  The tread has higher concentrations of other chemicals, for which many have little or no toxicological information available.  An exception is 1‚1'-Biphenyl‚ 2-methyl-, which is a known skin irritant, can cause eye damage, and affect the respiratory tract.  Perhaps surprising, the concentration of 6PPD was higher in the tread than the sidewall, despite the sidewall being more exposed to sunlight.

These chemicals are all important to understand, and they can affect the environment in multiple ways. The tyre gets abraded, and the resulting particles can get inhaled or ingested by humans.  As they settle on soil they can enter the food chain, as can particles that enter the waterways and either end up as drinking water for humans or inside fish and other animals then eaten by humans.  Chemicals on the surface of the tyre can also react with the air or other chemicals to produce derivative products with toxicological effects, as with 6PPD leading to 6PPD-quinone. Such reactions can also lead to the formation of secondary organic aerosols, i.e. more particles.  All along, chemicals originally bound up in the tyre particles may leach out at different rates and with different effects.

We conclude from this that, while different parts of the tyre have different chemical compositions, reflecting their different roles, many of the compounds are common.  We are now able to identify both these common compounds and the differentiating compounds, which makes possible wider, targeted environmental monitoring to understand the sources and ultimate fate of tyre emissions.  It also opens up paths to reducing the environmental impact, such as the California Environmental Protection Agency’s proposed targeting of 6PPD, which will force tyre manufacturers to consider alternatives.  It is the assessment of the properties of the alternatives which will be important, to ensure we don’t switch one problem for another.

So, as you drizzle your salad with some tasty, oily dressing, you now know that the lettuce itself may be carrying various compounds that originated from the crude oil used to make the tyres, that wore as you drove to work, and that settled on the neighbouring farmer’s field.  These chemicals are all around us, and inside us.

At least, however, we now know what to look for and can measure them out in the real world.  Their camouflage is blown.