On 18/10/2012 19:50, SteveW wrote:
On 17/10/2012 12:10, Doctor Drivel wrote:
tony sayer wrote:
In article , Doctor Drivel invalid@not-
for-mail.invalid scribeth thus

"The Other Mike" wrote in message
...
On Tue, 16 Oct 2012 00:14:26 +0100, "Doctor Drivel"
wrote:

SteveW wrote:

Pure electric vehicles
cannot (may never?) have the energy density and rapid refill
times of the "old" technology.

That is pure nonsense.


Petrol is around 34MJ per litre. A 50 litre refuel takes around 2
minutes

So that is 1700MJ transferred in 2 minutes

1MJ = 0.28 kWh

Or around 476kWh of energy transferred from the petrol station
storage tank to
the car fuel tank in 2 minutes

But 80% of the energy in that tank is wasted. So go back and do
some sums.

Why don't you give us some realistic realisable sums instead?..

I am not the one doing the skewed sums. The average vehicle wastes 80%
of the energy in the tank, negating any energy density claims of the
fuel in running vehicles. The average electric car wastes less than 5%
of the stored energy. There is the clue.

A good diesel is 40% efficient. Some of that 60% loss is useful for
heating. Some goes in rolling resistance, some goes in wind resistance,
etc.

An electric vehicle (on your figure) has 95% efficiency (motor losses),
but then you have to take off rolling resistance and wind resistance,
etc. just as for the diesel.

Take off more for cabin heating and for charging inefficiencies.

Now lets be very kind and say you can actually achieve 85% efficiency.

Of course you need a power supply and a baseload, coal-fired power
station only achieves 40% efficiency.

So your 95% efficient electric car is actually only 34% efficient.

If you use more efficient gas fired stations (50%) you've managed 42.5%

So on average your ev is less efficient than a good diesel, costs much
more to buy, has limited life batteries that will need replacing at
great cost, has limited range and long "refill" times, gives the driver
"range anxiety", suffers the serious pollution aspects of battery
manufacture - shall I go on?

Oh and we've not even allowed for transmission losses!

SteveW

Should there not be an allowance for distribution costs/inefficiencies
of the diesel - if you are including transmission losses for elctricity?
Mind, I have no idea of the likely magnitude of that.

--
Rod