One thing we have learnt this week – electric dreams again

charging point for electric carsElectric dreams again.  The grid is changing and our means of transport is also changing (or at least what powers it).  The problem is a fully electric road system will lead to a big increase in electricity demand.  Possibly as high as 88TWh a year or 8GW at peak demand times.  That’s a lot of electricity, about 25% of what we use now.  Charging all the possible cars will be an issue since the rapid  chargers use a lot of electricity so require a 3 phase supply.  Even if they don’t use rapid charging then demands will be high as in theory everyone comes home in their car and puts it on to trickle charge overnight.  A 50Kw battery is some night-time/evening demand compared with now spread over 8 hours (do the math!).  The easiest way would be to reduce our driving as George Monbiot suggested this week and we wrote about in our book.  Electric cars are not a solution to many of the problems caused by driving.  However as I wrote last week at the moment this seems unlikely.  At the moment as few as 7 cars charging in a neighbourhood could cause a brownout according to the green alliance.

A number of solutions have been proposed.  One obvious one is to combine home battery storage with charging your car.  So during the day when you are out at work your battery system is charged from the solar panels on your roof.  When you get home and plug the car in then this is used to charge your car.  Advantages; less strain on the grid.  Problem you need a pretty big battery system to fill a car and there will be other calls on the batteries as well such as lights/cooking/heating etc.  A major problem of this type of system is winter.  Electricity demand is at its highest when solar production is at its highest.  Nevertheless such an idea will mitigate the grid strain issue to an extent.

The second solution is smart charging and involves the heavy use of smart meters.  When your electricity is cheap then your car would charge.  The problem is many people would overrule this since they would want their car charged this relies on a lower more laid back approach to car use.

The third solution is using the car as grid storage.  The opposite of above.  Your car would be called upon to power the grid when power is short.  The government have see-sawed on their approach to this one.   Ten years ago they were keen on it, then they went off the idea, now they are keen on it.  The advantages are twofold.  With millions of electric cars there will be storage available on a vast scale.  All funded by the consumer.  Second if you could persuade lots of people to forego their cars at any one time then congestion would be less.  The problems are also twofold.  You have to persuade people to do this and to do so will take large amounts of money, pushing up power prices at peak demand times.

In practical terms though grid reinforcement is going to be required on a mammoth scale.  If electric heating takes off and we go totally electric we will need enough generating capacity for about another 800TWh of power a year, an even bigger challenge.


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