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How Much Electricity Will Electric Cars Use?

July 27, 2017

By Paul Homewood



Best electric cars 2017 UK


There have been various attempts to estimate the amount of electricity needed for electric cars.

So let’s get it straight from the horse’s mouth.

Below is the spec for the Nissan Leaf, showing electricity consumption of 150Wh/Km.


Actual performance is always much worse than manufacturers say, whether petrol or other. We also know that electricity consumption will rocket when heaters, lights, windscreen wipers and so on are turned on.

It would not be unfair to add 30% onto Nissan’s figures, giving 195 Wh/km.

Assuming an average annual mileage of 12000 miles (19200 km), we get 3.74 Mwh.

With about 30 million cars on the road, that would total 112 TWh a year.

Total electricity consumption last year was 304 TWh, so there would be an increase 37%.

Assuming the cars were recharged throughout the day at the same rate, they would increase demand by 12.8 GW.

However, it is more likely that, at best, charging would have to take place during just 12 hours, either overnight or early evening. In that case demand would double to 25.6 GW.

It’s all a bit back of fag packet stuff! But it’s a good base to start from.

Many drivers would want a much bigger car than the Leaf, and many would do higher mileage. On the other hand, others could do less.

And to complicate matters, we’re not sure where we stand with hybrids. The Tory manifest specifically stated that all cars must be zero emissions by 2050, which eventually rules out hybrids.

However, it seems likely that they will be seen as a halfway house in the meantime.

It is only my view, but given the problems with charging, particularly for those with no off road parking, many drivers will simply use their hybrids as conventional cars, simply filling up with petrol. While this will help with electricity demand, it will do little to help with CO2.

  1. Jack Broughton permalink
    July 27, 2017 6:44 pm

    Interesting to compare with Euan Mearns figures, (about a year ago).
    He used 22 Wh/km and came up with a demand of 122TWh for the UK.
    I’d say commendable agreement between two separate estimates.

    Would suit short-journey school-run type drivers and save them money.
    No use to longer journey people unless great improvements occur.

    • Jack Broughton permalink
      July 27, 2017 9:07 pm

      Sorry, 220 Wh/km.

  2. Robert Jones permalink
    July 27, 2017 6:55 pm

    Horrifically, I suspect that your analysis is better than the Government’s, pre-supposing that one was actually carried out! In which case we are all doomed. Repeal the Climate Change Act (2008) and scrap the Climate Change Committee with immediate effect!

  3. Jack Broughton permalink
    July 27, 2017 7:01 pm

    Note that the range is only 120 km and the charging time nearly 7 hours.
    The only attraction is that the fuel cost is 0.3 p/km as against 6 p/km for my diesel: but that does not allow for the tax-revenues to be replaced if electric cars expand.

    • July 28, 2017 3:57 am

      Now that’s something that seems to have been quietly overlooked or not mentioned to date. When fossil fuels cease to be used, they won’t be attracting taxes, levies or any other government skimming (including GST here in Australia), so that money is going to have to be gouged from somewhere else, isn’t it. I wonder how they’ll work that one out.

    • bea permalink
      July 28, 2017 7:10 am

      120 km is pretty much the safety margin for me when I am driving. The point at which I start getting a little nervous, and am looking out for a garage. IMAGINE driving on the M1 in winter, stuck in a jam, and the range notice in the electric cars of ten thousand people on the same bit of road says 20 km! Mass psychosis! And how are the self-driving cars programmed to handle this! Mass electronic psyschosis!

      • It doesn't add up... permalink
        July 28, 2017 11:17 am

        I’m quite content to see my fuel gauge go down to 10 miles remaining so long as I’m not out in the countryside because that is actually pessimistic, and in any case I can find a petrol station easily. It would be a nightmare trying to find a charging station on the same basis, and the risks of battery levels proving inaccurate or too dependent on weather conditions would be considerable.

  4. July 27, 2017 7:24 pm

    I’m sure that a degree of sanity will return to our elite establishment masters before proper cars are banned from the roads.

    • Graeme No.3 permalink
      July 28, 2017 12:02 am

      Sanity would return far faster if government limousines for Ministers were replaced by electric cars — “so they could set the example”.

      • NeilC permalink
        July 28, 2017 7:13 am

        That should apply to all the green blob ideas. Let those who advocate these “wonderful” ideas be the guinea pigs, so we rational people can judge to accept or decline.

  5. July 27, 2017 7:24 pm

    Also interesting in that table they include nonsense units for charging, ie: kW/hr. it makes me wonder about the level of accuracy and scientific literacy we are dealing with.

    • Joe Public permalink
      July 27, 2017 9:42 pm

      Surely that figure is to indicate its maximum *rate* of charging?

      The majority of homes have a single-phase grid connection, allowing charging at up to ~7.5 kW, but the *basic* Leaf can only be charged via a 3.5 / 3.6 kW/hr charger.

      • July 28, 2017 12:42 am

        Yes Joe, kW is a rate of charging. And I think most here would know they mean kW. The point is that people use units quite incorrectly. It shows a lack of understanding of what is really going on. Strictly the unit kW/hr is a rate of change of power. Energy kWh vs power kW vs rate of change of power kW/hr. Who cares, it’s all the same eh. The only place I’ve seen rate of change of power used is in generator output response, the ramp rate, measured in MW/s.

  6. DougS permalink
    July 27, 2017 7:44 pm

    It’s 150 Watts per km!

    • DougS permalink
      July 27, 2017 7:48 pm

      150Wh/km, I must learn to type.

  7. Joe Public permalink
    July 27, 2017 8:02 pm

    1. “The Tory manifesto specifically stated that all cars must be zero emissions by 2050, which eventually rules out hybrids.”

    Not necessarily, as I replied to an Oldbrew comment on your ‘Revealed: Government’s electric car revolution could cost more than £200bn’ posting

    (Hybrid) ICE may use artificial, manufactured ‘natural’ gas, or, H2 fuel-cell.

    2. The US Dept of Energy has a ‘Compare Side-by-Side’ site, and Tesla info is here:

    Their 2017 90D Model S’s energy consumption is shown as 32 kWh/100 mi – 200 Wh/km

    3. Tesla’s site is interesting in that scrolling down to its interactive Range-per-Charge section the effect of changing speed, external temperature, using its heating, using its aircon, (& changing wheel size) can be seen. Strangely, it doesn’t mention battery degradation, which presumably is linear.

    [Not necessarily noted for absolute figures, but indicative for % change.]

    A 10K drop in outside air temp reduces range by ~5%.

    Using it’s aircon reduces range by ~8%.

    Using it’s heating reduces range by ~7%.

    Cruising at 70mph vs 55mph reduces range by ~25%.

    Opting for 21″ wheels rather than 19″, knocks ~2% off range.

    • Joe Public permalink
      July 27, 2017 8:09 pm

      Another interesting gem on Tesla’s site is the rate of energy transfer from a 7.4kW (home) charger.

      When I had a diesel, my local Tesco pump filled its tank at an energy transfer rate of approx 3 minutes for 700 miles range [i.e. a rate of 14,000miles/hour(!!)]; Tesla’s 7.4kW Home Charger rate is 22 miles/hour

  8. CheshireRed permalink
    July 27, 2017 8:02 pm

    It seems like a hasty decision plucked from the remnants of a lost legal case. Perhaps it’s designed to kick the legal challenge into the long grass for now and will be refined (ie rolled back) once its true cost & logistical implications become clear?
    Either way it’s clearly a huge undertaking and obviously hasn’t been remotely thought through. There will be many arguments to come over this one.

    • RogerJC permalink
      July 28, 2017 7:06 am

      It was in the Conservative Manifesto for the June General Election, but I can’t remember anyone commenting on it at the time.

  9. July 27, 2017 8:56 pm

    Reblogged this on Climate Collections.

  10. Steve Borodin permalink
    July 27, 2017 9:52 pm

    If we ever have another General Election, I am running very short of people to vote for!

    • July 28, 2017 4:03 am

      You are not alone. Perhaps this is just another way of discouraging voter engagement.

  11. July 27, 2017 10:25 pm

    Can the Govt. afford to lose the fossil fuel tax,or have they got another driver bashing plan up their sleeves.

  12. Dermot Flaherty permalink
    July 28, 2017 12:24 am

    Paul, I missed this thread earlier and on another thread (“New Diesel and Petrol cars banned from UK roads by 2040”) I am also trying to work out the power requirements (i.e. Grid Capacity) to charge 30M electric cars.
    Can you please explain how you got your figure of 12.8 GW demand if the 30M were charged throughout the day ?
    Is it simply your annual energy requirement of 112TWh divided by 365 then divided by 24 ?
    That gives 12.8GW demand or, as you say 25.6GW if over a 12-hour night period.
    (So that’s 8 Hinckleys).

    But doesn’t your charging scenario assume a very smart grid intelligently talking to the car chargers carefully matching demand to power requirements such that each car is just getting a trickle feed of what it needs to top it up ?
    If tomorrow night, 30M Leafs plugged in to the grid at – say 20:00 – after all had been driven during the day and they used the lowest charging option on the above chart, then why isn’t the power demand 108GW (30M times 3.6kW) – 30GW greater than the official DUKES figures for the UK generating capacity in 2016 ?

    I’d can’t see why each car isn’t going to try to draw as much power as it can with the result that the Grid will collapse.

    • July 28, 2017 9:19 am

      It’s 112 TWh/yr, divided by 8760 hours = 12.79 GW.

      But as you say, that’s assuming the load is spread evenly across 24 hours, which not realistic

      • July 28, 2017 8:54 pm

        Isn’t that why the grid operators worry about millions of electric jugs being switched on when the Coronation Street programme finishes?

  13. John F. Hultquist permalink
    July 28, 2017 1:13 am

    The photo is not a Nissan Leaf. The Leaf looks more like a real auto and not a golf cart.
    Photo is of an ultra-compact called the Nissan New Mobility Concept:

    • Henning Nielsen permalink
      July 28, 2017 9:59 pm

      Looks like a Renault Twizy:

      “The Renault Twizy is a battery-powered 2 seat electric city car designed and marketed by Renault and manufactured in Valladolid, Spain.[1][2] Legally classified in Europe as a heavy quadricycle (light quadricycle for the lower-powered Urban 45 model), the Twizy has a maximum range of 100 km (62 mi).”

  14. July 28, 2017 6:29 am

    Can we conclude this plan is insane? The self-righteous warmists and their like need to be sectioned!

    • bea permalink
      July 28, 2017 7:33 am


      Their reality-therapy would be to bicycle round and round the M25 on the hard shoulder, facing the traffic, with a sign saying, “I’m gonna ban you sinners!”

      Meanwhile, a straw in the wind? Or an anchovy in the current?

    • CheshireRed permalink
      July 28, 2017 8:41 am

      This scheme is primarily aimed at improving air quality rather than reducing CO2 but yeah, it’s certainly insane! Hybrid to 30-40 mph would be my chosen path; that would mean almost all urban driving would be zero-emissions while maintaining range and not collapsing the grid due to demand.

  15. GICASI permalink
    July 28, 2017 6:42 am

    All the assumptions use yesterday’s technology. I wonder if graphene (in conjunction with Li-ion batteries and as photon-capturing paint) and stand-alone mini Thorium nuclear reactors might be necessary to achieve this pipe dream. And a pig flew past my window…

    • bea permalink
      July 29, 2017 12:02 pm

      Or fusion reactors:

      That young goodlooker is now NINETY YEARS OLD.

  16. July 28, 2017 7:43 am

    The BBC talking up commercial EVs – Bristol features with its electric buses … the piece swerves economics and actual numbers – I wonder how much those Brissle buses cost? – the BBC’s aversion to discussing the actual operating costs in an honest fashion is simply disgraceful (I now don’t expect any different – but can’t let go of the idea that they should be doing the job properly….)

    The biggest electric commercial outfit – Smith seems to have trouble paying for its web site hosting – and the resale value is small – see eBay

  17. rwoollaston permalink
    July 28, 2017 9:44 am

    I think you need to add a figure for power distribution losses – I believe this is around 30%. There are also losses in charging the batteries of around 10%?

    • It doesn't add up... permalink
      July 28, 2017 11:07 am

      Power losses are about 2% in the high voltage grid and another 4-5% in the low voltage distribution network. Those figures may increase as we move away from local power stations to wind farms offshore and in Scotland, and solar farms all over Devon and Cornwall.

  18. Bitter&twisted permalink
    July 28, 2017 9:45 am

    How many idiots does it take to charge an electric car?
    About 200,000, rich, BBC, listening, Guardian reading ones.
    That is the limit of the non-compulsory market.
    Now I’m off to irritate my green neighbour by firing up my 1962 Jaguar Mark2.

  19. prismsuk permalink
    July 28, 2017 10:32 am

    Professor Paul Howarth CEO of the National Nuclear Laboratory [NNL] thinks it’s a done-deal to decarbonise our energy use by 2080, with a boost of the National Grid from 80 GW now up to 320 GW, with 75 GW [or even 100 GW] of nuclear, 100 GW of renewables and 100 GW of FF with carbon sequestration.

    This is well worth 12:30 of anybody’s time to take on board the way the Government might have to accept at least 100 GW of nuclear and if FF with carbon sequestration proves to be a non-starter, maybe double that:

    • rwoollaston permalink
      July 28, 2017 12:54 pm

      One of the things he said had to be done to make nuclear attractive to investors is to ‘de-risk’ the financials. In layman’s terms, that equals subsidy. Nuclear and renewables currently attract subsidies – largely funded by general taxation – roughly equivalent to the wholesale market price of electricity. In other words, their output is 50% subsidised. With this expansion of the grid, we will therefore see this cost going up significantly either to be met by energy condumers of to be funded by general taxation, or both. This will be in a world where fossil fuelled power costs are coming down. Will be able to prosper, compete and enjoy our current standard of living? Will we be like Germany where the poor can’t afford to heat their homes? Subsidies need to be transitional tools. He made no mention of an objective of nuclear being affordability and competitiveness with fossil fuels, so it is likely the subsidies will carry on.

      • July 28, 2017 1:16 pm

        Buying an electric vehicle also gets a government subsidy. All these subsidies are going to pile up while at the same time income from fuel duty shrinks to zero.

        Does not compute.

  20. Stonyground permalink
    July 28, 2017 11:48 am

    ” The Tory manifest specifically stated that all cars must be zero emissions by 2050, which eventually rules out hybrids.”

    It rules out the Nissan Leaf as well if we’re being honest.

  21. July 28, 2017 12:12 pm

    I’ve still yet to see anyone proposing this “idea” address the problem of people being able to charge their cars at home if they don’t have their own off-street parking.
    Even for people who can usually park outside their own home on the public street (though this is never guaranteed), are they going to be allowed to string cables across the pavement (answer: no) or are thousands of miles of residential road going to be fitted with a charging point every car-length – and at what cost?

  22. Peter Flint permalink
    July 28, 2017 12:22 pm

    Putting aside the electric car issues which are well documented I’m waiting to see the government proposal for converting lorries to electric. Given the huge number on our roads and the distance they cover I think this is an area that needs focus.

  23. July 28, 2017 12:25 pm

    So you can go about 70 miles in something akin to a baby carriage (pram for you). Be still my heart. Let’s see, I drive my Ford Freestar van about 450 miles to my brother’s in Knoxville, TN for Christmas–with a cat. This motorized grocery cart should be fun. And if you are hit by an oncoming truck you end up as a smear across the road.

  24. July 28, 2017 1:11 pm

    In your calculations did you account for charging efficiency? Protagonists of Lithium Ion claim “close to” 100% charging efficiency (i.e. the same amount of electricity comes out as goes in). However this ignores the losses (mostly resistive heat) in the actual charging electronics that convert grid voltage (a/c) to car line voltage (dc).

    Modern switch-mode power supplies have very high conversion efficiency (95-97%), so are pretty good – but taking battery losses and charger losses together we’re probably talking about at least 5% in additional losses.

    If so you should add circa 5% to the overall power requirement. Not an insignificant amount.

  25. dearieme permalink
    July 28, 2017 1:13 pm

    Will the Mullahs who will be running the country in 2050 give a hoot about emissions? If they are in the pay of the Saudis (if Saudi Arabia still exists) they may be all for internal combustion engines.

    • Athelstan permalink
      July 28, 2017 5:22 pm

      You try and separate a young Pakistani from his gaz guzzlin’ wheels and he will probably give you a quote on separating your windpipe from the neck down.

  26. Dermot Flaherty permalink
    July 29, 2017 12:15 am

    If anyone would like to find out what the National Grid has been doing about our future energy security, then it has been pointed out to me that they have a set of Future Energy Scenarios (FES) which make interesting reading and I recommend the following two in particular – and
    It shows that at least the Grid folk are seriously looking at how the implied energy needs are going to be met.
    Note what the Forecourt thoughts paper states re. Gove’s all-electric target –
    What might 2050 look like?
    In the first place most, if not all, cars will be pure electric vehicles (EV). There will be no place for the ICE and the motoring infra-structure will be geared towards the EV. This EV dominance will have been driven by a number of factors such as:
    – the national desire to meet the 2050 carbon reduction targets
    – the desire for cleaner air
    – the desirability of these newer products
    – the probable relative cheapness of EVs.
    There are approximately 32 million cars on the road
    today. In our Future Energy Scenarios we anticipate half this number will be EVs in our
    greenest scenario by 2033 and in our less green but prosperous scenario by 2042.
    Consumer Power: sees the most aggressive rise in peak demand. This is brought about by
    less engaged consumers who use electricity when it suits them. The potential impact that
    unmanaged mass EV charging, particularly at peak time, could create is significant. In such
    a scenario, challenges to operating the system, generation and network capability will need to be addressed if we are to have a network that is safe, secure, reliable and economical.).

    So demand management at a number of levels is envisaged (back to my point about uncontrolled plugging in on EVs).

    Finally, in view of Paul Howarth's view of the future, I looked at the Electricity Supply section to see how the Grid viewed power requirements and generation in 2050 and perhaps unsurprisingly, the picture is different. I am a fan of nuclear but I don't know enough to comment on either picture. One thing seems clear and that is that a fleet of Hinckley Point Cs cannot be the answer.

  27. Dermot Flaherty permalink
    July 29, 2017 11:07 am

    Re. the FES studies I referred to above, Paul has already commented on these at the following –

  28. Gamecock permalink
    July 29, 2017 12:55 pm

    No government/parliament has authority over subsequent governments/parliaments.

    Today’s government declaring what the government is going to do 20+ years out is too stupid for comment.

  29. Coeur de Lion permalink
    July 29, 2017 2:20 pm

    I worry but not much about that high voltage. First electrocution headline?

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