Re: LONDON CABS GOING ELECTRIC

 wrote:


It is due to efficiency.

A car uses less than 1/3 of the potential energy of the fuel for
actual movement.

Electric cars uses more than 90% of the potential enegy for movement.

If electricity is generated at about 50% efficiency, and you have 10%
loss in transmission, and another 10% loss in batteries. Then you got
35-40% efficiency.

Also, an electric car (and hybrids) will regenerate electricity when
you slow down/brake/goes downhill. The effect of this depends on where
and how you drive, but my guess is that you get 10-20% higher
efficiency.

In traditional cars, that energy is converted to heat, either in the
engine or at the brakes

Some of this will be "eaten up" by the heavier weight of the car. I do
not know how much this might be, but if one says 10%, you should still
end up at 40-50% efficiency.

If Generating and transfer efficency goes up, so does the total
efficiency of the car. Hydropower would be ideal, as it has an
efficiensy of 95%

Also remember that if electricity is produced at a big plant, the
excess heat can be used for heating and you may controll/scrub the
emissions.

Not to mention that electricity can be made by many sources, petrol,
more or less, has to be made of oil.

Pricewise, one gallon equals 34 KW of power. Since the price of
electricity is as delivered to your door, and you only have to count
in loss in batteries, added weight and loss at the engine. You should
be well in the clear if you use 70% efficiency from plug to movement.

15KWh of electricity should be more than enough to do the same work as
one gallon of petrol. I do not know how much you pay per KWh, but at
15c/KWh, this turns out to be $2.15

--
SEE YA !!!
Trygve Lillefosse
AKA - Malawi, The Fisher King

  Trygve Lillefosse wrote:

The accepted figure is 36KW, not 15KW.

It is not at all obvious how electric vehicles will reduce carbon
emissions. RAISING them is highly likely.

http://www.tinaja.com/glib/morenrgf.pdf


--
Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
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Don Lancaster wrote:


Very highly likely I expect.

Graham

 

Let's take that number and run with it.

With an efficiency of 33% and 36 KWh/gal, a gallon of gas will give you
about 12 KWh of  "shaft" power.   "Grid" power cost on the order of $.10/KWn
so your gallon of gas will give you the same "shaft power" as, say, $1.20 of
electricity from the grid.

When gas was heading up to $4/gallon the electric cars start "looking good."
But when retail prices get closer to $2/gallon (including TAXES), folks who
look at the numbers decide that for motoring about a gas engine isn't so bad
after all.

For stationary equipment and electric motor lasts a heck of a lot longer
than any kind of IC engine.   But when you take electric motors "on the
road" things change.   The weak link becomes the chain of supply from power
plant to the electric motor.   In cars this means an EXPENSIVE battery with
uncertain dangers but with an expected life of a fraction of the IC engine.

Note that even on the railroads the "electric" trains are most justified
because of the point polution problem than the efficiency.

 wrote:


Petrol will give the same heat as just under 35 KWh of electricity.

But if you want to do anything with that energy, you need to look at
the efficiency.

Of that 35KWh, the petrol engine will at best produce 12 kWh of work
and 23 kWh of heat.

If you use 35 KWh in an electric engine, you get more than 30Kwh of
work and less than 5 kWh of heat.


--
SEE YA !!!
Trygve Lillefosse
AKA - Malawi, The Fisher King