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?..
Because he can't?
I am not the one doing the skewed sums. The average vehicle wastes 80%
Are you not?
of the energy in the tank, negating any energy density claims of the
fuel in running vehicles.
Well no. If the energy density advantage were only 5:1 then you might
have a glimmer of hope - although in reality it would still be wrong for
other obvious reasons.
Since the best battery technologies can't even mange 0.7 kWh / litre,
the ratio is over 50:1.
So even if you go with the lie that the electric system is 100%
efficient, you are still ten times worse off.
The average electric car wastes less than 5%
of the stored energy. There is the clue.
Bwahahahahaha, oh good one, tell us another.
The charging process alone is significantly less than 95% efficient. You
will dissipate significant heat in the battery and the charger, and even
then will never recover 100% of the energy you actually manage to get
into the battery. Then when you use it, you will lose yet more.
All that is after you have had the power delivered to your charging
point. Consider that 10% of that generated was probably lost in
transmission, and it came from a power station that may have been 35%
efficient in the first place, and the whole argument collapses.
Then take into account advances in batteries (Toshiba) and
Batteries may get better - compared to other batteries. They are not
even in the same ballpark as liquid fuels.
See if you can find the battery technologies on this chart:
http://en.wikipedia.org/w/index.php?...ity.svg&page=1
supercapacitors, etc and the IC engines as direct power units become
capacitors are *significantly* worse than the best battery technologies
in terms of energy density. So while they may have uses in some
applications, bulk storage of energy is not one of them.
[snip regurgitation of glossy brochures]
In city driving BMW viewed the kinetic energy would be enough to charge
the battery. A long highway drive would entail the alternator coming in
occasionally - not all the time. BMW said about 4% better fuel economy
from the alternator alone.
To make matters better put in electric power steering and fuel
consumption matters are even better again. Then using a Ni-cad battery
or Lith-Ion battery will mean greater electrical capacity for a smaller
battery package. The fan belts for the water pump and power steering can
be eliminated. Also using an electric a/c compressor will make matters
better too and again another fan belt eliminated. None of this is
rocket science and can be implemented immediately in all cars.
So you want to shift all these loads from being direct powered by the
engine to power them indirectly from the engine?
Implementing electrically powered water pumps, oil pumps, PS
pumps,compressors, etc. do reduce the parasitic draw on an engine.
Erm, where is the electricity coming from?
Look at supercapacitors, as they can claw back 99.99% of the kinetic
energy and give it all back.
You really should engage a bit of thought before making these claims.
How do you convert the kinetic energy into electricity with adequate
efficiency to achieve this?
How do you convert electricity to kinetic energy with adequate
efficiency to achieve this?
The answer is that you can't
You seem to be looking at the efficiency of charge recovery from a
capacitor and assuming that applies to a whole system that is comprised
of many things that are not capacitors.
Buses are running on them in Shanghai. A
No, buses are running on electricity generated by a power station. The
capacitor is a very very short range fuel tank.
Texas company "claims" to have developed a supercapacitor with the same
energy density and size as a normal lead-acid battery.
So even if true, they have developed a capacity with a absolutely crap
energy density compared to a litre of liquid fuel.
That mean the
chemical battery can be replaced.
With something equally crap.
BTW, the Prius was originally to have
a supercapacitor. A combination of supercapacitor and battery may be
implemented soon. They have improved in 15 years.
The way foward is the Vaux Ampera. This setup can be greatly improved by
superior batteries and a smaller more efficeint range extender.
--
Cheers,
John.
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