In I Dream of EV, potentilla says:
I would be interested to know whether charging at home in the UK is really “still good value” compared with gasoline or diesel if the equivalent fuel taxes were applied to electricity.
So would I. potentilla quotes this from The Guardian:
“Despite recent falls in the price of petrol and diesel, the cost of charging at home is still good value compared to paying for either fuel, but again underlines just how the rising cost of electricity is affecting so many areas of people’s lives.
“We’re also aware that public chargepoint operators are having no choice but to increase their prices to reflect the rising wholesale costs they’re faced with, which will heavily impact drivers who have no choice other than to charge up away from home.”
Well, it was time for me to revisit my calculation of which was cheaper: petrol or electricity? My conclusion a year ago, based entirely on useful energy at the wheels, was that electricity was 50% more expensive than petrol pre-duty and VAT, and that all in, petrol was 33% more expensive than electricity. But that was then. What is the situation now?
Setting forth to gather the numbers for a new calculation, I suddenly realised that I already had part of the data that I needed because I had gathered it for another of my interminable anti-EV rants, Slips the Green Halo.
[I am not of course anti-EV. I’m anti banning ICE. There is a distinction.]
In that post, the reader will remember, I reported on Volvo’s lifecycle analysis comparing two different versions of its XC40 – an electric one and a petrol one. The EV started out in more “carbon debt”, if you’ll excuse the horrible phrase, but caught up as the ICE car burnt more and more fuel, until each was as bad as the other after both had driven 90,000 km or so. (Based on the EU’s electricity mix.)
As the EV retails at £20,000 more than the ICE, at least a few of its new owners would be hoping for some savings on running costs. And so far they have had them – although as we never tire of pointing out, this is a situation that only pertains because of the duty that is slapped onto petrol.
BASIC DATA – FUEL AND ELECTRICITY COSTS
Petrol has gone up a lot lately – for our international readers, it was about £1.30 per litre when I made the relevant calculation a year ago. It capped out here a month or so ago when a few retailers were shamefacedly writing numbers like 200.9p on their forecourts. It has climbed down from those vertiginous heights and in this neck of the woods its average cost today (27/viii/2022) according to Confused.com is £1.704.
Working back from VAT downwards: ex VAT, the cost is £1.42 per litre. Knock off the duty (presently 52.95p per litre) leaves you with £0.8905 per litre base cost.
There are two ways to obtain electrons for your EV – you can plug it in at home and take advantage of domestic rates of electricity and 5% VAT, or go to a public charger and bear the commercial markup and the 20% VAT.
Domestic: On this day (27.viii.2022) Ofgem says that the price cap rate – which is in effect the price everyone in the UK not lucky enough to have obtained a fixed deal some while ago is paying – was £0.28 per kWh. The figure includes the 5% VAT. So ex-VAT, it’s £0.267 per kWh.
Commercial: There is nearby to your present author a much-vaunted charging station run by an outfit called Gridserve. At their premises it is possible to plug in for a rapid charge and retire aloft for a holy moccachino. On the Zap Map website, there is mostly high praise for Gridserve, with apparent power flows of over 100 kW for suitable machines. Their fee? £0.45 per kWh, including 20% VAT. The number leads this cynic to speculate that they are operating at a loss in order to build a customer base. Ex-VAT, it’s £0.375 per kWh.
The car data mostly comes from Volvo. There are two values for energy use per km for the EV, one from Volvo and a slightly less flattering one from ev-database. Tankheim.com provides a larger figure for the ICE range than I calculate based on the CO2 emissions per km, so there are two figures for that too.
EV: The battery is 78 kWh, and depending who you ask, it either uses 240 Wh/km (Volvo) or 357 Wh/km (ev-database). The book range is therefore 325 km from 100% to empty and the range calculated based on the ev-database figure is 218.5 km.
ICE: the tank is 54 l, and the range calculated based on the book 163 g CO2/km is 775 km. The Tankheim given range is 1054 km. Perhaps the difference here and for the EV represents ideal vs real conditions, I’m not sure.
So, we are now ready to make our calculation. This will give a cost in pence per km for each vehicle for both range scenarios, and for the EV, for the two charging scenarios. We just take the cost to brim the tank/battery from empty and divide by the estimated range.
- PRE DUTY AND VAT
The cost to brim the ICE from empty is £48.09. Remember, this is ex duty and VAT. To brim the EV from empty at Gridserve is £29.25, and at home, it’s £20.80. With the different range estimates, here’s how that looks in pence per km:
The most pessimistic scenario for the ICE beats the most optimistic scenario for the EV. Conclusion: without duty and tax, petrol is cheaper than electricity.
2. POST DUTY AND VAT
To brim the ICE is now £92.02. To brim the EV at Gridserve is £35.10. At home, it’s £21.84. Here’s how that looks in pence per km:
There is some overlap, but the cheapest scenario is domestic charging if the book range is obtained. Even with duty and taxes, there is no advantage if the EV driver has to use the commercial charging service. Conclusion: domestic charging of the EV looks to be the marginal winner – but only because of government policies.
3. THE FUTURE
The new energy price cap comes in on the 1st October. The price may be seared into UK citizens’ minds, but for our international readers, the price we will pay is £0.52 per kWh. (I know. I hardly believe it myself. But these are the days we live in.) So how will the domestic charging cost shake out in six weeks’ time? It will then cost £40.56 to brim the EV at home. In terms of how that looks in pence per km? The professional-eyed among you will have noticed a couple of red dashed lines in the second column chart. These show the cost per km for home charged EVs after 1st October. Assuming that the petrol price does not begin to rise again, domestic charging will be more expensive than filling up the ICE car at the pump, even with the most pessimistic range for the ICE and the most optimistic range for the EV. (12.5 p/km for the EV vs 11.9 p/km for the ICE.)
THE FINAL INSULT
The duty on fuel and the VAT on top can be seen as a carbon tax. How much does it work out at in terms of £/tC emitted, I wondered? Here is that calculation:
The density of petrol is approximately 0.755 kg/l. Using decane as an example species gets you 0.638 kgC/l. [The rest being H.] Therefore, for every 0.638 kg of carbon emitted, us unreconstructed ICE drivers are paying 81.35 p in duty and tax (that number is the difference between the pump price and the price without duty and VAT). It is easy to see that it is more than a pound per kilo C emitted, which is therefore more than a thousand quid per tonne of C emitted. In fact, it’s
£1275 PER TONNE C EMITTED
This service is brought to you by the department that also invented the asinine “levelling up” slogan. You’re welcome.
Please alert me if I have made an error in calculations. I have laid these out as clearly as possible so that it is possible for the reader to check my homework. Note that the carbon tax calculation does not take into account the fact that our petrol is now mostly “E10” – that is to say, 10% bioethanol. I think including it would make the calculation worse. EVs may be less expensive to maintain than their ICE brethren. The XC40 is not the smallest car available, so these costs in pence per km are on the high side, both for the EV and the ICE.
[CAVEAT ADDENDUM: As Mikehig points out in comments, time of use tariffs are available that offer very good rates of electricity at unearthly hours, i.e. when there is no demand. Such tariffs will no doubt trump the cost of petrol, even in the brave new world of October 1st.]
There seems to have been a boom in solar panel sales. Naturally the best solution all round would be to have a nice detached house with a car port, on which one could affix solar panels that would charge an EV with free electricity. It would be your second car, of course! Unfortunately this solution is not available to the majority of the people of the UK.