In our government’s universe, a small flash of green on a number plate will both demonstrate virtue and drive a green economic recovery

Preamble: EVs

I like EVs. However, I think that banning the ICE alternative is asinine. Similarly, I like Champagne, but would object on principle to a law banning sparkling Shiraz.

Main Discussion: Green Haloes

Around these parts EVs are not as rare as they used to be. Probably 1 in a hundred cars that I see are now electric, I think. You will have noticed EVs with increasing frequency wherever you happen to live. Newer ones are easily told from a distance by the green flash halo on their number plate. In “No Smoke Without Tyres” I highlighted this in the featured image. The rest of the colour scheme was chosen to mimic a poster for 1931’s Curse of Frankenstein. No-one will have noticed, but rest assured that some thought does go into these things.

Anyway, about that green flash. How did they come about, and what are they for? A quick rewind 2 years:

Green number plates are set to be rolled out from autumn, Transport Secretary Grant Shapps confirmed today (16 June 2020), under plans to drive a green economic recovery.

As part of the government’s plans to achieve net zero emissions by 2050, drivers will be encouraged to make the switch to electric vehicles through the introduction of green number plates.

Good, yes. This paragraph makes perfect sense. Just not in this universe. Their green haloes enable the virtuous to penetrate sacred zones that the rest of us sinners have to pay to enter. The appearance of the green plates followed a consultation in 2019, which explained:

The commitment to consult on the use of green number plates for ULEVs was a flagship announcement by the Prime Minister at the UK’s international Zero Emission Vehicle (ZEV) Summit on 11 September 2018.

I can see how a green flash on a piece of plastic would be a “flagship announcement” for our government. (Note: this was Theresa May, not the present Prime Barnacle.)

In “No Smoke Without Tyres” I also noted the possibility that, owing to their increased weight, EVs might cause more particulate pollution than new ICE cars. But no-one can argue that they produce more CO2 than ICEs.

Or can they?

A few months ago, some sceptics got rather excited about a study by Volvo cars which compared the carbon dioxide emissions from an electric and ICE version of the same vehicle, the XC40. Volvo undertook a full life-cycle analysis of both models, from etracting raw materials to scrapping. The bottom line was that the EV had to be driven a bagillion miles (I exaggerate slightly) to emit less CO2 over its lifetime than the ICE version.

At this news the table banged my sceptic’s funny bone. Jit, (the sudden pain shouted into my ear), that must depend entirely on how much CO2 is emitted by the generators that supply the electricity for the battery, hence whatever number they put on this is clearly wrong, and even if it was right, it varies from country to country and is changing moment to moment as the grid mix in each country changes! And some people will charge at home from solar panels!

It just seemed like a too-handy piece of favourable data that a sceptic could use as a four by two to bash their opponents rather than an authoritative statement of fact. So I filed the story in a pigeon hole labelled “investigate the actual facts later” and moved on.

Well, later eventually became now, so here we are. What are the facts of this Volvo study?

Figure 6 from the Volvo study

In terms of carbon dioxide emissions, the ICE vehicle wins in the extraction, refining, construction and disposal stakes. It incurs 16 tonnes CO2(e) of Gaia’s wrath up to the completion of its construction. By contrast the annual per-capita CO2 emissions of the UK in 2020 was 4.66 tonnes.

The (e) means equivalents, so the per-capita value for the UK is slightly low. And 2020 was lockdown city. But handwaving all that out of the way, buying a new shiny Volvo XC40 costs you 3.5 times the average UK resident’s annual CO2 allowance.


The EV incurs 25 tonnes CO2(e) of Gaia’s wrath by the time it is built – about 5 years of a UK resident’s carbon dioxide allowance. Of the total, 7 tonnes is emitted in building the battery.

It is interesting that so much of the emissions arise even before the manufacturing stage:

Table 5 from the Volvo study (“functional unit” means a car driven 200,000 km).

[Regarding the manufacturing itself, Volvo makes the XC40 at two plants, one in Gent, and one in Luqiao. No prizes for guessing where the Chinese plant gets most of its electricity. Is there an irony here?]

So the ICE starts out 9 tonnes “better” than the EV, but inexorably catches up as it burns fuel across its lifetime. Depending on the generation mix of the electricity grid, this takes 47,000 to 146,000 km. If your grid is similar in carbon dioxide intensity as the world average, it takes 146,000 km for your ICE to overtake the EV in the sinfulness stakes. If your grid is entirely wind powered, it takes 47,000 km. And it’s somewhere in between for the EU average grid.

Bearing in mind the planned lifetime of their cars (200,000 km), Volvo say that in their new EV they’ve made something better for the environment than their ICE petrol. (They no longer make a diesel model…)

My version of the basic calculation is as follows: when you roll your new car off the forecourt, if it’s ICE, you have 9 tonnes of Gaia’s goodwill banked in your centre caddy. Then, you burn through that credit at the rate of 163 g per km. Assuming that the EV is recharged solely by the purest green means, then the distance for you to catch up in sinfulness with your twin who bought an EV on the same day you bought your ICE is an easy calculation: it’s

9,000,000 g CO2/ 163 g CO2/km = 55,000 km

[163 g is the book value used by Volvo, which might be (harrumph) a tad on the optimistic side. My distance value is higher than theirs, presumably because they account for extraction and refining the petrol.]

To put it another way: if you buy a new ICE, that’s 16 tonnes of CO2 accounted for as soon as you turn the key (you probably don’t turn the key these days). At the XC40’s 163 g CO2/km, that’s the equivalent of about 100,000 km of actual driving. So if you really cared about CO2, you wouldn’t buy a new car. You’d keep the old one running. The calculation gets worse of course if you opt for the EV: the equivalent running of your old car in terms of CO2 emissions to match the production emissions of the new EV is 150,000 km.

Let me just screech to a halt and say: I don’t care about carbon dioxide emissions from your tailpipe or in the manufacturing of your car. As far as I’m concerned, I would be pleased for you to choose the car you like, whether that be EV or ICE. I am more concerned about real pollutants, which until recently I thought the EV won at. Now (as highlighted in “No Smoke Without Tyres”) I’m not so sure.

However, if you care about CO2 emissions, you should not think that you are polishing your green halo by buying an EV, or that your green halo is worth polishing in the first place.

The first driver to get a green plate fitted was Transport Secretary Grant Shapps, who had a Tesla Model 3 adorned with the eco-conscious-signalling registration mark. Shapps said: “Green number plates will help increase awareness of cleaner vehicles on our roads, demonstrating that a more environmentally friendly transport future is within our grasp.”

[That’s the same Shapps who used to boast about his 3 high-end cars, 6 bedroom house and aeroplane to flog his “get rich quick” pamphlet retailing at $1000 but discounted to $197 for the first lucky 250 purchasers:]

As everyone knows, it doesn’t matter how many sins of emission you have committed in the past, so long as you buy an EV now.

Commenting on green plates, Edmund King, AA president, said: “Having a green flash on the number plate may become a badge of honour for some drivers. We support this concept which shows that the EV revolution is now moving from amber to green.”

Autoexpress, link as above

A badge of honour, huh? Does Mr. King think honour is so easy to come by?

After all, as someone once said, virtue is its own reward.


The evidence is that the green number plate signals virtue but does not demonstrate it. EVs have no tailpipe emissions, but whether they contribute to clean air locally is debatable. For those who care about carbon dioxide emissions, not buying a new car at all seems to be the better choice.

Featured Image

Three proposed designs for the green number plate.


  1. I commented a little while ago about NZ’s scrappage scheme, to encourage people to scrap their old “polluting” cars and buy new EVs instead. I seem to remember we had a similar scheme in the UK a few years ago. I thought at the time that it was counterproductive, and you clarify nicely why I was right.

    Of course, if you want to maintain jobs in the car industry, it might make sense. However, it should be clear by now that we can’t “save the planet” AND at the same time maintain society as we know it.


  2. Jit,

    I’m holding out for the Hawkins warming stripe number plate. I don’t just want to buy myself into heaven, I want controlling shares.

    Liked by 1 person

  3. jit; that’s a good analysis but there’s a fundamental error in the Volvo study’s approach of using various grid averages for the CO2 intensity of the power used to charge the EV.
    Any new EV is an incremental demand on the grid which does not arise if the customer buys an ICE vehicle. In the UK, as in most other countries, renewables are prioritised onto the grid (behind only nuclear) so there is no spare renewable capacity to meet the incremental demand of a new EV.
    Therefore said demand is met by the incremental power source – gas in the UK or possibly coal – no matter what tariff the EV owner may be on.
    Unless/until there is a consistent surplus of renewable energy available (tip: don’t hold your breath!), the power for incremental demands such as EVs and heat pumps will come from fossil fuels.
    On that basis, aiui, the CO2 emissions to power a new EV work out about the same per mile as a modern diesel.
    As you say, there is the benefit of removing exhaust pollution from towns and cities but that is marginal given the relative cleanliness of new ICEs.


  4. Mike, I didn’t really think about that angle, but took Volvo at their word. Their best case scenario (a grid powered solely by wind) may be impossible, but as just that – a best case scenario – it makes a reasonable baseline to kick off with.

    There may well be excess renewable generation some of the time once we have overbuilt renewables to a wasteful extent, so that at times energy is being thrown away, while at other times it is still in short supply. [If we continue down this crazy green path.] Sometimes the times of plenty will be when people want to charge up, sometimes not. There may well sometimes be excess power from wind at night, so that EV owners won’t be straining the grid – juggling availability and demand necessitating all the “smart” add-ons.

    There is also looming over the 100% wind scenario the question about the CO2 costs of wind turbine construction. However, turbines would seem to beat EVs in those stakes in that they are in use more (most?) of the time, and so pay back the initial outlay faster. (EVs, like other cars, spending 90+% of their lives parked.)


  5. In terms of the energy return on energy invested (EROI or EROEI) it seems from the analysis by professor Mike Kelly of Cambridge (see the link below) that current modern renewable generation schemes (wind and solar) are much poorer than traditional energy systems (e.g. fossil and nuclear fuels, plus traditional hydro). And once the buffering schemes, which are required to level out their inherent variability, are accounted for then these modern renewables are mostly totally inadequate for sustaining a modern economy. [Of course, this may be their advantage from some people’s perspective!] Thus the green, or pseudo-green, halo slips a little further.

    Here is the link – sorry it is rather long! See particularly Figure 2.


    Liked by 3 people

  6. Jit; while I agree that the best-case scenario provides a baseline, it is hardly a realistic one unless you live somewhere like Norway or France.
    Yes, the UK might reach the point, many years from now, when there is a regular over-production of renewable power and – most important – the means to store it and to distribute it around the country. In my view that point is a very long way off. Over the next few years we will be retiring a lot of baseload capacity and it will take roughly 3 units of renewables to replace one of dispatchable, even on an average basis. In addition demand is likely to increase with the drive to electrify everything.
    Until any incremental demand is met by renewables – from storage or even idled wind/solar farms – studies like this should use the incremental power source as their baseline. (home generation excepted, of course).


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