Fun with numbers - what if we all had electric cars

Qs - would we have enough electricity generating capacity if each household in the UK had one electric car? And would we have to reduce the number of miles we drive every year?

A - I don't know, but here's how I would guesstimate it.

(Feel free to pile in if you have better info, or just skip to the conclusion in my later post.)
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Typical daily electricity usage per household - 9.25 kWh (from here).

Check: Total electricity generated/used in the UK per annum 335 TWh (from here), 30% of which is domestic (from here) = 100 TWh. 28 million households x 9.25 kWh x 365 days = 94 TWh.

That's (say) 16 hours a day, grid running at near full capacity.

That leaves (say) 8 hours where not much electricity is being used, in which time power stations, if they continued running at near full capacity, could generate (say) another 40% x 335 TWh = 134 TWh, = about 13 kWh per household/car per day.

A typical electric car, like a Nissan Leaf has a 40kWh battery and a 100 mile range* (from here). 40 kWh divided by 13 'spare' kWh per household per day = people can recharge their cars every three days. It would have to be staggered; if everybody plugged them in Sunday at midnight, there wouldn't be enough electricity to go round. So instead of Economy 7 electricity, which is cheaper in the night time, there would have to be a massive premium on electricity in the night from Sunday to Monday, or something.

* Check: Electric cars can do 2.9 miles/kWh (from here).

About half of all car miles are commuting, and the average journey (one way) is less than 10 miles, so most of us would be OK for commuting and a weekly shopping trip, with just one overnight charge per week (in a normal week).

Check: Total miles driven in the UK per year (car, van, taxi) = 658 billion km = 409 billion miles.(from here). 100 miles every three days (max capacity, from above) x 28 million households/cars = 340 billion miles/year, so miles driven would have to come down by about a fifth.

So ball park, yes, if we ran power stations 24 hours a day, and reduced overall miles driven (more public transport, more car sharing, work nearer home or from home, don't go on holiday by car, no driving round just for the joy of it* - a problem which solves itself), we could just about manage.

It's still a ridiculous idea, for many other reasons**, but on this narrow point***, I think the idea just about passes the feasibility test.
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* Most of the miles I drive, to be honest.

** Negative impact of CO2 on climate has been exaggerated ten- or a hundred-fold; it will he hugely expensive to upgrade all the transformers and sub-stations in residential areas; there isn't enough copper for the cables or rare metals for the batteries; it will take decades to switch over; the number of people run over will increase because you don't hear them coming; and electric cars are no fun, but hey.

There's also the point that one of the many reasons why fuel duty is such an excellent tax is because it trebles the actual real cost of the fuel (a few pence per mile). Electricity only costs a few pence per mile simply because there is no tax on it (and not because it is inherently cheaper or more resource efficient), and electric cars use hardly any electricity while stationary, so the number of traffic jams might well increase.

*** Judged on its own terms, the exercise is fairly futile. Retail petrol and diesel sales are 37 bn litres/year (with another 9.5 billion litres for commercial, i.e. lorries, construction equipment, trains, tractors, who are definitely not going to go electric). So in theory we could stop burning 37 bn litres of fuel on the road.

If electricity generation goes up 40% and half of that is gas, oil or even coal, we simply use half of that 37 bn in power stations, a net saving of 19 billion litres.

We could achieve much the same reduction by simply moving to hybrid cars (as recommended by Bayard), which can achieve 80 or 90 mpg. They can do 10 - 50 miles on battery alone, so you could turn off the petrol or diesel engine while in town, thus reducing pollution where people live (Mombers' argument in favour of electric cars, about the only valid argument in favour of them IMHO). This requires absolutely no changes to our infrastructure and the shift could happen organically.

That 19 billion litres saved is only a fraction of total fossil fuel usage in the UK. 19 billion litres = 172 TWh, and current gas usage (domestic and power generation) is 869 TWh. Then there's the 9.5 billion litres of commercial diesel = 92 TWh, plus various other bits and pieces. See various charts and tables here.

I'm assuming here for simplicity that CO2 emitted per TWh is approx the same whether you are using gas, petrol, diesel or coal; whether you are using it in a car engine or in a power station to generate the electricity to run the car. On this basis, UK's CO2 emissions would come down by about one-sixth.

Interestingly, UK CO2 emissions have been dropping by a compound average of 1.5% a year since the peak in 1975 and we're already back at the level of 130 years ago (from here), so we'd achieve that one-sixth saving in ten or fifteen years anyway if this trend continues.