Stock Plug In

[timberwolf]

I think you have misunderstood, I'm not attacking electric cars or green issues. I'm only interested in the validity or otherwise of the claim that we wouldn't need to build more electrical generating stations, and that we supposedly have enough already.

I like to think I am logical person, and put as simply as I can, if you remove an energy source (does not matter what it is made of or where it came from), it cannot simply be replaced with what we have left unless there was a massive over capacity in the remaining sources of energy.

[Grumpy Cabbie]

My calculation was wrong I think. I just roughly guessed at 10 miles for 4 kwh. But having read up on the Leaftalk website it appears the 24 kwh Leaf Battery only has a usable proportion of 18.5 kwh. If that takes you 80 miles (not from totally full to totally empty) then I imagine the 4 kwh will take you 17 miles.

For a petrol car burning 2 gallons at 50 mpg, then you could go 34 miles on electric purely on the electric used to refine the petrol, let alone all the other electricity and energy used to make that one gallon.

Not sure about your last paragraph - I might be being thick. But don't electric cars utilse the energy at over 90% efficiency compared to 30-45% in a petrol/diesel car? I always remembered Clarkson mocking that the Battery in a Prius has the same amount of power as a table spoon of petrol and how the audience laughed. What he didn't tell is that because electric propulsion is much more efficient that petrol/diesel, that that equivalent of 1 table spoon of petrol actually takes you much further.

I'm not trying to disagree with you and much of this discussion is for the benefit or questioning of others. I do think oil powered vehicles (petrol & diesel) use a source of fuel that is extremely wasteful at all stages of production. The flares on refineries just seems so wrong to me. Surely surely surely that gas could be put to some other use rather than just burned at source.

At least with electric vehicles there are more options for cleaner electricity generation. Many owners on the Leaf forum use 100% renewable or even nuclear. Some generate it themselves. Ever since that fuel blockade back in 2001 (or thereabouts) I have never liked that feeling of vulnerability attached with using petrol/diesel. Then the greeney in me hates the waste and profits and pollution. There has to be another way.

[Sagitar]

My calculation was wrong I think. I just roughly guessed at 10 miles for 4 kwh. But having read up on the Leaftalk website it appears the 24 kwh Leaf battery only has a usable proportion of 18.5 kwh. If that takes you 80 miles (not from totally full to totally empty) then I imagine the 4 kwh will take you 17 miles.

You're pretty close based upon my experience with the PiP.

A typical "electric only" run for me would be just under 12 miles (say 11.7), while the re-charge consumption will vary between 3.5 and 3.7 kWh. The charge is measured at the meter, so it takes account of all the vagaries of efficiency etc and gives a direct measure of the variable cost of the mileage.

[timberwolf]

My calculation was wrong I think. I just roughly guessed at 10 miles for 4 kwh. But having read up on the Leaftalk website it appears the 24 kwh Leaf battery only has a usable proportion of 18.5 kwh. If that takes you 80 miles (not from totally full to totally empty) then I imagine the 4 kwh will take you 17 miles.

80 miles / 18.5 kWh = 4.3243 miles per kWh

If we save 4.5 kWh by not processing one imperial gallon of petrol then we could travel:

4.3243 miles * 4.5 kWh = 19.45 miles in the Leaf.

How many cars in the UK get less than 19.45 mpg?

(US gallon is smaller than an Imperial gallon and you have to look at cars that can only get up to 16.2 mpg US)

We can do a similar calculation for the Prius Plug-in of 11.7 miles for 3.7 kWh:

14.23 miles (unfortunately the Battery is not large enough to hold 4.5 kWh ?)

If we calculate for a very cold winter the EV range would be reduced?, is 50 miles realistic? Only cars below 12.16 mpg imperial would then qualify (and it being winter petrol/diesel cars mpg reduces as well).

For a petrol car burning 2 gallons at 50 mpg, then you could go 34 miles on electric purely on the electric used to refine the petrol, let alone all the other electricity and energy used to make that one gallon.

Erm, using 2 gallons driving in a 50 mpg car could achieve a distance of up to 100 miles.

Not sure about your last paragraph - I might be being thick. But don't electric cars utilse the energy at over 90% efficiency compared to 30-45% in a petrol/diesel car? I always remembered Clarkson mocking that the battery in a Prius has the same amount of power as a table spoon of petrol and how the audience laughed. What he didn't tell is that because electric propulsion is much more efficient that petrol/diesel, that that equivalent of 1 table spoon of petrol actually takes you much further.

Yes, petrol is not especially efficient but then how efficient is electricity generation?

For anyone still awake, I think I've managed to work out how many kWh there are in a gallon of petrol. According to the following http://en.wikipedia.org/wiki/Energy_density

Petrol/Diesel has approx 36 MJ/litre energy density.

An imperial gallon is therefore:

36 MJ/l * 4.54609 = 163.66 MJ per Imperial Gallon.

1 MJ/l ~ 0.28 kWh.

So one Imperial Gallon of petrol contains:

163.66 MJ/gallon * 0.28 kWh = 45.825 kWh per Imperial Gallon.

(USA 136.27476 MJ/US gallon * 0.28 kWh = 38.157 kWh per US Gallon)

[Sagitar]

I'm not sure where the 4.5 kWh per refined gallon comes from. The figures that I have seen in industry calculations range from 6kWh to more than 12kWh per gallon refined.

Using these figures, the PiP would do about 20 to 40 miles on the energy used to produce a gallon of petrol, but it's all a bit academic and the figures are very speculative. Of course the PiP "electric-only" mileage is only available at speeds up to about 55 mph. It suits me, because the vast majority of my mileage consists of short journeys in a speed restricted urban environment.

Elon Musk has made an art form of propaganda favouring his cars but I wouldn't swallow it all uncritically and we have to distinguish between speculation about the future and what is available now.

Last year I listened to his senior man in the UK doing a lecture at Cranfield. He quoted an enormous range of figures showing that Battery driven cars were the future and I was very impressed. I was also impressed to note that he had driven a long way to get to the (evening) meeting and had chosen not to do the trip in an electric vehicle.

[timberwolf]

The figure came from the video, so yes could be suspect, I assumed they would be exaggerated. Internal figures can be just as misleading, unless you've had access to the confidential version only presented to the board.

You might consider it pointless, but I think it is useful to think about it rather than just accept figures on little more than faith. I might not be able to come up with a ball park figure, but I can begin to see how complex it would be to arrive at an answer, and I wonder at how an electric car maker would be able to come up with the fact and figures.

[Grumpy Cabbie]

But it's also right to question it too.

Nobody can deny the significant sums of electricity consumed and how polluting the 'well to wheel' is. It also brings in significant amounts of money too - for some.