When it comes to converting one form of energy one way to mechanical
work only a Pelton wheel can approach an electric motor's 95+%%
efficiency.

In sharp contrast all single cycle high compression ratio ICE small
enough to be hauled down a road tops off at 40%% efficiency with
vehicle size spark ignition ICE generally running below 30%%. That's a
well tuned engine running on it's "sweet spot" rpm.

Why can't anyone do much about the sorry efficiency of 99.9%% of the
prime movers on the planet?

Far and away the biggest problem comes from the basic thermocycles of
adiabatic engines, i. e., gas turbines (Brayton/Joule/Ericsson I),
diesel (Diesel) and spark ignition (Otto).

The machinery dictates the processes and the shape of the thermocycle
and even the idealized [read: fantasy] adiabatic cycle doesn't fill a
Carnot or other isothermalized parallelogram cycle -- the
thermodynamic limit of heat engines -- very well. Materials
temperature limits reduce the Carnot limit below 100%%, so maybe a
little over 50%% Carnot for most ideal adiabatic cycles.

On Fri, 15 Aug 2008 08:04:21 -0700 (PDT), BretCahill@peoplepc.com
wrote:

BretCahill@peoplepc.com wrote:

One word. Carnot.
http://en.wikipedia.org/wiki/Carnot's_theorem_(thermodynamics)

etc etc. And there's more.

Graham

BretCahill@peoplepc.com wrote:

The Prius uses a 4 stroke Atkinson cycle engine. Like a conventional
Otto engine, the air-fuel mix is optimum. But like a diesel there is no
throttle plate. Not pumping air past a throttle plate is supposed to be
one reason Atkinson has a higher efficiency. The effective compression
ratio (and power) are controlled by intake valve timing.

http://en.wikipedia.org/wiki/Atkinson_cycle

arne't you smart!
peoplepc.com> wrote in message
news:f5554356-f802-4096-9fad-cb1d0e313253@26g2000hsk.googlegroups.com...

John Larkin highNOTlandTHIStechnologyPART.com> wrote:

Power plants that run at much higher efficiency (and much cleaner per
kilowatt of energy produced) than any automobile engine could ever hope
to do.

Really? Do you know of any city in the industrialized world that
*doesn't* have an electricity transportation system already in place?
Storage is somewhat problematic but it seems a safe bet that this is
because efforts at storing it more efficiently have been systematically
shut down.

Good point. Without a turbo or other scheme there is an additional
loss from incomplete expansion.

Bret Cahill

You haven't done much in law or politics have you?

Bret Cahill

"Daniel T." wrote:

Do you know of any built entirely with superconductors to eliminate
all I/R losses? Do you know ANYTHING about electricity, other than not
to stick your tongue in a light socket, the second time?

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The crazy, and the insane.

The first sign of insanity is denying that you're crazy.

BretCahill@peoplepc.com wrote in news:f5554356-f802-4096-9fad-cb1d0e313253@
26g2000hsk.googlegroups.com:

Yup. But the gas/oil/coal-fired power plants needed to generate the
electricty do not. Then you have the line losses transmitting it to point-
of-use.