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Discussion Starter · #1 · (Edited)
Most, 90+% of driving miles are within range (well less than 200 miles) of the home parking spot.

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(statistics are for the USA, I suspect that the UK drives shorter distances.)

Proposed: AC charging at 6kW or so at all private parking and roughly 20% of all public parking. At an average yearly use of 8,000 miles (UK average is 7,900) and at 3 miles per kWh, roughly 8000miles/3miles per kwh is needed per year, roughly 2700 kWh per year. Or about 300 Watts of average charging power.

There is roughly 36 million cars in the UK. This would require roughly an average utility supply of 175 W * 36 million or roughly 11 GW average. There would be both a yearly cycle, fewer miles driven in winter but more energy use per mile, a weekly cycle (commuting vs weekend trips) and a daily cycle (charging at home vs charging at work or shopping), so the peak supply needed would be larger than this.

Of course, this is only a 90% solution. Assumes that average range of BEVs will be 200 miles or more. Assumes that public charging parking spots can be billed and otherwise managed so as to avoid bad behavior.
 
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You might want to revisit those numbers - I think your "average consumption per car" of 175W is too low.

But I don't think you are addressing the problem in a useful way: averages are fine if you want to see the impact on total electricity usage, but tell us almost nothing about where we need chargers. Travelling 100 miles a day, if I have a home charger, means I never need to charge away from home. If I travel 400 miles once every four days, that's a very different thing - I'll have to charge away from home every single trip.
 

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You might want to revisit those numbers - I think your "average consumption per car" of 175W is too low.

But I don't think you are addressing the problem in a useful way: averages are fine if you want to see the impact on total electricity usage, but tell us almost nothing about where we need chargers. Travelling 100 miles a day, if I have a home charger, means I never need to charge away from home. If I travel 400 miles once every four days, that's a very different thing - I'll have to charge away from home every single trip.
Yep, as has been pointed out previously on the forum, where to put what charging gets complicated quickly.
 

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Discussion Starter · #4 ·
The other 7% of the solution.

But it is not possible now, because there is not enough capacity, and it is going to be unworkable to install 100 times what there is now for a 100% BEV fleet. That is the issue.
Yet 100 times more isn't what's needed.

Most locations today are single charger or two chargers.

These are very inefficient due to queuing theory.

Assuming random arrival times:
With one charger, if it is in use even 10% of the time, you have a 10% chance of needing to wait, and the average wait will be half of the charge time. So the average charge time is 105% of the usual charge time. Which is simple to compute.

With 100 chargers in use 93% of the time, you have an average wait time of 5%, and the average charge time is 105% of the chance of needing to wait. I used a calculator.

If an average wait of 5% is acceptable, adding 99 chargers to the original single charger adds 1000 times the capacity.


A system wide design might start with noticing the existing distribution of gas pumps. Assuming home/work/hotel charging for almost everyone:

Most of the gas pumps that service local traffic are not needed to be replaced with DC chargers. This is about 95% of the gas pumps. These are often smaller stations, so are less efficient due to queuing theory.

Most of the freeway gas pumps that mostly service long distance travel need to be replaced with more DC chargers. How many more depends on range and charging speed, and don't forget that that a journey that takes n * effective range needs n-1 charging stops.

If the range of an electric car is half of a gas car, and it takes ten times as long to charge as refuel, then less than 20 times as many charging stations are needed as gas pumps for distance travel. And don't forget that larger numbers of charging stations are more efficient due to queuing theory.

Notice that the total number of dc quick charge stations needed is very roughly equal to the number of gas pumps. Might even be less. Might be a bit more. Just distributed much differently.

This is rough back of envelope type calculation, please feel free to suggest improvements. Do notice that electric cars are getting more range, and faster charging.
 

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Discussion Starter · #5 ·
You might want to revisit those numbers - I think your "average consumption per car" of 175W is too low.
Correct. 8000 miles / 3 miles per kWh / 365 days/ 24 hours = 300 watts.

I'll correct the base note.
 
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Discussion Starter · #6 ·
But I don't think you are addressing the problem in a useful way: averages are fine if you want to see the impact on total electricity usage, but tell us almost nothing about where we need chargers. Travelling 100 miles a day, if I have a home charger, means I never need to charge away from home. If I travel 400 miles once every four days, that's a very different thing - I'll have to charge away from home every single trip.
That is the point of the graph. Daily travel longer than 200 miles is rare.
 

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Correct. 8000 miles / 3 miles per kWh / 365 days/ 24 hours = 300 watts.

I'll correct the base note.
The Grid tell us they can cope with the base demand (it was quite a bit higher in the past than it is today, less manufacturing I guess), the problem is peaks in demand and provision of supply from the grid to chargers.

If you buy a Tesla (reasonable range, reasonably efficient, Supercharger network) and you have home charging (cheap, simple, convenient) the switch to EV is straightforward. So all we need is cheaper Teslas, universal home charging, some more Superchargers and it is job done. Involving anyone else is just making it more complicated than it needs to be. :D
 

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Discussion Starter · #8 ·
Yep, as has been pointed out previously on the forum, where to put what charging gets complicated quickly.
The main part, well over half, isn't the slightest bit complicated. It is at home.
 

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Discussion Starter · #9 ·
The Grid tell us they can cope with the base demand (it was quite a bit higher in the past than it is today, less manufacturing I guess), the problem is peaks in demand and provision of supply from the grid to chargers.
So make the chargers or the charging stations smart. Usually the driver doesn't care when the needed two hours of charging are done out of the 14 hours plugged it. Let the grid tell the car/charging station when the grid has excess capacity. Charge then, not when the grid is busy.
 

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So all we need is cheaper Teslas, universal home charging, some more Superchargers and it is job done. Involving anyone else is just making it more complicated than it needs to be. :D
Assuming we live in the Peoples Republic of Elon and everyone ‘has’ to own a Tesla 😁
 
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