[Pumblechook]

""The electric van seems to cover five times more per KWh than your car""

I am too tired at the mo but that is UTTER nonsense.  If it takes X kWh to cover Y miles for vehicle weight Z it will take that whatever the source of the kWh is in the vehicle.  kWH is simply a measure of energy. 

If a light car can do 400 miles on 150 kWh (I mean useful energy..not calorific)  there is NO way a heavy van can do 100 miles on 24 kWh.   

I don't think even the very small G-Wizz can do 100 miles on 24 kWh. They claim (up to) 48 miles and probably it will be more like 30 if you drive at anything like a decent speed.


http://www.goingreen.co.uk/store


Real owners of electric vehicles have found claimed range to be total fantasy.. they get about 1/3 to 1/2 of the
claimed range.

[Pumblechook]

I think I can see what has gone wrong with your thinking there.  You are taking the calorific energy of the petrol and comparing it with the stored energy in battery as if the stored electricity has come from thin air (grown on trees).  The same calorific to useful energy efficiency will apply in the power station.  You might get slighty better efficiency in a power station but as I had said repeatedly the losses along the way wipe out any advantage.  You will get more mpg out of diesel (say) if used directly in a car than you will if the diesel is used in a distant power station or a home generator. 

A group of us  (including some experienced engineers 50 - 60 years old) have thrashed this out on another talkboard and the conclusion from some was that if there was any efficiency saving with electric cars it was small (only due to modern power stations being more efficient these days).  Some agree with me that they are significantly less efficient.

[teragram]

PumbleChooke, It’s a fair cop guv.!!
Bear with me.
I accept your criticism, I did not account for everything, I was thrown by your reference to KWh in the tank, so I’ve done my sums again with some known data.
Take my car - 65mpg = 14.3 miles per litre
Diesel contains 42MJ/litre or 42/3.6 = 11.7Kwh, so my car does 14.3/11.7 = 1.22mile/KWh.
Accounting for all losses in the electricity supply chain, total input to the battery = 75KWh:-
Generator efficiency = 45%
Three stages of transformation at 97% each
Transmission losses at 7.5%
Charger efficiency at 90% (from my days in fork lift trucks modern high frequency chargers can exceed this).
This results in approx 24KWh in the battery
I don’t think I need to include the DC-AC inverter as this is on-board, ie., part of the motor system.
I have rounded down to avoid overstating my case, in fact large transformers can be 99% efficient. But let’s add a bit to err on the safe side or add an extra transformer, say 80KWh.
This makes the van at 100miles per charge = 100/80 = 1.25miles per KWh, PRETTY WELL A DRAW, but this is carrying it’s battery around, and nearly twice the weight of my car. (with development maybe batteries will become lighter)
Of course the van won’t do anywhere the 700 odd miles my car will on a full “charge”.
I know you don’t believe that electric vehicles achieve their claimed range, I cannot argue, but suspect they would not be dealing with as many of the large companies as mentioned before if they weren’t somewhere near it. We need someone joining in who has some practical experience of using one (I’d be happy to test a Tesla or a Lightning G.T. for a few months).
I would add: My 65mpg is a very respectable figure, not achieved by many cars today (I drive to save fuel). I am retired, so no commuting. Basically, if I did still commute I would expect much less than 65mpg. The cars’ fuel consumption figure is based on a record of it’s mileage and fuel consumption since birth.
Not all of the power generated in the power stations comes from fossil fuel. Some comes from nuclear (low carbon but still bad, and about to start growing) some from wind, even in lagging Great Britain, and this is slowly increasing. The effect on our discussion is that less of the 80KWh comes from carbon producing sources, so the equivalent miles per unit CO2 is less. As more power is generated from non-fossil fuel sources, the battery car will be even better.

[teragram]

P.S., sorry, Pumblechook not Pumblechooke

[Pumblechook]

I think it is very difficult to make comparisons between what are different technologies.  It can get very complicated.

We have been discussing electric vehicles and renewable energy and nuclear on the Guardian Unlimited(newspaper) Talkbord.  I suggest you join.  I am a bit wary about giving you a link..it might sign you in as me.

Google.. Guardian Unlimited Talk

One thread is 'How far are we from a sensible, mass market electric car?'  Science Folder.. 329 posts.  Some threads get 1000s.

One poster agrees with me that a 100 mile range could only be reached with a van if it went pretty slowly.  I have worked out it will do 28 miles at full speed.  Some say that is optimistic.

Pumblechook is a perfect choice because he is a figure from Dickens who is pompous and a know-all.
 

[peppercorn]

I haven't looked through the maths here, but I did notice that the comparisons seem to be based on calculating efficiency of the entire delivery system for a fully charged battery (mentioning heat/mechanical/AC/DC/voltages).

I think it should be pointed out that even though crude oil contains a great deal of potential energy, distilling petroleum fuels from it, plus transporting & storing them goes along way to offsetting that figure in just the same way as talk about the electricity generating network does. -Comparitively, coal has to be dug out of the ground. But it doesn't need to be distilled as well!

To bring us back to Paul's (who started the thread) question:
Electrically powered (by which we mean chemical battery storage) could be infinitely more environmentally sustainable than our current mainstream solutions IF the energy came solely from a renewable resource such as PV solar.

[teragram]

Thanks for the link, Pumblechook. I'm away for a few days, will look at it on return.
Based on you're description of the Dickens character, I could probably out-Pumblechook you!

[teragram]

Interesting points, Peppercorn

[remlapwc]

Perhaps a way round the battery problem on future electric vehicles would be to develop a standard sized slot in battery pack that could be exchanged for a charged pack at the equivalent of a petrol station.