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Emissions Analytics argues that current Pareto-efficient solution for decarbonization would be hybrids, not BEVs, based on do-no-harm

Based on comparison tests between a Tesla Model Y and Kia Niro full hybrid, independent emissions testing company Emissions Analytics (earlier post) is suggesting that at present full hybrids are the win-win, do-no-harm option for decarbonizing transportation, while BEVs are a win-lose option, hampered by a “vexatious” trade-off between CO2 reductions and increased in-use vehicle emissions—specifically from tire wear particles as well as off-gased VOCs from the tires.

On this basis, and of Pareto efficiency, Emissions Analytics argues, until battery-electric vehicles can reach certain performance characteristics, government and industry support should switch immediately from EVs to full hybrids to create maximum welfare.

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.

—Emissions Analytics

Emissions Analytics compared the two vehicles using its real-world EQUA test cycle. The two vehicles were less than one year old, had their original tires with similar tread depths, and closely matched mileage. The Tesla is physically slightly larger, and weighs 489 kg (1,078 lbs) more, due mainly to the battery pack.

Acknowledging that a good textbook like-for-like comparison would to have been pairing the Niro hybrid with the Niro EV, Emissions Analytics said that it “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 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 below.


Source: Emissions Analytics

The testing showed that the Kia’s gasoline particulate filter reduced particle mass to almost zero, and particle number to 97% below the Euro 6 regulatory limit. Every air pollutant is more than 90% its limit. Compared to the average of all the current-generation gasoline vehicles the company has tested, the Kia is 38% lower at 113.4 g/km. The Tesla is, of course, zero on all these measures; upstream emissions were ignored in this test.

However, the testing also showed that tire wear particle emissions were five order of magnitude greater than particle mass from the tailpipe of the Kia. Tire wear particle emissions were 26% greater from the Tesla, due to the extra weight and torque, and despite the tires being specifically-designed for electric vehicles. In absolute terms, the increased tire wear from the Tesla over the Kia was 11 mg/km—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.

—Emissions Analytics

In addition to the unaddressed issue of chemicals that leach out of the tire wear particles (TWP) over time, there is also the effect of volatile organic compounds (VOCs) that ‘off-gas’ from the surface of the tire all the time. Similar compounds are also released from the tailpipe; these are regulated as part of a ‘total hydrocarbons’ measure.

During the testing, Emissions Analytics 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. Large samples from one tire 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 analyzed and quantified, and then scaled up by the relative surface area of the sample to that of all four tires on the vehicle. The results are shown below.


Source: Emissions Analytics

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.

… 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.

—Emissions Analytics



I've got nothing against BEVs.

I do however have a great deal against fat-arsed luxo barges flaunting faux ecological credentials.

Not only are they resource intensive to build, they as this study shows are in comparison to lighter, slower cars heavily polluting to run.

Yeah, sure, in the world of fake comparisons, they come off well against a comparably heavy and massively accelerating ICE, but neither should be built, or if they are, with very high penalties, not incentives, to recognise the damage they do.

They are also inherently dangerous for other road users, not just for their occasionally fiery batteries, but due to their weight and acceleration.

Here is the NTSB:

"I'm concerned about the increased risk of severe injury and death for all road users from heavier curb weights and [the] increasing size, power, and performance of vehicles on our roads, including electric vehicles," she told attendees.'

Contrary to what many assume, I also have always had severe reservations about fuel cell cars, and advocate hydrogen and derivatives largely for heavy long distance transport and long term energy storage, for the simple reason that current fuel cell cars are also very heavy, although they don't inherently have the unsuitable for safe road use acceleration of BEVs.

They come into their own for larger vehicles, so if everyone, ludicrously, insists on driving SUVs then they start to be more viable.

In Europe, financing electro luxo barges has largely driven the smallest class A cars off the road to hit fleet targets for electrification, and the little cars have not got the margins when penalised.

None of this is the end of the world, and improved batteries and fuel cells will mean that we can get the best of all worlds.

In the meantime city BEVs with limited range or hybrids of one type or another are what we can actually build economically with good overall pollution characteristics and safety,

There is not much ecological about fat, heavy, dangerous, resource heavy Model Ys and their ilk though.


So: the BEV is heavier and creates more particulate pollution than a HEV.
The HEV has a higher carbon footprint then the BEV, although this depends on the source of the electricity.
The BEV also has higher ecological construction costs (battery and engine materials).
So we have to equate three quite different things.
IMO, the "do no harm" approach is not much use, you have to combine the N sources of harm in some way and look at the overall, not as a series of binary decisions.


They conveniently don’t consider CO2 to be an air pollutant as it is three orders of magnitude greater than what they are focused on. How myopic.



GO2 is a rather different issue, and as you say, the balance for that between hybrids and BEVs will be rather different, depending on the energy source for the electricity.

Like for like, slow and light wins there too though., so BEV for BEV, and hybrid for hybrid, a lot of the cars touted as being ecological ain't very.



Have another look at their figures.
They reckon they have taken CO2 into account:

' 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. '

So you pays your money, and you takes your choice......

Bernard Harper

The flaws are obvious with this study. They did not test true like-for-like designs, account for ICE degradation (planned obsolescence) or how EVs can have almost unlimited lifespans. It makes no account in improvements in tyre technology and road surfaces over the greatly extend life of the vehicle or that EVs have almost zero brake wear. We are also near near peak battery mass IMO. Subsequent generations of batteries will get much lighter with improved chemistry. And as recharging becomes faster range anxiety will become moot when five-minute top-up charging is commonplace. Buying a new hybrid now when they are likely to increase pollution and collapse in value is not recommended. Avoid.


If G W Bush hadn't killed
Partnership for a New Generation of Vehicles , we would have been well into decarbonization.


Most of the grid is fossil fueled sequester power plants to clean it up



This study is looking at the situation now, not what may, or may not, happen when and if various technologies improved as much as enthusiast's hope.

And I have no idea where your notion of unlimited lifespan for EVs comes in.
The longest warranty for the batteries in private vehicles I am aware of is 15 years, and if you have an old clunker of a car, putting in several thousand dollar's worth of new batteries may not be a sensible or realistic investment, especially given the income levels typical of people who own old cars, with the original more minted owners having long since sold them.

Exactly that is happening right now with the Nissan Leaf, which had a pretty rubbish battery pack, and those cars are far more likely to get scrapped way before the typical life of an ICE car than last longer than them.


I would guess that there is a fudge available, or remedial action, according to taste.

Some sort of particle grabber by suction from the tyres.

That may ensure the God given right of people to maim and kill others by driving enormously heavy and massively accelerating cars on the public highway.

Ecological, my........



When they frame it as 12% of this vs 26% of that they’re obfuscating the magnitude of this and that. In this case it is 12% of 113,400 mg of CO2 vs 43 mg of pm2 or 13,000+ mg of CO2 vs 11 mg of PM2.



Yeah, the particulates weigh less.

But they do a wonderfully effective job of killing people without hanging around about it like GHG do.

Not to mention contributing generously in the case of tire particulates to plastics in the ocean and the food chains there.

Small, light and slow helps all the metrics, whether hybrid or BEV.

Bling luxmobiles, BEV, hybrid or FCEV don't.


@SJC, yes, probably easier to deal with exhaust from stationary sources...
+ get rid of coal and lignite (Germany ...)


Just to put some of this into perspective, including my own whinging about heavy BEVs, here is this from Europe:

' based on extensive testing evidence, the ICCT has now revealed that about 13m highly polluting diesel vehicles sold from 2009 to 2019 remain on the roads. A further 6m diesels have “suspicious” levels of emissions, the ICCT said. The cars span 200 different models produced by all the major manufacturers.'

This is largely straighforward use of cheat devices etc, criminally and lethally intentionally seeking to defraud over the years, with neither the directors nor the shareholders through jail and billions of damages and fines held to real account.

Lying sociopaths deliberately misleading about their product, including autopilot which ain't, and the ecological 'benefits' of owing a heavy car with unsuitable acceleration are simply continuing an industry tradition established way back when the health benefits of lead in petrol were more widely appreciated by the likes of General Motors.

They don't make lies like they used to, for which we should all be grateful.

Roger Pham

I would argue that current Pareto-efficient solution for DECARBONIZATION would be Plug-in hybrids (PHEVs) to be charged strictly from excess wind, solar energy, nuclear, and hydro-electricity instead of pure BEVs charged from fossil power plants, or non-plug-in hybrids that still depend on petroleum.

What's needed is day-time charging at the work place using Solar PV mounted above the parking well as Wi-fi connected smart charger inside the vehicle that would allow nightly charging only on windy nights when there for sure will be plenty of wind energy. When charged twice a day, a PHEV capable of 40-mi electric range can travel 80 miles a day on just electricity alone.

In this way, the electric grid will be able to handle much higher influx of Renewable Energy (RE) and that would incentivize much higher penetration of RE, while ensuring that there will be NO charging when the grid has high power demand during very hot summer days or very cold winter days, or during cloudy and calm days. There is NOT much advantage for a PHEV or BEV when charged during times that the grid has to rely entirely on fossil-fuel power plants, because this will just require the use of more peaking power plants that aren't efficient and yet more polluting than baseload power plants

Furthermore, the PHEVs should be designed with very small and light-weight engine. like a 3-cylinder 1-liter engine that is only needed to provide steady base-load power, while the power for acceleration and deceleration will be provided by the e-motors and the battery pack. This will make future PHEVs having similar weights and hence efficiency to comparable HEV or ICEV.

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