Electric Car? How about a Compressed Air Car?

On 21 Nov 2007 01:06:18 GMT, James Robinson wrote in
:

[snip]

Thank you for providing the information upon which your opinions are
based. It's refreshing to get the opinions on electrical vehicles of
a professional electrical engineer. Thank you for your contributions
to the debate.

I got pretty cynical about claims of energy saving after listening to all
the people who came to our company trying to sell various products that
guaranteed huge energy savings or emission reduction.

There are the snake oil salesmen who have the magic potion that can be
added to the fuel tank to virtually eliminate air pollution, plus it will
double engine life as a side benefit. I wonder why GM hasn't heard of
them? The people with a black box you simply have to hook up to the fuel
line that will absolutely, for sure, pay for itself in fuel savings many
times over, but they won't tell us what's inside it, or how it works,
because it's a company secret. You can trust us; The people who have
special ceramic magnets that can be put on either side of the fuel line
near the engine to align the fuel molecules so they will pass through the
injectors more easily, and therefore burn more efficiently; the people
who resurrect old ideas like water injection, without realizing why it
worked to increase power, but also why it won't improve fuel consumption;
I remember one person who claimed that when he applied his device to an
engine, the horsepower jumped by 20 percent, and he had dynamometer test
results to prove it. The only thing was that when he fudged the figures,
he forgot that RPM times torque equals Horsepower. The horsepower
certainly showed a jump in his test results, but when there was no
associated change in torque or RPM, it completely blew his credibility.
etc. etc. etc.

A new salesman with a new twist would appear at our door about once a
month, so we got lots of practice. It was sometimes really difficult to
keep a straight face during their presentation. After listening to their
pitch, our usual approach was to tell them to go to one of the reliable
engine testing labs and do a standardized test, and if the product worked
as claimed, we would buy all they could sell. We'd never see them again,
but some would even protest that we wouldn't see any improvement by
performing the tests, since the tests were wrong, and we should trust
their claims instead.

Just like the salesmen and women would appeared at our door, I just say
you can trust my calculations.

Ah. This explains your apparent cynicism.

So, let me see if I understand your position correctly. You believe,
that from a physics viewpoint energy recovery through regenerative
braking is marginally useful at best, that the current state of
technology cannot enable the production of useful electric vehicles,
and the emerging popularity of hybrid automobiles is just a vogue
based on marketing prowess? How far did I miss the mark?

[snip additional reasonable explanations]

and in heavy braking it
might be 10 times that required for acceleration. Consider that an
energy-efficient car might do zero to 60 in say 20 seconds, but is
able to stop from 60 mph in less than two seconds.

The prototype electric Mini Cooper and Tesla Roadster mentioned in
these links seem to do 0 to 60 mph in ~4 seconds:

http://www.teslamotors.com/performan...and_torque.php
The Tesla Roadster’s specs illustrate what it does (0 to 60 mph in
under 4 seconds)...

http://www.gizmag.com/go/6104/1/
In the MINI QED, this package offers a 0-60mph time of 3.7 seconds
and a 150mph top speed ...

Yes, that is true. However, they aren't selling those vehicles as
energy-efficient replacements for gasoline powered cars, any more than
Ferrari is trying to sell their cars for commuting.

While that may be true of the MINI QED (it's a prototype after all),
the Tesla Roadster IS being marketed as "high mileage" (as in MPG
presumably), as is apparent from the graph he

http://www.teslamotors.com/performan...tric_power.php
No More Tradeoffs
Up until now, if you wanted a car with amazing gas mileage, you’d
pick something like the leading hybrid; but when you pressed down
the gas pedal to zip up a freeway on-ramp, you'd likely be a
little disappointed — it takes over 10 seconds to reach 60 miles
per hour. On the other hand, if you demanded the 0 to 60 times of
a $300,000 supercar, you'd wind up with an embarrassing 9 miles to
the gallon in the city.

The graph below shows the Tesla Roadster (upper right) in a class
by itself with better acceleration than a Lamborghini Murcielago
and twice the mile-per-gallon equivalent of popular hybrids. The
highly efficient Tesla Roadster gets the equivalent of 135 miles
per gallon with an enviable 0 to 60 time of less than four
seconds.

And if the GM Volt (solely electrical propulsion) ever materializes,
it is also being marketed as "energy-efficient replacements for
gasoline powered cars" with "responsive acceleration" as stated he

http://www.greencarcongress.com/2007...evrolet-v.html
Comparing the fuel costs between old and new methods of
propulsion, GM estimated that driving costs in EV mode would be 2
cents per mile&mash;or 1 cent per mile if charged
off-peak—compared to about 12 cents per mile per gallon of
gasoline for a typical car today.

[snip]

The designer of a vehicle knows that the cost of the motor and control
system varies in about direct proportion to the power to be handled.
He would have to determine whether it would be economically reasonable
to provide a motor that is ten times the size and cost needed for
acceleration just to capture all of the small amount of braking energy
available.

That statement reveals a fundamental misunderstanding. While it may
be true that the active semiconductors may need to be sized for the
peak current, that reasoning is inappropriate for the motor and
conductors.

Yes, motors and conductors can be overloaded for a period of time. I am
well aware of short time ratings, since we rely on those on the machinery
in my business. My assumption is that they would normally be sized in a
car for typical acceleration and the power demand at constant speed to be
economic. The need to collect power at a minimum of ten times those
values suggests that they would have to be upsized to handle the power of
regeneration. There is no free lunch.

But there is a liquid cooling system designed in both the Tesla
Roadster, and the GM Volt, so "upsizing" may not be necessary.

For a real-world example, look at the current hybrids. They use
friction brakes at highway speeds, and do not recover braking energy
regeneratively,

Where did you get that idea?

http://www.toyota.com/prius/specs.html
Brakes Power-assisted ventilated front disc/rear drum with
Anti-lock Brake System (ABS) and integrated regenerative braking

Maybe I should have said that they primarily use friction brakes, with a
minor contribution to regeneration.

I'm unable to provide any research about the percentage of energy
recovery achieved through regenerative braking, but it appears to
theoretically very doable given the fact that the MINI QED is not
equipped with friction brakes at all, and solely relies on
regenerative breaking for deceleration; it needs to be chocked when
parked!

Otherwise, why are ventilated disc brakes even necessary?

I could speculate: For consumer acceptance. To meet government
standards. Lack of imagination. ...

My understanding is that the vast majority of
braking power at highway speeds is dissipated as heat, rather than being
recovered as energy.

Are you able to provide any evidence of the validity of that
understanding?

On Tue, 20 Nov 2007 20:50:55 -0500, "Roger (K8RI)"
wrote in
:

As has been publicized, we don't have the grid capacity to support
much in the way of all electric cars. The same is true for Hydrogen.
It's either produced from fossil fuels with a lot of polluting
byproducts or takes a whale of a lot of electrical energy to produce
from water.

When/if worldwide photovoltaic production ever meets consumer demand,
you are going to see an enormous increase in solar power
installations, not only in commercial buildings, but residences as
well. Today, the excess electricity generated by a home's
photovoltaic power generating system is used to turn the electric
utility meter backwards. As electrically powered vehicles become more
mainstream, that excess solar power could be used to directly charge
vehicle batteries or for hydro-electrolysis to generate hydrogen gas
for fuel.

Side benefits of residential solar power generation are the peace of
mind inherent in the redundancy of distributed (as opposed to central)
power generation and the resulting robustness against massive power
outages due to a cascade of equipment outages triggered by a
single-source failure, the ability to "thumb the eye" of oil
robber-barons, the reduction in the production of pollutants,
insurance against the inevitable increases in the price of energy, and
virtue of abandoning 19th century technology for a more enlightened
solution.

Alcohol is an interim solution with the hybrid being by far the most
economical and quickest to implement of the interim solutions.

As for grid capacity we are rapidly coming to the point of real time
usage monitoring with remote setback of heating and air conditioning.
Here with peak rates of about 10 cents per KWH we wouldn't see the
savings of those fortunate souls paying 38 cents during peak demand
out in the Republik of Kalafornia.

OTOH solar panels don't do us much good either.

Why? Photovoltaic panels are able to convert infrared isolation even
on cloudy days.

On Wed, 21 Nov 2007 17:39:17 GMT, Larry Dighera
wrote:


When/if worldwide photovoltaic production ever meets consumer demand,
you are going to see an enormous increase in solar power
installations, not only in commercial buildings, but residences as
well. Today, the excess electricity generated by a home's
photovoltaic power generating system is used to turn the electric
utility meter backwards. As electrically powered vehicles become more
mainstream, that excess solar power could be used to directly charge
vehicle batteries or for hydro-electrolysis to generate hydrogen gas
for fuel.

I know of two local wind generators that have been trying to "sell"
electricity back for well over two years. One was given permission to
connect to "the grid" and was instructed to disconnect it the next
day.

The current hold-up is that the state public utilities commision is
having difficulty establishing a "fair price". It is obviously not
going to be a case of "turn"ing "the electric utility meter
backwards".

Perhaps there are states where this is happening, but it isn't
happening around here...

TC

"Larry Dighera" wrote in message
...
....

So, let me see if I understand your position correctly. You believe,
that from a physics viewpoint energy recovery through regenerative
braking is marginally useful at best,

Many (most, all?) hybrid vehicles currently in production use regerative
braking. The effectiveness of the regenerative braking is limited by the
fact that the electric drive system is typically not connected to all the
wheels and the maximum current limits in the motor (working as a generator),
electronics, and battery charging capacities. As a result current hybrid
vehicles employ friction brakes along with the regenerative braking to make
up whatever additional capacity is required. Getting the two brake systems
to play well and not change the relation betweeen pedal effort and braking
result takes a bit of engineering...

I don't have the numbers in front of me, but in urban driving a significant
portion of the gasoline energy is expended by the brakes (10-15%? - I used
to have a chart on the wall at my desk, but I don't remember the numbers -
sorry)


that the current state of
technology cannot enable the production of useful electric vehicles,

Define useful.

and the emerging popularity of hybrid automobiles is just a vogue
based on marketing prowess?

Small diesels give about the same fuel economy as hybrids, but the
diffuculty is making the tailpipe emission standards in the US -
particularly California. Thus the popularity of hybrids in the US but not in
Europe where emission standards are easier.

...

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

On Wed, 21 Nov 2007 21:31:45 GMT, wrote in
:

On Wed, 21 Nov 2007 17:39:17 GMT, Larry Dighera
wrote:


When/if worldwide photovoltaic production ever meets consumer demand,
you are going to see an enormous increase in solar power
installations, not only in commercial buildings, but residences as
well. Today, the excess electricity generated by a home's
photovoltaic power generating system is used to turn the electric
utility meter backwards. As electrically powered vehicles become more
mainstream, that excess solar power could be used to directly charge
vehicle batteries or for hydro-electrolysis to generate hydrogen gas
for fuel.

I know of two local wind generators that have been trying to "sell"
electricity back for well over two years. One was given permission to
connect to "the grid" and was instructed to disconnect it the next
day.

The current hold-up is that the state public utilities commision is
having difficulty establishing a "fair price". It is obviously not
going to be a case of "turn"ing "the electric utility meter
backwards".

Perhaps there are states where this is happening, but it isn't
happening around here...

TC

I'm in southern California, and solar residences have been running
their electric meters backwards for several years.

http://www.sce.com/Feature/Archive/2...workssolar.htm
A metering arrangement available from SCE permits extra
electricity generated and not used during the day to be credited
to the customer's account.


http://www.solar-tec.com/CAStateSolarRebate.htm
When the sun shines, you can generate more power than your home is
consuming and your electric meter will spin backwards generating a
credit.





Where are you located?

On Wed, 21 Nov 2007 22:18:24 GMT, Larry Dighera
wrote:

I'm in southern California, and solar residences have been running
their electric meters backwards for several years.

http://www.sce.com/Feature/Archive/2...workssolar.htm
A metering arrangement available from SCE permits extra
electricity generated and not used during the day to be credited
to the customer's account.


http://www.solar-tec.com/CAStateSolarRebate.htm
When the sun shines, you can generate more power than your home is
consuming and your electric meter will spin backwards generating a
credit.





Where are you located?


East of the Mississippi.

IMHO, it would be a little different if there were sound
technical/safety reasoning behind not letting them connect.

TC

"Roger (K8RI)" wrote in message
...
On Tue, 20 Nov 2007 10:27:27 -0800 (PST), Denny
wrote:

...
The electricity has to come from some where and about 2/3rds to 3/4
comes from coal fired plants. These plants put huge amounts of CO2,
Mercury, and Sulphur into the air along with lots of particulate
matter. That means the so called clean electric car would probably
cause far more pollution than what's on the road now.

Both Hydrogen and Electric cars which are touted as being so clean
only move the source of pollution from the vehicle to the power
generation plant. Hydrogen takes even more energy to produce so it is
even less efficient.
...

Prof. Heywood at MIT Sloan Labs has co-authored a few papers on this sort of
topic that you can find somewhere on the MIT website. There is a lot of hype
and nonsense printed out there, but John has always seemed to be pretty
level headed to me.

Aviation content - if it wasn't for his glasses (about 3/8 inch thick) John
Heywood would look kinda like Bob Hoover.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

Saw a program on the History Channel last week about modern oil recovery
technology. They pump CO2 into the well, which releases the crude oil from
the shale and they recover something like three times the previous amounts.

Where do they get the CO2, from capturing the exhaust from the local oil and
coal fired powerplants.

Sounds like a good idea.

Recycle the CO2.

Years ago the University of Illinois at Urbana put dry ice in corn fields
and increased corn production, air born fertilizer.



"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in message
...
| "Roger (K8RI)" wrote in message
| ...
| On Tue, 20 Nov 2007 10:27:27 -0800 (PST), Denny
| wrote:
|
| ...
| The electricity has to come from some where and about 2/3rds to 3/4
| comes from coal fired plants. These plants put huge amounts of CO2,
| Mercury, and Sulphur into the air along with lots of particulate
| matter. That means the so called clean electric car would probably
| cause far more pollution than what's on the road now.
|
| Both Hydrogen and Electric cars which are touted as being so clean
| only move the source of pollution from the vehicle to the power
| generation plant. Hydrogen takes even more energy to produce so it is
| even less efficient.
| ...
|
| Prof. Heywood at MIT Sloan Labs has co-authored a few papers on this sort
of
| topic that you can find somewhere on the MIT website. There is a lot of
hype
| and nonsense printed out there, but John has always seemed to be pretty
| level headed to me.
|
| Aviation content - if it wasn't for his glasses (about 3/8 inch thick)
John
| Heywood would look kinda like Bob Hoover.
|
| --
| Geoff
| The Sea Hawk at Wow Way d0t Com
| remove spaces and make the obvious substitutions to reply by mail
| When immigration is outlawed, only outlaws will immigrate.
|
|

Larry Dighera wrote:

James Robinson wrote:

[snip]

It's refreshing to get the opinions on electrical vehicles of
a professional electrical engineer.

I'm more of a mechanical engineer.

I got pretty cynical about claims of energy saving after listening to
all the people who came to our company trying to sell various products
that guaranteed huge energy savings or emission reduction.

Ah. This explains your apparent cynicism.

I prefer to consider it healthy skepticism.

The problem with many of the proposals for alternative energy sources or
new sources of power for transportation is that while the basic physics
is often sound, the benefits are too often exaggerated, the full costs
are not included, or the downsides are not explained. Sometimes even the
physics is not correct.

Often this comes from enthusiasm in trying something new. People
typically want to believe that there are alternatives, particularly if
they themselves have already spent several thousand dollars on the
technology. Sometimes it is hype to attract money for a project, or to
gain political support. On occasion it is plain deceit.

Because of the above, one needs to at least make a first pass through
some ballpark numbers to see if any claims being made for breakthrough
technology are realistic. If they seem to be a big departure from what
is currently known about the subject, then alarm bells should ring to
indicate that things might be too good to be true.

It is not always easy to find good information, however, particularly if
one doesn't understand the technology. It can also be a problem deciding
if a new technology is all it is described without some history of use.
You can't dismiss it out of hand, nor can you confidently assume it will
work as advertised. That's where the skepticism needs to come in.

So, let me see if I understand your position correctly. You believe,
that from a physics viewpoint energy recovery through regenerative
braking is marginally useful at best, that the current state of
technology cannot enable the production of useful electric vehicles,
and the emerging popularity of hybrid automobiles is just a vogue
based on marketing prowess? How far did I miss the mark?

Yes, no, perhaps, in that order.

It is simple enough to work through the calculations on regenerative
braking to see that while it does provide some savings, and is somewhat
easy to implement in the control system, it does not have a huge effect
on the economics of hybrids.

The question of whether hybrids are useful depends on what considers
useful. If an economic case has to be made, then hybrids are pretty
marginal, or even uneconomic, as Consumer Reports, for one, calculated.
That doesn't mean that the technology doesn't work, just that one
shouldn't expect a return on the additional investment. There might be
better technologies, such as turbo diesels, which are popular in Europe.

Many of the encouraging economics for hybrids early on benefitted from
subsidies provided by various levels of government. Once those subsidies
disappeared, then the economics became pretty strained.

That said, as the development of the technology continues, and
improvements are made, then the economics will also improve. It doesn't
appear, though, that with the developments now being anticipated, that
the economics will ever be breathtaking.

It reminds me of a recent news item where an inventor demonstrated how he
could ignite seawater with radio waves. He was proclaiming that it was a
possible energy source for the future. Well, what he was doing was
splitting up the oxygen and hydrogen in the water, which takes a huge
amount of energy, and the two would then catch fire. In short, the
technology might work, but the economics would be hopeless. Is it a
useful technology? maybe there is some use, but not as an alternative
energy source.

So, is the enthusiasm for hybrids a flash in the pan? Perhaps. You will
note that most auto manufacturers have not jumped on the bandwagon and
built their own hybrid designs. The Germans, as an example, seem to feel
that diesels or plug-in cars are the way of the future to help reduce
greenhouse gases or improve efficiency. Are they wrong?

The graph below shows the Tesla Roadster (upper right) in a class
by itself with better acceleration than a Lamborghini Murcielago
and twice the mile-per-gallon equivalent of popular hybrids. The
highly efficient Tesla Roadster gets the equivalent of 135 miles
per gallon with an enviable 0 to 60 time of less than four
seconds.

Sorry, but when I see claims of 135 mpg for a high performance car, when
the equivalent gasoline-powered car would only get maybe 10 or 15, my
skeptic alarm bells start to ring. It takes a certain amount of energy to
accelerate a car, and there is no magic way of avoiding it. The only
difference might be in efficiency, but there isn't enough room for
improvement for their claims to be realistic. Their claims are simply too
good to be true.

And if the GM Volt (solely electrical propulsion) ever materializes,
it is also being marketed as "energy-efficient replacements for
gasoline powered cars" with "responsive acceleration" as stated he

http://www.greencarcongress.com/2007...evrolet-v.html
Comparing the fuel costs between old and new methods of
propulsion, GM estimated that driving costs in EV mode would be 2
cents per mile&mash;or 1 cent per mile if charged
off-peak—compared to about 12 cents per mile per gallon of
gasoline for a typical car today.

As I wrote earlier, the claims of 1 to 2 cents per mile just aren't
realistic. Don't you wonder why GM wasn't able to get their earlier
electric car effort to pay off? There hasn't been any major breakthrough
that will significantly change things.

As far as acceleration, which is what this discussion was about, consider
that the Toyota RAV4-EV took 18 seconds to get from 0 to 60 mph. If it
was so easy to make a car that does it in less than 1/4 of the time, why
was Toyota's engineering so conservative. I suspect it was because of the
poor economics. Obviously, Tesla isn't that concerned about economics
with a $100,000 car, and is delivering performance for the price.

Yes, motors and conductors can be overloaded for a period of time. My
assumption is that they would normally be sized in a car for typical
acceleration and the power demand at constant speed to be economic.

But there is a liquid cooling system designed in both the Tesla
Roadster, and the GM Volt, so "upsizing" may not be necessary.

That introduces extra cost and complexity into the system. I wonder what
that does to the economics and reliability? Overall, if the vehicle is
designed to accelerate at a rate closer to the typical braking rate, then
my concerns about motor size would disappear. But improved performance
also implies lower economy.

I'm unable to provide any research about the percentage of energy
recovery achieved through regenerative braking, but it appears to
theoretically very doable given the fact that the MINI QED is not
equipped with friction brakes at all, and solely relies on
regenerative breaking for deceleration; it needs to be chocked when
parked!

Otherwise, why are ventilated disc brakes even necessary?

I could speculate: For consumer acceptance. To meet government
standards. Lack of imagination. ...

Well, according to information from Toyota, the batteries will only
accept energy up to a maximum rate of 20 kWh (sic) That's obviously a
misprint, since kW is a rate, and kWh is a quantity. They meant 20 kW.

http://techno-fandom.org/~hobbit/car...s-section6.pdf

Converting that to more familiar units, that works out to 26.8
horsepower. So, the regenerative system can only accept braking energy
at the rate of 27 horsepower. Now compare that to the typical horsepower
of an engine needed to accelerate a car from 0 to 60 in 5 seconds. It
looks like a ten to one ratio, which was my earlier guess.

I also note in the above Toyota document that they claim only 30 percent
of the braking energy is recovered. They don't go into enough detail to
know whether that is simply an average number in typical driving, or if
that is the recovery rate of the charge/discharge cycle, which would mean
an even lower percentage of total energy.

There are a couple of additional features of the regeneration system on
the Prius contained in the following discussion forum:

http://www.techno-fandom.org/~hobbit/cars/b-mode.html

It says that once the batteries are 80% charged, that no additional
energy will be accepted from the regen system. It also says that the
regen system does not work below about 7 mph due to low voltage. (there
wouldn't be much energy to recover at those low speeds in any event)

My understanding is that the vast majority of
braking power at highway speeds is dissipated as heat, rather than
being recovered as energy.

Are you able to provide any evidence of the validity of that
understanding?

I wasn't able to find a cite in a quick search, but there is lots of
documentation out there, so with a diligent search one might find
something.

However, given the info above, one can make a stab at how much energy
might be recovered.

When I drive, I typically apply the brakes such that my car decelerates
at the moderate rate of about 4 to 6 miles per hour per second. Others
might be more or less aggressive, depending on the driving situation and
their patience, but it puts things into the ballpark. A panic stop could
be up to about 20 mphps.

Now let's compare the maximum braking rate, given the weight of the car,
and the limit of 27 horsepower in braking, as a comparison.

The deceleration limit to take full advantage of regeneration at various
speeds would be:

60 mph 1.8 mphps
40 mph 2.7 mphps
20 mph 5.4 mphps

If 5 mphps is the typical deceleration rate, then an shortfall in the
above would be made up by the friction brakes on the car, effectively
converting that portion of the braking energy to heat, which is lost.

So, if I apply the brakes at 60 mph to get a 5 mphps deceleration rate,
then on a Prius, I would be capturing (1.8)/5 or about 1/3 of the
available energy in braking. At 40, it would be about 1/2 of the
available energy, and below about 20 mph, I would be able to capture all
of the energy, until the system dropped out at 7 mph.

Given that most of the energy to be recovered is at high speeds, then the
above suggests that if I drove the car, I would only recover between 1/3
and 1/2 of the available braking energy.

If someone less aggressive drives the car and has a very light touch on
the brake pedal, they might be able to capture a good proportion of the
energy.

In any event, as I suspected, the amount of energy that can be recovered
from the regenerative braking system is limited. You also have to take
into account the efficiency losses in the charge/discharge cycle, meaning
that even less of the recovered energy can be used on the power side.

On Nov 19, 7:25 pm, "Morgans" wrote:
"William Hung" wrote

http://youtube.com/watch?v=QmqpGZv0YT4

More vaporware.

I particularly got a big kick out of the part where the hybrid gasoline air
power car could drive coast to coast of the US on one tank full of petrol.

How dumb do they think we are?

I would be ashamed to be lumped into the masses of people that think it
would be possible, even for a second.

Either that, or it is a VERY big tank full of petrol.
--
Jim in NC

Perhaps, but it seems they are trying it out as TAXIs in India. We'll
see how that goes I suppose.

Wil