Re: Prius seldom runs on batteries alone?

In article <Xns98D9ECFD76CCCjyanikkuanet@64.209.0.86>
[email]jyanik@abuse.gov[/email] "Jim Yanik" writes:
[color=blue]
> [email]ames@deltrak.demon.co.uk[/email] (Andrew Stephenson) wrote in
> news:1171652924snz@deltrak.demon.co.uk:
>[color=green]
> > In article <Xns98D97FF09C921jyanikkuanet@64.209.0.86>
> > [email]jyanik@abuse.gov[/email] "Jim Yanik" writes:
> >[color=darkred]
> >> How about charged from 120VAC line?
> >> When you get home or where an outlet is available.
> >> Then you use cheaper,more efficiently generated mains power for
> >> charging,not expensive gasoline.[/color]
> >
> > The exact numbers are not to hand but, in general, the efficiency
> > of charging from a wall socket is not as good as people generally
> > think. It may be $cheaper to the householder than what is put in
> > in fuel tank; but that's a red herring in the efficiency puzzle.
> >
> > Consider these stages when charging:
> >
> > * burn fuel at the power station and convert to electricity (hard
> > to compute the efficiencies if the energy source is, say, hydro
> > or solar or one of those, so skip them for now);
> >
> > * convey the electricity to wall socket and charger unit (if long
> > journey across country, losses not negligible);
> >
> > * convert electricity to form suitable for battery (low volt DC),
> > then convert to chemical energy, then back to electricity (huge
> > losses overall).
> >
> > Compare this with the clever juggling the full hybrid setup does.
> > Often the battery stays idle, as engine drives generator and that
> > drives electric motor. If it does involve the battery, we do not
> > have to pay for transmission losses. The higher-than-usual Prius
> > petrol engine efficiency... hmm, I'd be guessing irresponsibly if
> > I estimated how it matches up to the power station and would like
> > to know more.
> >
> > Just a thought, right?[/color]
>
> I suspect that electric generation is more efficient any from 120VAC source
> than any hybrid auto,and also outputs far less pollutants.
>
> Transmission losses are present regardless of whether the auto is charged
> from the line or not.Losses from corona discharge/leakage are far greater,I
> suspect.
>
> and you neglect the conversion losses that the auto has in going from
> electric to mechanical and back,also the self-discharge the batery pack
> has.[/color]

I considered listing each last tiny cause of inefficiency I could
imagine then decided to group them, eg: "* convert electricity to
form suitable for battery (low volt DC), then convert to chemical
energy, then back to electricity (huge losses overall)". Leaving
it to technically minded readers to fill in details seemed good.

We need more reliable, clear numbers.
--
Andrew Stephenson