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Topic Title: electric cars
Topic Summary: just on the news breaking...ban of diesel and petrol by 2040
Created On: 26 July 2017 01:36 pm
Status: Read Only
Linear : Threading : Single : Branch
 electric cars   - psychicwarrior - 26 July 2017 01:36 pm  
 electric cars   - MWalker86 - 26 July 2017 02:41 pm  
 electric cars   - geoffsd - 26 July 2017 03:05 pm  
 electric cars   - MWalker86 - 26 July 2017 03:20 pm  
 electric cars   - davezawadi - 26 July 2017 03:28 pm  
 electric cars   - psychicwarrior - 26 July 2017 03:05 pm  
 electric cars   - geoffsd - 26 July 2017 03:32 pm  
 electric cars   - MWalker86 - 26 July 2017 03:42 pm  
 electric cars   - davezawadi - 26 July 2017 04:29 pm  
 electric cars   - rocknroll - 26 July 2017 04:57 pm  
 electric cars   - mapj1 - 26 July 2017 07:00 pm  
 electric cars   - MWalker86 - 26 July 2017 08:03 pm  
 electric cars   - hertzal123 - 26 July 2017 08:56 pm  
 electric cars   - psychicwarrior - 26 July 2017 09:17 pm  
 electric cars   - mapj1 - 26 July 2017 11:38 pm  
 electric cars   - ebee - 27 July 2017 12:42 am  
 electric cars   - davezawadi - 27 July 2017 09:30 am  
 electric cars   - mapj1 - 27 July 2017 09:51 am  
 electric cars   - davezawadi - 27 July 2017 02:13 pm  
 electric cars   - geoffsd - 27 July 2017 02:53 pm  
 electric cars   - sparkingchip - 29 July 2017 09:23 pm  
 electric cars   - sparkingchip - 29 July 2017 09:36 pm  
 electric cars   - davezawadi - 30 July 2017 08:06 am  
 electric cars   - broadgage - 30 July 2017 09:44 am  
 electric cars   - sparkingchip - 29 July 2017 09:26 pm  
 electric cars   - antric2 - 31 July 2017 09:25 pm  
 electric cars   - potential - 01 August 2017 09:13 am  
 electric cars   - ectophile - 01 August 2017 01:15 pm  
 electric cars   - davezawadi - 01 August 2017 01:32 pm  
 electric cars   - AJJewsbury - 27 July 2017 04:14 pm  
 electric cars   - davezawadi - 27 July 2017 04:29 pm  
 electric cars   - sparkingchip - 27 July 2017 05:23 pm  
 electric cars   - mapj1 - 28 July 2017 12:06 am  
 electric cars   - arg - 28 July 2017 10:17 am  
 electric cars   - Fm - 28 July 2017 10:24 am  
 electric cars   - davezawadi - 28 July 2017 12:13 pm  
 electric cars   - ebee - 28 July 2017 12:35 pm  
 electric cars   - arg - 28 July 2017 04:15 pm  
 electric cars   - Zs - 28 July 2017 07:58 pm  
 electric cars   - rocknroll - 28 July 2017 10:07 pm  
 electric cars   - davezawadi - 29 July 2017 09:45 am  
 electric cars   - sparkingchip - 28 July 2017 01:46 pm  
 electric cars   - psychicwarrior - 29 July 2017 10:24 am  
 electric cars   - AJJewsbury - 29 July 2017 08:45 pm  
 electric cars   - AJJewsbury - 30 July 2017 10:11 am  
 electric cars   - davezawadi - 31 July 2017 07:49 am  
 electric cars   - AJJewsbury - 31 July 2017 09:54 am  
 electric cars   - psychicwarrior - 31 July 2017 10:33 am  
 electric cars   - psychicwarrior - 01 August 2017 01:08 pm  
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 28 July 2017 10:17 am
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arg

Posts: 254
Joined: 18 March 2015

To give you some real numbers to work with:

- A large, heavy, high-performance EV will achieve an average of about 3 miles per kWh in real-world use, including motorway driving
and the need for heating in winter. Smaller/slower ones such as Leaf or Zoe will achieve about 4 miles per kWh.
In both cases you can achieve much better if you try hard (and the official NEDC figures that car manufacturers are required to
publish are, like MPG figures on conventional cars, hopelessly optimistic). But 3-4 miles per kWh is what people actually
get in practice.

- Statistics for car use are here:

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/611304/annual-road-traffic-estimates-2016.pdf

Considering just cars and taxis, there were 252.6 billion miles driven in 2016, or an average of 692 million per day. At 3.5 miles/kWh, that needs 200 GWh/day, or 25GW of extra generation for the 8-hour economy 7 period overnight. That's a lot, but only equivalent to the difference between the evening peak and the current overnight low. Obviously we can't expect the flat-out performance needed for the peak to be sustained 24x7, but just keeping generation going at daytime levels through the night would get us half way there.

Add in light commercials (vans) - 49.1bn miles/yr, 135m miles/day, assume 3miles/kWh (heavier than the cars, but lower average speeds), gives 44GWh/day, another 5GW needed overnight.


In practice, the distribution network is likely to feel the pinch before we run out of generation. Those 252 billion miles were driven by 32 million cars, so an average of 7875 miles/year for each car, or 22 miles/day/car, needing somewhere between 5 and 8 kWh charging each night. Given distribution networks planned at 2kW per house average, that's just about OK if everything is precisely average - but of course it won't be. Although the national average is about 1 car/household, there will obviously be many estates with the majority having 2 cars, balanced by others with low car ownership. Likewise, unless given strong incentives the charging load won't be spread evenly through the night. This is easily solved from a technical perspective (smart metering and automated charging control), but putting together the commercial/regulatory arrangements to make it actually happen is harder.

There's also trade-offs. Most people will buy an EV with a bigger battery than they need for day-to-day use because they sometimes want to drive further (and efforts to persuade people that they could hire a car or whatever for those long journeys have been highly unsuccessful - it seems that people want 200 miles of range to feel comfortable buying an EV, even though the statistics say they are only going to be driving an average of 20-odd miles a day in it). So it would be easy to provide people with a chargepoint with three buttons on it when they plug in: a) "Get me enough charge overnight for my commute tomorrow" b) "I'm going on a trip tomorrow, get me a full charge overnight", c) "The hell with the expense, charge at max speed right now!", with suitable financial incentives. That would help with the generation side of things - allowing more charging to be done on days when there's excess renewables (eg. wind) and less when generation is tight - but does put proportionately more pressure on the distribution side of things.


Finally, on the timescale we are talking about, there's the impact of self-driving cars to consider. In one world view, by 2040 all cars will be self-driving and most of us won't bother to own one - we'll just summon a (self-driving) taxi when we want to go somewhere. That doesn't necessarily make much difference to the total energy required, but does make a big difference to when and where charging is needed. On the one hand, given the state of technology and social changes needed, it would be brave to make plans on the basis this is definitely going to happen; on the other hand, it would be foolish to assume it definitely won't happen.
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