## Re: [evworld] Digest Number 536

Expand Messages
• ... No it doesn t. If a vehicle were 60% efficient and traveled 60 miles on a charge for example, as it became 100% efficient it would go 100 miles. That would
Message 1 of 3 , Jul 31 11:08 AM
• 0 Attachment
Al Zelicoff, MD wrote:

> 5. Yet, the MDI is advertised as being able to travel about 200
> kilometers on an air-charge. Given that it is no more aerodynamic than
> battery powered cars (although it is less weighty) and that electric
> motors are, for all intents and purposes nearly 100% efficient in
> converting on-board energy into movement, this suggests that the MDI is
> 20 to 30 times more efficient yet. That just doesn't make sense.

No it doesn't. If a vehicle were 60% efficient and traveled 60 miles on a
charge for example, as it became 100% efficient it would go 100 miles. That
would mean no heat loss from friction, no aerodynamic drag, or any other
factors, i.e., impossible. Obviously 20 to 30 times more efficient is 20 to
30 times impossible.

There was an electric motor company in China advertising that their motor
was so efficient that it could get several times the range of a conventional
motor. Obviously they were smoking the same stuff. Current electric motors
are 85% efficient or more, meaning that there is very little heat loss. If a
motor were 100% efficient (absolutely impossible since there is always some
friction and other losses) it could go 15% further on a charge. Obviously
range must be increased by carrying more energy not so much through
efficiency gains. A lithium-ion pack can carry many times the energy per
weight and volume of lead acid. That makes sense.

Thanks for doing the energy calculations for compressed air. I've always
thought it was highly suspect, but never took the time to disprove it. I
know that it takes a 6 hp air compressor to run a 1 hp or less air tool and
the compressor can't keep up at that. There is a lot of loss in heat when
the air is compressed too.

A compressed natural gas car can get a 200 mile range using all of the
energy in the gas itself from a 5,000 psi cylinder. A home compressor works
for many hours to reach that pressure. To think you could throw away the
energy in the gas and run 200 kilometers on the pressure is ludicrous.

It's hard to get 200 Wh/mi with an electric car with it's highly efficient
motors. How can one expect to get the same or better efficiency out of a
reciprocating engine. An internal combustion engine is about 13% efficient.

Rick Woodbury Phone: (509) 624-0762
President, Commuter Cars Corporation Toll-free: (800) 468-0944
Doubling the capacity of freeways Fax: (509) 624-1466
Quadrupling the capacity of parking Cellular: (509) 979-1815
Zero to 60 in under 4 seconds
715 E. Sprague Ave., Suite 114 Email: rick@...
Spokane, WA 99202 Web: http://www.commutercars.com
• Rick, et. al.: Lord knows I have to defer to your judgment and other experts in an EV-making discussion. But, with respect, on this more general science
Message 2 of 3 , Jul 31 12:19 PM
• 0 Attachment
Rick, et. al.:

Lord knows I have to defer to your judgment and other experts' in an
EV-making discussion.

But, with respect, on this more general science issue, I want to try
efficiency and mileage. I do not think there is necessarily a
linear relationship between the percentage energy efficiency and
miles per unit energy. My reasoning is something along these lines.

Theoretically, in the ideal, one can get an infinite distance from a
miniscule energy input. "A body in motion stays in motion unless
acted upon by an outside force".

So, if we had an ideal car on a non-friction surface and no
resistance (wind or otherwise), after the original "impetus" of
energy, the car should go forever. The distance traveled would be
infinite.

Now, if we include real-world performance issues of acceleration and
deceleration, wind resistance, etc. then do we come closer to a
linear mathematical correlation between energy efficiency and
mileage?

I don't know the upper limits on mileage per MegaJoule, given
idealized thought experiments or alternatively given some defined
real-world constraints (a certain weight to a vehicle, some internal
friction, acceleration and decelleration, wind resistance, etc.).
when we say "energy efficiency" and relate it to mileage.

It seems to me I have read once or twice articles about college-type
contests where teams shoot for the most awesome mileage they can get
and throw away virtually every other consideration. The speed
traveled, the number of possible passengers, etc. etc... these
factors are all subordinated to mileage. And in those contests I'm
pretty sure the mileage figures attained have been astounding, I
think well into the hundreds of miles per gallon (but I could be
wrong... haven't seen this data for years).

In any event, I'm not sure how I should view this issue of mileage
and energy efficiency.

--- In evworld@yahoogroups.com, Rick Woodbury <rick@c...> wrote:
> Al Zelicoff, MD wrote:
>
> > 5. Yet, the MDI is advertised as being able to travel about 200
> > kilometers on an air-charge. Given that it is no more
aerodynamic than
> > battery powered cars (although it is less weighty) and that
electric
> > motors are, for all intents and purposes nearly 100% efficient in
> > converting on-board energy into movement, this suggests that the
MDI is
> > 20 to 30 times more efficient yet. That just doesn't make sense.
>
> No it doesn't. If a vehicle were 60% efficient and traveled 60
miles on a
> charge for example, as it became 100% efficient it would go 100
miles. That
> would mean no heat loss from friction, no aerodynamic drag, or any
other
> factors, i.e., impossible. Obviously 20 to 30 times more efficient
is 20 to
> 30 times impossible.
>
> There was an electric motor company in China advertising that
their motor
> was so efficient that it could get several times the range of a
conventional
> motor. Obviously they were smoking the same stuff. Current
electric motors
> are 85% efficient or more, meaning that there is very little heat
loss. If a
> motor were 100% efficient (absolutely impossible since there is
always some
> friction and other losses) it could go 15% further on a charge.
Obviously
> range must be increased by carrying more energy not so much through
> efficiency gains. A lithium-ion pack can carry many times the
energy per
> weight and volume of lead acid. That makes sense.
>
> Thanks for doing the energy calculations for compressed air. I've
always
> thought it was highly suspect, but never took the time to disprove
it. I
> know that it takes a 6 hp air compressor to run a 1 hp or less air
tool and
> the compressor can't keep up at that. There is a lot of loss in
heat when
> the air is compressed too.
>
> A compressed natural gas car can get a 200 mile range using all of
the
> energy in the gas itself from a 5,000 psi cylinder. A home
compressor works
> for many hours to reach that pressure. To think you could throw
away the
> energy in the gas and run 200 kilometers on the pressure is
ludicrous.
>
> It's hard to get 200 Wh/mi with an electric car with it's highly
efficient
> motors. How can one expect to get the same or better efficiency
out of a
> reciprocating engine. An internal combustion engine is about 13%
efficient.
>
>
> Rick Woodbury Phone: (509) 624-
0762
> President, Commuter Cars Corporation Toll-free: (800) 468-
0944
> Doubling the capacity of freeways Fax: (509) 624-
1466
> Quadrupling the capacity of parking Cellular: (509) 979-
1815
> Zero to 60 in under 4 seconds
> 715 E. Sprague Ave., Suite 114 Email: rick@c...
> Spokane, WA 99202 Web:
http://www.commutercars.com
• I would have to posit that with energy efficiency as with most endeavors 2 simple rules apply: The 80/20 rule and the logrithmic slope of perfection. With the
Message 3 of 3 , Aug 1, 2004
• 0 Attachment
I would have to posit that with energy efficiency as with most endeavors 2
simple rules apply:
The 80/20 rule and the logrithmic slope of perfection.

With the 80/20 you could say that 80% of energy conversion can be had with
20% of the effort both technological as well as energy input. Whereas the
last 20% of energy conversion nirvana would take 80% of the effort. But of
course as has been pointed out perfect energy conversion is impossible and
this is where the second rule kicks in. As one approaches higher and higher
energy conversion efficiencies the effort to attain such efficiency becomes
logrithmically more difficult and expensive. Resulting in the last tenth of
the last percent effectively requiring an infinity of effort.

With this in mind, economically, one should never attempt to recover the 81%
of any task. The ROI just isn't there. One would be better off finding an
alternative task to attempt, a different conversion mechanism to invest in.

Just a thought,
Dave Cline
-----Original Message-----
From: Rick Woodbury [mailto:rick@...]
Sent: Saturday, July 31, 2004 12:09 PM
To: evworld@yahoogroups.com
Subject: Re: [evworld] Digest Number 536

Al Zelicoff, MD wrote:

> 5. Yet, the MDI is advertised as being able to travel about 200
> kilometers on an air-charge. Given that it is no more aerodynamic than
> battery powered cars (although it is less weighty) and that electric
> motors are, for all intents and purposes nearly 100% efficient in
> converting on-board energy into movement, this suggests that the MDI is
> 20 to 30 times more efficient yet. That just doesn't make sense.

No it doesn't. If a vehicle were 60% efficient and traveled 60 miles on a
charge for example, as it became 100% efficient it would go 100 miles.
That
would mean no heat loss from friction, no aerodynamic drag, or any other
factors, i.e., impossible. Obviously 20 to 30 times more efficient is 20
to
30 times impossible.

There was an electric motor company in China advertising that their motor
was so efficient that it could get several times the range of a
conventional
motor. Obviously they were smoking the same stuff. Current electric motors
are 85% efficient or more, meaning that there is very little heat loss. If
a
motor were 100% efficient (absolutely impossible since there is always
some
friction and other losses) it could go 15% further on a charge. Obviously
range must be increased by carrying more energy not so much through
efficiency gains. A lithium-ion pack can carry many times the energy per
weight and volume of lead acid. That makes sense.

Thanks for doing the energy calculations for compressed air. I've always
thought it was highly suspect, but never took the time to disprove it. I
know that it takes a 6 hp air compressor to run a 1 hp or less air tool
and
the compressor can't keep up at that. There is a lot of loss in heat when
the air is compressed too.

A compressed natural gas car can get a 200 mile range using all of the
energy in the gas itself from a 5,000 psi cylinder. A home compressor
works
for many hours to reach that pressure. To think you could throw away the
energy in the gas and run 200 kilometers on the pressure is ludicrous.

It's hard to get 200 Wh/mi with an electric car with it's highly efficient
motors. How can one expect to get the same or better efficiency out of a
reciprocating engine. An internal combustion engine is about 13%
efficient.

Rick Woodbury Phone: (509) 624-0762
President, Commuter Cars Corporation Toll-free: (800) 468-0944
Doubling the capacity of freeways Fax: (509) 624-1466
Quadrupling the capacity of parking Cellular: (509) 979-1815
Zero to 60 in under 4 seconds
715 E. Sprague Ave., Suite 114 Email: rick@...
Spokane, WA 99202 Web: http://www.commutercars.com

----------------------------------------------------------------------------
--