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Are we on the brink of an electric car revolution?
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emordnilap



Joined: 05 Sep 2007
Posts: 13891
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PostPosted: Wed Aug 02, 2017 12:38 pm    Post subject: Reply with quote

Pepperman wrote:
emordnilap wrote:
Pepperman wrote:
Fair enough. I've never thought that pure EVs are appropriate in all places (although I suspect they are appropriate in 99% of places).


The latest Tesla promises 300km on a charge, which makes it a good car for most people in Ireland. In fact, it'd do for most people in these isles - that'd be a fair whack of driving without a break.


Completely but there's always someone who wants more than that so they'll be catered for in some way. Tesla does achieve great range but it does that using a massive battery which puts it out of reach of most.


They're reasonably priced, considering (though still outside the average reach of course) and there's a 450km version too. Apparently 50 have arrived in the UK so go and test one for us, Pepperman!
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johnhemming2



Joined: 30 Jun 2015
Posts: 1909

PostPosted: Wed Aug 02, 2017 6:06 pm    Post subject: Reply with quote

Pepperman wrote:
Looking at it another way, we have 32m (erk..!) cars on the road at the moment driving about 8000 miles each. Assume 0.3kWh/mile (taking into account charging efficiency) and you've got about 75TWh. For comparison, UK electricity demand is just over 300TWh so electrifying all cars is about 25% of final demand.

This is a good alternate viewpoint.

Using:
http://www.racfoundation.org/motoring-faqs/mobility

Quote:
At the end of March 2017 there were 37.5 million vehicles licensed for use on the roads in Great Britain, of which 31.1 million were cars. In the year to March 2017 the stock of vehicles increased by 2.2 per cent. This is the sixth consecutive quarter that year-on-year increases have exceeded 2 per cent. This also occurred in two quarters of 2014 but had not previously been seen since 2005


The figures I got for national usage almost certainly included all the cars (and probably some electrically powered trains).

Using a bottom up calculation, therefore, would point something over 100TWh.

Electric vehicles do have the potential to provide a material amount of smart storage which can cope with more unpredictable supply.

However, I think the 10% figure is low. It would be good to identify the discrepancy between the national figures and the aggregated bottom up figures. That may arise from a greater comparative efficiency in kWh per mile.

On the other hand it depends upon how many Wh per mile. Looking at the tesla forums it can be as high as 400.

At least we are in the right ballpark on this.
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johnhemming2



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PostPosted: Wed Aug 02, 2017 6:27 pm    Post subject: Reply with quote

Actually I wonder if they included airflight in the transport fuel.
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Pepperman



Joined: 10 Oct 2010
Posts: 758

PostPosted: Thu Aug 03, 2017 9:09 am    Post subject: Reply with quote

johnhemming2 wrote:
However, I think the 10% figure is low. It would be good to identify the discrepancy between the national figures and the aggregated bottom up figures. That may arise from a greater comparative efficiency in kWh per mile.

On the other hand it depends upon how many Wh per mile. Looking at the tesla forums it can be as high as 400.

At least we are in the right ballpark on this.


The 10% figure is based on some % of the fleet being EV (70% of new cars by 2040). Its also based on electricity demand in 2040 which is expected to be higher due to increased electrification of heat. I like to compare it against the current grid as it makes more sense to me. I think both estimates are probably consistent.

Teslas aren't your average EV. There are three EVs (Zoe, i3 and Leaf) which outsell the Model S and all three of those have much lower consumption:

http://www.nextgreencar.com/electric-cars/statistics/
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johnhemming2



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PostPosted: Thu Aug 03, 2017 9:24 am    Post subject: Reply with quote

It has been clear for some time that Electric Vehicles are the way forward. I still think the estimate is low, however.
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Pepperman



Joined: 10 Oct 2010
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PostPosted: Thu Aug 03, 2017 9:53 am    Post subject: Reply with quote

It is still slightly surprising to me that electrifying road transport can be that "easy" (it's not easy, it's a huge amount of electricity, but I think it's considerably less than is generally perceived).

Here is road transport fuel consumption (million tonnes of fuel) in 2015:

Cars 22.40
LGV 5.76
HGV 6.23
Buses 1.18
Motorcycles 0.17

I'm pretty happy with my estimate of 25% of current demand for electrifying cars (I reckon to within +/- 5%), so the above figures suggest it might be another 5%-10% for vans and about the same again for trucks. Rail diesel demand is 1% of total transport demand so will be lost in the noise. I can't see how it can be much more than 50% of current demand.

Vehicle internal combustion engines are only 20% to 25% efficient so the actual energy needed to move the vehicle is only a fifth to a quarter of what is actually consumed. With electric vehicles there are some charging losses (say 10% to 15%) but any conversion losses from the battery to vehicle motion are wrapped up in the kWh/mile value already.

Note that I am obviously ignoring the primary energy inputs that go into the power station but that's ok because we're talking about electricity demand here, not primary energy demand.
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johnhemming2



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PostPosted: Thu Aug 03, 2017 12:13 pm    Post subject: Reply with quote

So 25% for cars, 5-10 (for both vans and trucks say 10-20% in total) 35% - 45%. I had a stab over 100TWh which is over 33%. I would be happy to agree a figure of 40% as there are quite a few other variables that cannot today be predicted.
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emordnilap



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PostPosted: Fri Aug 04, 2017 10:45 am    Post subject: Reply with quote

Quote:
A Shell spokesman told Bloomberg the CEO will get a plug-in Mercedes-Benz S500e in September, while the Chief Financial Officer “already drives a BMW i3 electric car.”


So there you are. And Shell are getting out of tar sands and "into renewables" (and attempting to block the EU's moves to electric cars), though they're big into gas and biofuels.

Source
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johnny



Joined: 15 Aug 2017
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PostPosted: Tue Aug 15, 2017 4:10 pm    Post subject: Reply with quote

emordnilap wrote:
Quote:
A Shell spokesman told Bloomberg the CEO will get a plug-in Mercedes-Benz S500e in September, while the Chief Financial Officer “already drives a BMW i3 electric car.”


So there you are. And Shell are getting out of tar sands and "into renewables" (and attempting to block the EU's moves to electric cars), though they're big into gas and biofuels.

Source


A growing trend. My wife works at a bank, and of the 6 charging stations available for employees who drive electric, 5 are filled, day in and day out.
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emordnilap



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PostPosted: Wed Aug 16, 2017 9:45 am    Post subject: Reply with quote

Welcome johnny.
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Potemkin Villager



Joined: 14 Mar 2006
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PostPosted: Thu Aug 17, 2017 1:08 pm    Post subject: Reply with quote

johnny wrote:

A growing trend. My wife works at a bank, and of the 6 charging stations available for employees who drive electric, 5 are filled, day in and day out.


Welcome Johnny, I wonder have you been lurking for long? Wink

I wonder how many folk at the bank drive to work rather than use public transport and why (I guess it is not in central London) ?
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emordnilap



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PostPosted: Fri Aug 25, 2017 5:20 pm    Post subject: Reply with quote

So it's coming: convoys of lorries driven by one human being. Touted as 'cutting congestion' !!!

This is to divert attention from:

• making more money for haulage companies
• getting rid of up to two thirds pesky drivers, who need paying, the cheeky sods (truck driving was in the most common jobs in 28 US states in 2014)
• the taxpayer is paying for trials
• race to the bottom for remaining lorry drivers
• justification for motorway extension and upgrading (paid for by...)
• less freight by rail
• easy challenge for hackers
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adam2
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Joined: 02 Jul 2007
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PostPosted: Fri Aug 25, 2017 5:47 pm    Post subject: Reply with quote

If I have understood correctly, each HGV will still have a driver to steer, and to take control in an emergency.
The first vehicle will be driven just like any other, but the second and third vehicles will have braking and acceleration under automatic control, controlled by both the lead vehicle and by a distance sensor that maintains a modest gap.
No savings in wages.
The gain is less fuel used, due to the second and third vehicles closely following the one in front, and less road space taken up.

Without any reliance on human reaction times, the following trucks can slow or stop more quickly and thus run much closer together.
If the human driver in the leading vehicle brakes, then the following vehicles brake within a small fraction of a second.

No matter how harsh or gentle the braking of the front vehicle is, the following ones should brake at the same rate and remain the same distance apart.

The main pitfalls are firstly what if the front vehicle makes an almost instant stop by colliding with something, a pile up seems unavoidable in that case.
And secondly, the drivers of the following vehicles have less to do and might have trouble staying alert.

OTOH, few if any human drivers leave enough room to stop if the vehicle in front makes an unexpected stop.
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Little John



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PostPosted: Fri Aug 25, 2017 7:33 pm    Post subject: Reply with quote

This is a preamble to driverless vehicles. You know it and I know it
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johnhemming2



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PostPosted: Fri Aug 25, 2017 8:31 pm    Post subject: Reply with quote

I don't think that is being concealed. I worry about the impact generally of technology.
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