[All] IEEE Spectrum: Deflating the Air Car (Skeptics aren't always right!)
Robert Milligan
mill at continuum.org
Tue Jul 13 01:01:43 EDT 2010
ADVERTISEMENT
MAGAZINE MULTIMEDIA BLOGS SPECIAL REPORTS NEWSLETTERS WEBINARS
WHITEPAPERS RSS
ADVERTISEMENT
High temperature potential of flip chip assemblies for automotive
applications
Flip chip technology has been widely accepted within microelectronics
as a technology for maximum miniaturization. Typical applications
today are mobile …
Automotive electronics system, software, and local area network
In this tutorial, an overview of automotive electronic systems and
details of the development methodologies are presented. Automobiles
were born …
The Necessity of Life Insurance in Today's Economic…
Available Now. …
Enabling Electronics for Smart Grid Technologies &…
Available…
Powerful Data Capture Solutions
June 2009 Available on…
Top 10 Clean Energy Business Opportunities
Available Now. IEEE Spectrum presents Build a Better…
A First Look at COMSOL Multiphysics Version 4.0
Available Now. A First Look at COMSOL Multiphysics…
Alt Text
Alt Text
Alt Text
FIXING THE GULF OIL LEAK: BLOWOUT PREVENTERS AND ROBOTIC SUBMARINES
Fri, April 30, 2010
Technology failures that led to the huge spill, …
COMMENTS: 138
FREE THE RADIO SPECTRUM
June 2010
Antiquated regulations have made radio spectrum artific…
COMMENTS: 16
RIGHT TO REPAIR YOUR CAR CLOSER IN MASSACHUSETTS?
Wed, July 07, 2010
State Senate Pass Bill Without Opposition
COMMENTS: 16
CONSUMER ELECTRONICS: 06.30.2010
Building the Lego Universe Online
Lego tries to construct a new empire with …
ENERGY: 07.02.2010
Russia Launches Floating Nuclear Power Plant
It generates 70 MW and plenty of concern
TELECOM: 07.08.2010
NSA To Monitor Critical Computer Networks
Looking for Glaring Security Holes in US Critical…
climate climate change electricity energy environment natural gas
nuclear power policy power renewables solar power wind power
AT WORK: 03.31.2010
Japan's Patent Power
The United States is still the world leader in patents…
COMPUTING: 01.29.2010
Toyota's Sudden Acceleration Problems: What Did It Know…
The US Congress (and Numerous Lawyers) Intends to Find…
COMPUTING: 02.03.2010
US Regulators to Toyota: We're Not Finished With You…
Toyota Spinning Its Wheels
COMPUTING: 02.02.2010
Toyota's Sudden Unintended Acceleration Caused in Part…
Electrical Engineering Professor Says It's Possible
COMPUTING: 01.22.2010
Toyota Admits Another Pedal Problem
Recalls an Additional 2.3 Million Cars
Energy // Environment
FEATURE
Deflating the Air Car
Green cars could run on compressed air instead of batteries. But don't
rely on the new AirPod minicars to prove it
PAGE 12345 // VIEW ALL
Photo: Vincent Lignier
BY PETER FAIRLEY // NOVEMBER 2009
A new celebrity with a lusciously curved body is turning heads on
France’s Côte d’Azur. No, not that kind of body. This one belongs to
the AirPod, a 220-kilogram car with a sculpted composite shell and a
back-to-the-future energy supply: 80 kg of air compressed to 350 times
sea-level atmospheric pressure, roughly 350 bars. The engine of this
tiny three-seater converts that air into mechanical energy, just as a
pneumatic jackhammer does to blast apart concrete.
The AirPod won’t exactly tear up the road, though: The current version
tops out at 45 kilometers per hour (28 miles per hour). And yet
there’s definitely something addictive in its joystick steering and
featherlike suspension. With expanding air pumping its pistons, the
exhaust is literally a superchilled breeze. Grab the stick, step on
the accelerator, and any guilt you may be harboring from driving an
ordinary smog-producing carbon spewer falls away. Wouldn’t life be
great if everybody got around town in these clean little machines?
This rosy vision of future urban transport is the product of Motor
Development International (MDI), a company registered in Luxembourg
whose tech-chic atelier lies in Carros, a palmy industrial suburb of
Nice, France. Guy and Cyril Nègre [above], the father-and-son team
behind MDI, predict their technology will find mass appeal in the
emerging city-car category, an automotive segment of small, efficient
cars well suited for crowded European and Asian cities and not meant
for long-haul trips.
Most carmakers think that battery power is the future for this
category, but the Nègres beg to differ. The AirPod, they promise, can
tank up in just 2 or 3 minutes using no more than 1.5 euros’ worth of
France’s nuclear-heavy, low-CO2 electricity to provide some 220 km
(137 miles) of city driving. It has no batteries to wear out and
replace—and so will cause no worries about its power source ever
erupting in flames. And the AirPod will cost a mere €6000, the Nègres
say (less than US $9000).
Storing energy in a long-lasting pressure tank made of carbon fiber
rather than in batteries, posit the Nègres, makes the AirPod cheaper,
more practical, and cleaner than a comparable electric vehicle (EV),
once you take manufacturing and disposal into account. It’s a bold
assertion, and one that remains to be proved, which won’t be possible
until these cute little cars actually hit the road. And when that will
happen is anyone’s guess.
Though the AirPod is supposed to go on sale in a couple of months, the
Nègres have been struggling to commercialize pneumatic vehicles for
more than a decade, incurring a reputation for unfulfilled promises.
No independent testing laboratory has assessed the AirPod’s
performance. And while deals over the past three years with India’s
Tata Motors and Paris-based Air France have bolstered MDI’s
credibility, it remains tough to find an automotive engineer who buys
into the company’s vision. The fundamental problem, they say, is the
laws of thermodynamics, which make compressed air an impractical power
source for vehicles. The AirPod’s 200-liter tank is roughly the size
of a common 55-gallon drum, but it carries the energy of little more
than a liter of gasoline. And its air-powered engine makes inefficient
use of it. MDI counters that the ultralight, low-speed AirPod needs
very little to get around. Yet skeptics abound.
“I don’t know how they can deliver what they claim,” says Denis
Clodic, a mechanical engineer and thermodynamics expert at France’s
prestigious École des Mines de Paris. “It’s not a solution for the
sort of vehicle we expect today,” says Pascal Higelin, professor and
director of the Mechanics and Energy Laboratory at the University of
Orléans, in France.
And yet Higelin and Clodic count themselves among the growing number
of propulsion authorities who say that vehicles combining compressed
air and fuel combustion could overcome the primary drawbacks of both,
providing an economical alternative to today’s gasoline-electric
hybrids. The greatest impediment to realizing such pneumatic hybrids,
according to these two experts, is that the failure of MDI’s air car
could cast doubt on the whole idea.
So if the AirPod does whoosh onto French streets within months as
promised, there will be quite a bit more riding on the quirky little
runabout than MDI’s fate. It could finally prove the viability of
compressed-air transport—or doom it for the foreseeable future.
Pod Squad: Workers at Motor Development International are busy
readying AirPod prototypes at the company’s fabrication facility near
Nice, France. Viewed from underneath its curvaceous shell [upper
left], the AirPod reveals an aluminum frame, which encloses a
composite tank holding air compressed to 350 bars [lower left]. A
steering wheel would be impractical, because the driver’s door is
located at the front of the vehicle. The solution is a joystick placed
next to the driver’s right hand [lower right].
Photos: Vincent Lignier
Pneumatic propulsion was high tech in the late 19th century, when
compressed-air engines and equipment became commonplace in Europe and
North America. Networks of compressed-air piping vied with then-
nascent electrical grids to power machine tools, railway hoists, and
switchyards, among other heavy gear. Meanwhile, the first jackhammers
were revolutionizing mining and tunnel construction. Propulsion uses
included pneumatic torpedoes, locomotives, and streetcars. Addison C.
Rand, founder of Rand Drill Co., lauded pneumatic streetcars in his
1894 guide The Uses of Compressed Air, noting that they had neither
the "distressing, jerky motion" of cable cars nor the capital costs of
electric railways.
Combustion-powered automobiles and buses ultimately prevailed, as we
all know. But a vestige of air propulsion survives in today’s Formula
1 racing pits, where blasts of air crank the big engines to life, and
it is from this world that Guy Nègre emerged. The self-taught mechanic
studied philosophy and worked in French carmaker Renault’s advertising
department in the 1960s before setting up his first engine-design
shop. There Nègre developed an unusual valveless engine for light
aircraft, a design that was never commercialized. Nègre’s second shop
extended the valveless concept to powerful Formula 1 race-car engines.
In 1990, a racing club installed Nègre’s engine for the storied Le
Mans 24-hour endurance race. But the engine refused to start, let
alone endure for 24 hours. This firm, like the one before it, slid
into obscurity.
In 1991, Nègre made the intellectual 360 that led to the AirPod.
Together with his son Cyril, then an engineer for Bugatti Automobiles,
Nègre formed MDI to develop low-emissions engines, and by 1996 they
had locked onto air propulsion. While both father and son’s names are
listed on the firm’s patent filings, Cyril is officially the R&D
director, and Guy is the president, responsible for selling their
vision.
The “thermo” of thermodynamics—the unstoppable flow of heat—makes
pneumatic propulsion a considerable engineering challenge. The
molecules of oxygen, nitrogen, and other gases in air give off heat
when compressed, representing a loss of energy up front. Do the
compression quickly, before the heat can dissipate into the
surroundings, and the losses rise further. And the trouble only mounts
when all this compressed gas is later released from the tank. The same
molecules cool when they expand, hence the chill on your hand when you
empty a spray can. Expand the gas slowly, and the pneumatic equipment
can stay warm by reabsorbing energy from the atmosphere. But power-
hungry vehicles must expand the gas quickly, so they are subject to
extreme cooling, which hampers the engine or, at worst, freezes its
air-feed lines.
By the late 1990s, MDI was talking up a first-generation engine it
claimed could handle these complications. Its design would expand air
in three stages, maximizing the opportunity to absorb heat, just as
efficient multistage gas compressors maximize heat dissipation. The
firm used this design to raise money, selling franchises for the local
production and sale of its vehicles and raising expectations. For
example, the sale of the first such franchise—rights to the Mexican
market—sparked press reports that smog-choked Mexico City would soon
mandate MDI’s “zero-pollution” technology for its 87 000-strong taxi
fleet.
Photos: Vincent Lignier
Tricycle Gear: Behind the driver are seats for two passengers [top
left]. Tanking up [top right] takes just a few minutes. Below, a test
car hits the streets.
By 2000, production was slated for 2002. In 2002, it was to begin in
2003. Indeed, commercialization was always just around the bend. But
the promised vehicles never arrived. Icing of moisture in the air-feed
lines, the pneumatic equivalent of plaque-choked blood vessels, sapped
efficiency and output. And the system was impractical to mass-produce.
“We could reach good efficiency with that [design]. We had ideas for
how to do it. But it was complex,” admits Guy.
From 2003 to 2007, MDI was dead in the water. Debts mounted while the
staff contracted, from a high of 50 employees down to 12. What saved
the firm was a simpler engine conceived in 2005 and now being readied
for the AirPod. In January 2007, Tata Motors purchased the Indian
rights to MDI’s technology for an undisclosed sum, widely reported as
$30 million, repairing both the firm’s finances and its tarnished
reputation. “It was clearly the patents, the designs for the new-
generation [motor] that convinced Tata to link up with us,” says Guy.
MDI’s second-generation design drops two of the three stages of
expansion and is thus simpler and more robust, the Nègres argue. The
key to efficiency, they say, is its pair of specialized,
interconnected cylinders [see diagram below]. Air released from the
tank is allowed to expand to 20 bars before being fed at constant
pressure to the first cylinder, which MDI calls the active chamber.
When the active chamber’s piston reaches full extension, a valve
attached to the air inlet closes. Only at this point is the air
allowed to expand, pushing its way into the second, larger cylinder.
Because the pressure in the active chamber is constant when the air
valve is open, the valve and air-feed lines don’t overchill. Only as
the larger cylinder’s piston moves does the air expand enough to
reduce the temperature past the freezing point—well past it: During
the exhaust stroke, the frigid air is expelled to the muffler at –40
to –70 C. “Once the valve is closed, you can cool [the air] a lot,
because if there is ice it will go to the exhaust,” says Cyril.
Illustration: Jason Lee
Double Duty: The AirPod’s engine uses two linked cylinders. Compressed
air flows into the smaller cylinder first at a constant pressure of 20
bars [1]. When the smaller piston bottoms out, the intake is closed,
and the air in the small cylinder expands, flowing into the larger
cylinder [2 and 3]. Both pistons then move to exhaust the expanded air
[4], and the cycle begins again. Click on image for a larger view.
See related video here.
By the end of 2007, Guy was once again promising imminent
commercialization, gearing up for production of a city-car sedan. But
MDI shifted course in January 2008, when the mayor of Paris announced
plans to station thousands of rent-by-the-hour city cars around town.
The competition to provide such ecofriendly personal transportation
would be fierce, but the rewards to the winner could be great. So Guy
dreamed up the AirPod as a pneumatic entry in that contest.
Anticipating a quick road-certification process, because this
featherweight minicar doesn’t exceed the 500-kg threshold for
requiring crash testing in the European Union, MDI decided to throw
its resources at the AirPod.
“That’s what MDI needs: to get a car on the market,” says Cyril.
The AirPod made quite a splash when it was unveiled in October 2008.
It was then that the mayor of Nice, who also leads the local regional
authorities (and, in a peculiarity of French democracy, serves in
President Nicolas Sarkozy’s government as well), committed the city
and region to testing compressed-air vehicles and, perhaps, to using
them in a Niçoise version of the Parisian car-rental scheme. A week
later, Air France and affiliate KLM signed up to test half a dozen
AirPods in their maintenance hangars.
Guy insists that within the first few months of 2010 MDI will have its
first assembly line at Carros churning out one AirPod per hour while
he and his son are coordinating the creation of three more assembly
plants set up by European licensees.
Could the AirPod be the vehicle that finally makes good on pneumatic
propulsion? Analysis of performance specs that MDI supplied to IEEE
Spectrum—among the first released by the firm—suggest that the
vehicle’s range may be less than a third of the 220 km (137 miles)
claimed. But with gasoline prices expected to rise along with global
temperatures, even that modest distance may be sufficient to interest
buyers.
According to MDI’s figures, the 80 kg of compressed air in the
AirPod’s tank has the potential to generate 11.2 kilowatt-hours of
mechanical energy when fully expanded at constant temperature—a truly
best-case scenario. The engine’s minimum operating pressure of 10 bars
will leave a few kilograms of air in the tank, trimming total usable
energy to 10.8 kWh. The process of expanding the air before it is sent
to the engine, however, gives this figure a lot more than a trim:
Dropping the pressure from 350 bars to 20 bars before the air can be
fed to the cylinders wastes nearly half the stored energy. So that
leaves just 5.6 kWh to spin the AirPod’s wheels. MDI vows that the
production version of its engine will somehow do better, providing 6.2
kWh of mechanical energy where the rubber meets the road. ”We know
what to do,” Guy says. But the firm’s best effort to date passed just
4.4 kWh to the wheels, he concedes. Because the AirPod requires 2.8
kWh to travel 100 km on a standard European urban driving cycle, the
numbers indicate that its range can be only about 160 km.
But even that figure sounds unrealistically high to outside experts.
Clodic of the École des Mines, for example, estimates that the
engine’s limited efficiency will provide only 1.9 kWh of usable
mechanical energy for a maximum range of 68 km (42 miles).
The efficiency stats look even worse when you include the energy cost
of filling the AirPod’s tank. MDI says its plant’s compressor is 58
percent efficient, near the top end for commercial units. Using MDI’s
numbers, this means that the AirPod’s plug-to-wheels efficiency is
currently just 23 percent. That makes an unflattering comparison with
the lithium-battery-powered EVs approaching the market, such as
Mitsubishi’s iMiEV subcompact car, which is expected to operate at
three times that efficiency.
The Nègres argue that although lithium-ion-powered EVs can beat the
AirPod’s efficiency by a large measure, they make for unrealistically
expensive cars. A lithium battery for the AirPod would cost almost as
much as MDI will be asking for the entire vehicle. Most city cars on
the market today use cheaper but heavier and less efficient lead-acid
batteries. As a result, estimates MDI, those EVs actually suck more
energy from the grid for each kilometer traveled than does the AirPod.
Doug Nelson, an expert in hybrid vehicles at Virginia Tech, in
Blacksburg, can’t confirm that assessment, but he agrees that
pneumatic vehicles could be a winner for the city-car segment if
lithium batteries remain too pricey.
The promise of a cheaper form of clean transport is indeed what
convinced Air France to consider AirPods, according to Jérôme
Bouteyre, the airline’s director of facilities management. EVs that
Air France has tested as runabouts for its maintenance crews cost
between 15 000 and 35 000—a steep jump up in price from vehicles of
similar size with internal combustion engines, which can be had for
less than 10 000. So the AirPod is economically competitive with
conventional vehicles of this sort, and critically, it meets Air
France’s modest needs—according to Bouteyre, a top speed of 30 to 40
km/h and a range of 10 to 20 km per day.
Motorists, however, have come to expect much more from their cars.
That’s why some of MDI’s critics think that automakers should be
focusing not on air-powered cars but on pneumatic-fuel hybrids. Unlike
cars running on compressed air alone, the greater power available from
pneumatic hybrids would suit full-function, highway-capable vehicles.
And compared with today’s hybrids, whose battery-equipped drivetrains
cost three times as much as an ordinary gasoline engine, pneumatic
hybrids could be priced for economy shoppers and for the developing
world. ”We have a system that provides 80 percent of the benefit and
costs maybe 20 percent extra,” says Lino Guzzella, a professor of
mechanical and process engineering at the Swiss Federal Institute of
Technology, in Zurich.
With support from German auto-components giant Robert Bosch, Guzzella
is testing small engines that use a 20- to 30-L compressed-air tank to
rival the performance of power plants twice their size. That tank is
filled with air pressurized to 20 bars using braking energy or spare
engine power. In this novel variation on conventional turbocharging,
that high-pressure air is then fed back into the engine along with
extra fuel to deliver precise bursts of power. ”We are able to burn
the fuel in a much more efficient way,” says Guzzella [see sidebar,
”Turbocharging the Turbocharger”].
MDI is working on an even simpler hybridization scheme, first
successfully employed in 1901 to extend the range of pneumatic
torpedoes. The idea is to add a small fuel burner upstream of the
engine to warm the air released from the tank, increasing the air’s
volume and thus reducing the amount required to charge the cylinders.
MDI claims this dual-mode system will triple the AirPod’s range, while
consuming just 0.56 L/100 km of gasoline (420 mpg). Clodic, however,
questions whether MDI possesses the discipline and resources to see
this hybrid system through.
MDI’s prospective industrial partners, Tata Motors and Air France,
seem to have a wait-and-see attitude. Air France, which originally
expected to begin testing AirPods in May and was still awaiting
delivery as this article went to press, isn’t worried, according to
Bouteyre: ”Either it’s built and corresponds to our requirements, or
it’s not and we won’t try it. We have nothing to lose.” The head of
corporate communications for Tata Motors, Debasis Ray, says his
company is licensed to use MDI’s technology in India, ”only as and
when it gets ready. We are not engaging beyond this at this point in
time.”
Guy’s response to the skeptics? He says that there is no such thing as
a truly independent expert for assessing novel vehicles: ”The only
evaluation possible is on the road.” True enough, but that’s only an
option if others can acquire examples of the finished product. And in
all the time that MDI has been working on vehicles, no product has
emerged. In the computer industry that’s known as vaporware, an
appellation that seems oddly appropriate for a car that runs on air.
This article originally appeared in print as "Driving On Air."
About the Author
Vincent Lignier photographed the green-car contender AirPod in Nice,
France, for "Driving on Air" [p. 30]. His biggest challenge in
capturing the futuristic pod was trying to even out the car's
reflection while shooting. "It's like an egg," he says. "If there's no
reflection in one part, it's reflecting somewhere else." Lignier's
work has been featured in such publications as Rolling Stone, Vibe,
Forbes, and France's Libération.
To Probe Further
To see an online slide show surveying other micro-size cars, go to http://spectrum.ieee.org/micro_cars
.
PAGE 12345 // VIEW ALL
TAGS: AIRPOD // MOTOR DEVELOPMENT INTERNATIONAL // AUTOMOTIVE //
COMPRESSED AIR ENGINE // PNEUMATIC PROPULSION // THERMODYNAMICS //
URBAN TRANSPORT
Name
Email
URL
Comment
1
Type the two words:
11
Comments will appear after moderation
BUDSNED 06.28.2010
I laugh every time I read blogs like this because they are filled with
people with very little or no technical or scientific knowledge
spouting off about what a wonderful invention has been developed. It
will save the world! Haha! I am a Mechanical Engineer with nearly 40
years experience in heavy industry and power. Air is an extremely poor
medium for storing and transmitting power. The losses in compressing
air to high pressure are huge. The work that can be done with 3
horsepower mechanically can require an air compressor ten times as
large - the rest of the power is wasted as heat. Even if power were
free and the heat did not contribute to heating the atmosphere and the
technological problems were surmounted, carrying that much high
pressure compressed air around would be exceedingly dangerous. In the
US, it requires a hazardous materials license and special precautions
to transport it. While there may be a wonderful technology found out
there someday that can effectively replace the internal combustion
engine, this isn't it. This is a scam just as running a car on water
where the only product in the exhaust is water. You can't get
something from nothing.
MARSUPY 06.06.2010
Hello! The article says : "No independent testing laboratory has
assessed the AirPod's performance" It's no more true ! At least, the
AirPod of MDI got European Community Whole Vehicle Type Approval !!!
YES !!! :o) See: http://www.mdi.lu/english/actualite.php To understand
the interest of storing energy in a compressed air tank rather than in
lithium battery, I give you again this link to an evenly updated
topic: http://air-car-concept.bb-fr.com/stockage-et-recharge-f9/comparatif-stockage-energie-air-comprime-vs-accus-t188.htm
Comments and addition are welcome for this compative little study.
Regards, Marsupy.
JOHN 06.05.2010
I do see a use for these cars. In congested cities in hot countries
they could be used as taxis, delivery or utility company vehicles.
They charge the tanks up at the taxi rank using an on-board electric
compressor, while waiting for a fare, with the exhaust used for the
internal a/c directly, or via a simple heat exchanger to warm it up
giving the correct temperature. No a/c refrigeration gases or anything
like that - just simple. Free simple cooling in the vehicle. . They
could be upsized to buses, and at each bus stop the bus hits an
overhead electric contact point which operates a charger to keep the
tank topped up. Again free simple a/c in the bus. .
JOHN 06.05.2010
Andrew said: "If the exhaust is really at -70C, it would be
interesting to see weather some electrical energy could be reclaimed
using a Stirling generator such as those manufactured by SunPower inc
in Athens Ohio, or MicroGen England. A beneficial side effect of
attaching such a generator would be that it would heat naturally the
exhaust as a side effect of producing electricity from the temperature
difference itself." . Why not by-pass the compressed air engine and
use the freezing compressed air directly out of the tank directly on
the Stirling engine?
JEPPS 03.29.2010
This car was supposed to be for sale every year since 1998. MDI sells
manufacturing licenses to investors and pre-orders but no car.
Performances and autonomy claimed by MDI surpass the laws of
thermodynamics. This is a scam.
JOHN 02.12.2010
MDI is a scam, this company sells only shares but no cars for 10 years.
FACT 12.22.2009
Yet another subject were the fact will soon be drowned by the scam
conspiracy theory AND the « oriented » corrupt scientist. Even if
compressors are used for a century to actually provide work (in the
physics sense) everywhere you will dare to look at, and even if the
physics involved are of third grade level. So even if compressed air
is a (very) weak density energy STORAGE, it is simple and efficient
and clean (no bad chemicals needed). Forget the compress loss, it is
heat and you will warm your home or your water with it. It can be both
produced locally (small scale) AND at bigger scale (instant filling
station) with child level technology (a bunch of LEGO will do). (BTW
Forget MDI engine, google Di-Pietro) All cars ARE electric since they
have a battery (around late sixties). Pull the first gear and you'll
be able to drive 1 miles if the wind blows right. Don't you understand
that electricity is not STORABLE ? The scam is to repeat the so called
break-trough is battery-life is going to happened in 10 years or so,
and hearing that repeated for 30 years. Buying a inefficient 300KG
battery à 10.000$ is a death sentence. All cars have (and will have)
electric ENGINE (air cars too), NO battery, and will connect to the
grid while travelling (a so called 'revolution' that train have
endured decades ago). So lests just pull the grid up the motorway. The
few miles from those lines to home, you will do on air/steam/bio-fuel
whatever/foot, that does not matters.
CHRIS KNIGHT 12.20.2009
Hi, I have been watching the development of the air engine for some
time now, since I first read about the MIDI from France, and knew the
resistance to get a more fuel efficient car onto the world market
would be fiercely opposed by the petrol and oil industry, and add
history will see you as having intrgrity and doing exactly what must
be done for the world as far a green house gas contribution is
concerned, if you require local Australian link maybe I can assist,
kkeep up the good work, regards chris Knight
ELI 12.19.2009
In an interview with Indian business newspaper DNA Money, the research
director of Tata Motors, S Ravishankar, said he encountered
difficulties with the technology. These problems include the limited
autonomy and the management of the air temperature.
MARSUPY 12.15.2009
@Charlie 11.05.2009 Yes, you're right but there are many many other
patents to read to discover the secret key! ;o) The magic phrase could
be "active chamber"...
MARSUPY 12.15.2009
Hello! See this mine of more than 15 videos in urban driving cycle ! - http://www.youtube.com/user/mdi06
- The MDI AirPod is at Copenhagen, by night ! :o) and has been
tested in many other towns ! = = = LOL! Warning !!! Franck & Thomas
works for batteries lobby ! You know, especially lithium batteries at
$1400/kWh. And you need a battery storing about 15kWh to get a range
of 100 miles... LOL ! do the math !
MICHEL 12.15.2009
MDI has made comments and answers to Berkeley report. http://www.mdi.lu/charge.php?nomfichier=Mistakes.pdf
Also available a complete comparative study (in french): http://www.mdi.lu/charge.php?nomfichier=Analyse-comparative---dossier---Annexes.pdf
Michel
SALMAN 12.11.2009
please can guy and cyril negre contact me on my
email:salmans at fsmail.net or my phone:07931346114 regards salman london
uk.
HELMUT HERTZOG 12.10.2009
Tanks can easily rupture at these pressures in accidents, very bad
news for nearby humans. Even Tanks wound with carbon fiber, very very
dangerious.
G.VIVEK 12.02.2009
I `m interested in developing air operated scooters for industrial (In
house use), can you help?
FRANCK 12.02.2009
Warning : MARSUPY and others pseudos work for MDI. MDI is a well-
organized scam.
THOMAS 12.02.2009
MDI is a scam, Guy Negre have sold many manufacturing licences to
naive investors since 2000, in Italy, Spain, France. These investors
have been unable to produce air cars because air cars haven't been
homologated by MDI' Spanish and Italian investors have took legal
action against MDI. Australian subsidiary IT MDI Technology also sells
licenses to manufature Guy Negre's air cars. http://www.itmdi-energy.com/
BASAV 11.27.2009
This is in news for more than few years now, this is really a very big
engineering challenge to convert compress air to mechanical energy on
continuous basis. How to accelerate? what happens when brakes are
applied? do you have option to change gears? All these would be
interested to know
SANTOSSH SHARMA 11.26.2009
will it be introduced in pakistan
K.PIPER 11.25.2009
smart
LI LIUSHENG 11.24.2009
How to buy a Airpod in China?
PAUL THEN 11.24.2009
Keep up the good work. It can only get better. PT
PETER FAIRLEY 11.24.2009
The New York Times hit MDI and air cars again just last week, with
Wheels columnist Jim Motavalli reporting on a UC Berkeley study poo-
pooing pneumatic cars "even under very optimistic assumptions about
performance." See http://wheels.blogs.nytimes.com/2009/11/20/study-says-air-cars-are-inefficient/
MD.SHAHID IQBAL 11.24.2009
i want to meet u.
CRUNCHER 11.22.2009
In my opinion, MDI and Negre are involved in an age old scam. Tata
paid $30m for the rights to manufacture a vehicle which doesn't exist!
Last year the NY Times published an article showing Negre inflated his
Formula One credentials, as noted here. http://wheels.blogs.nytimes.com/2008/02/27/an-air-powered-car-by-2009/
ALFRED RUFER 11.20.2009
On energy amount on board: A gasoline car with a 50 kg tank has 590
kWh energy on board (42.5 MJ/kg) An electric car with 200 kg of
batteries has only 20 kWh on board (100 Wh/kg) An electric car with
200 kg of batteries has only 6 kWh on board if the battery is on Lead-
acid base (30 Wh/kg) The air car with 200 liters reservoir at 300bar
has 10 kWh on board if we count with 50 kWh/cubic meter. The
technology is interresting, but shoud be compared with what is
comparable.
DAVE 11.19.2009
I came across this company years ago. I am very skeptical and would
like to see some independent test data. The available energy density
in compressed air is just so low by comparison to gasoline. Sure, this
thing could probably put put around a flat level lot for a while, but
I personally doubt this thing could ever make it up just one San
Francisco style hill with a passenger on board. I hope I'm wrong
because it would be ecologically great if that were the case, but 2+2
always = 4.
MICHAEL MATHER 11.16.2009
I think compressed air cars would be more efficient if the air tank
was insulated, so that the heat of compression is maintained. The loss
of that heat makes them inefficient. Also, after going through the
motor, the air would not be anywhere near so cold.
DONEE 11.13.2009
Loosing half the energy to an expansion pressure regulator is only
part of it. How do you get the air up to 350 bar in the first place?
Most compressors have these big fins on them to disipate heat, to
avoid overtemping the cylinders and rings. I would be supprised of the
typical air compressor capable of 350 bar was more than 50 percent
effecient. Put those two losses in line, and your down to 25 percent
before you even drive the motor.
OLDFOGY 11.13.2009
Cant help thinking this is not exactly new. Multi stage steam engines
for example have been arround for a long time.
OLDFOGY 11.13.2009
Like all the other "green" motive power alternatives. Where does the
energy come from that in this instance is used to compress the air in
the first place. How "green" is that process (the energy production) ?
MIKE 11.12.2009
In all the footage I've seen air cars are extremely noisy - and unless
compressed air is stockpiled they require four hours to recharge at an
electrical outlet, making the same amount of noise all the while. If a
city allows even a fraction of cars of this type, there will be no
moment of peace by day or night.
WILLIAM 11.11.2009
Wow, -90 degree exhaust air! Don't waste that! At the least, it could
run the air conditioning (direct? is that air clean?). And there's
obviously similar scope to extract some of that heat energy in the
compressive phase...
JIM BULLIS, MIASTRADA COMPANY 11.11.2009
Thanks for the insightful article. Also, thanks for the PV article of
last spring which you linked to
here
.---------------------------------------------------------------------------------------Now
how about getting an text editor that lets us write with paragraphs.
---------------------------------------------------------------------------It
is difficult saying serious things in a twitter like format.
BRUCE CARSTEN 11.11.2009
The "air car" sounds like a niche solution at best. Capital costs may
be low, but the very low efficiency of energy storage and recovery is
a show stopper for widespread application. Adiabatic compression and
expansion would theoretically be much better, but since it would be
hard to keep the compressed air from cooling off, it seems to me that
isothermal compression and expansion is the best practical, and by
dropping the pressure significantly before entering the motor the
situation is even worse. Taking the "low capital cost" model to a new
level, perhaps a wind-up,spring powered car should be considered.
ANDREW 11.09.2009
If the exhaust is really at -70C, it would be interesting to see
weather some electrical energy could be reclaimed using a Stirling
generator such as those manufactured by SunPower inc in Athens Ohio,
or MicroGen England. A beneficial side effect of attaching such a
generator would be that it would heat naturally the exhaust as a side
effect of producing electricity from the temperature difference
itself. I have personally worked with some of stirling electric
generators for military applications and from my experience is seems
possible to run a cylinder similar to ones they produce using the 90C
difference between the exhaust and the ambient air. Probably half of
the "Wasted" energy could be reclaimed as electrical energy, to make
an Air-Electric Hybrid and potentially extend the range, or at the
very least run all of the electronics in the vehicle. And as for
efficient "Green" compressors, the ones produced by Danfoss Turbocor
in Tallahassee Florida would be almost ideal for running an "Air Gas-
Station".
DAVID HAYNES 11.06.2009
Let's not write off compressed air energy storage as a means of
storing energy. There are a couple of facilities in the world that use
compressed air for utility-scale bulk-storage of electrical energy.
Their are other designs on the drawing board as well, and the
efficiencies appear to be as good as pumped hydro. While this is great
news to address the growing need for energy storage to stabilize the
grid, the challenge of using such a technology for transportation
purposes remains a considerable challenge. As Mr. Negre and the author
point out, battery powered vehicles tend to be costly. We also know
that today's fuel cell designs are costly. I would like to suggest
that ongoing research is needed into energy storage technologies. We
can't give up on batteries, hydrogen, fuel cells, or even air power in
our efforts to develop viable technologies that will sustain our way
of life into the future.
CHARLIE 11.05.2009
Marsupy, I have read and understand US Patent 7,296,405 by Cyril and
Guy Negre. It appears to be the US patent filing associated with the
link you provided. You should read it. While the patent is an
ingeneous and novel way of controlling the speed of an air engine,
there is indeed a 50% loss of energy in going from tank pressure (item
30) to the buffer tank (item 31 in the patent). Note that the air does
NOT do any mechanical work as the pressure is reduced at the input to
the buffer tank, and therefore that energy is lost.
MANFRED HOFFMANN 11.05.2009
How would this technology work for Golf Carts? There must be a multi-
million Golf Cart market around the world. It seems like the perfect
solution --- short distances to drive per day --- light weight (no
batteries to charge) etc. M.Hoffmann
MARSUPY 11.05.2009
Hello ! (3rd and last for today ;o) ) About range and Shiva's "20
miles" assertion... From: http://www.msnbc.msn.com/id/30930300/
"...Vencat expects it to go about 20 miles on compressed air alone..."
This actually means nothing ! What did exactly say Shiva ? What air
car model was he talking about (AIR-Pod, One, Mini, City) ? Each
vehicle has very different specifications (mass, front surface, drag
coef.) that do act on range ! Range of 20 miles at what constant speed
or in what driving cycle (city, highway, mixed...) ? Journalists
shouln't write papers about technology without minimum scientific
knowledges ! :o( So, Shiva said 20 miles (32km) of range ? Yes, it can
be true for the CityFlowAir model on highway, by example ! Ok guys !
Let's go "inside technology" & maths & physics ! :o) With these
parameters: Mass of vehicle 800kg+driver 70 kg+half empty tank 80kg :
950kg Tyres rolling resistance coef.:0.010 Front surface: 2.2m^2 Drag
coef.: 0.35 Constant speed : 130km/h (about 80mph) Tanks: 400
liters at 330bars(useful pressure) => 18.5kWh (max.theorical energy with
isothermal expansion using Van Der Waals model that is less
"optimistic" than real gas law calculation but more accurate with air
at 330 bars) Motor efficiency:35% (18% less than 43% claimed by MDI on
bench) Drive train efficiency: 95% using these well known formulas:
----------------------------------------------- * Power needed to
overcome rolling resistance *
----------------------------------------------- P roul. = f x g x m x
V with : ^x = to the power x f rolling resistance coef. = 0.010 for
asphalt (recent tyres) g acceleration due to gravity = 9,81 m/s^2 m
mass of the vehicle in kg V speed of the vehicle in m/s
------------------------------------------------------ * Power needed
to overcome air resistance if no wind *
------------------------------------------------------ P res.air = rho
x Cx x S x V^3 with : rho air density = 1.202 kg/m^3 Cx : Cd of the
vehicle S frontal area of the vehicle in m^2 V speed of the vehicle in
m/s ============================================ Total power needed to
run at V constant speed = P rol. + P air res.
============================================ ==> you get a maximum
range of 20 miles ! BUT, MDI's car are not intended to run on air on
highways but IN TOWN where it's more and more important to reduce the
pollution ! In urban cycle, the previous parameters give a range of
97km (60miles) that is rather good ! To leave cities, as say Shiva, an
external burner will be used to extend the range, with very low
pollution (full combustion, temperature<900°C). So, running on pure
compressed air in town will be soon an interesting part of the
solution to reduce local pollution and oil addiction by using
renewable energies to compress air. Just wait and see a few more
months, not years : AirPods are already running for tests in
streets ! Any comment or question ? Regards, Marsupy
MARSUPY 11.05.2009
Hello again ! "Dropping the pressure from 350 bars to 20 bars before
the air can be fed to the cylinders wastes nearly half the stored
energy" Do you actually think that Cyril and Guy NEGRE are so stupid
to lose 50% of the little stored energy ? Have a look at this
international patent and I think you may understand the weakness of
your assertion : http://v3.espacenet.com/publicationDetails/biblio?CC=PL&NR=373005A1&KC=A1&FT=D&date=20050808&DB=EPODOC&locale=fr_EP
I think it should be very interesting for Charlie ;o) Regards,
Marsupy.
MARSUPY 11.05.2009
2nd try... ============== Hello! This quite long paper needs yet more
information. To understand advantages and drawbacks of compressed air
tanks vs batteries, please see this bilingual post: h ttp://air-car-
concept.bb-fr.com/stockage-et-recharge-f9/comparatif-stockage-energie-
air-comprime-vs-accus-t188.htm#1427 ...and bring your questions and
comments ! (english spoken on this forum) Regards, Marsupy.
MARSUPY 11.05.2009
Hello! This quite long paper needs yet more information. To understand
advantages and drawbacks of compressed air tanks vs batteries, please
see this bilingual post: http://air-car-concept.bb-fr.com/stockage-et-recharge-f9/comparatif-stockage-energie-air-comprime-vs-accus-t188.htm#1427
...and bring your questions and comments ! (english spoken on this
forum) About efficiency of air compression process: Hey! Wake up
guys ! Reciprocating compressors are definitely old-fashioned ! ;o)
With new types of compressors, designed by engineers from the famous
"Ecole Polytechnique Fédérale de Lausanne"(EPFL, Switzerland), it's
absolutely possible to compress air with an excellent efficiency
(>78% !) thanks to liquid pistons or air-oil interfaces that allow an
almost isothermal process. Today, best reciprocating industrial
compressors have an efficiency of 50-55%. Sylvain LEMOFOUET, a young
engineer that made his thesis on the subject, has just created a
startup to bring this new invention to the market. See: http://www.bfe.admin.ch/php/modules/enet/streamfile.php?file=000000008102.pdf&name=240050.pdf
http://leiwww.epfl.ch/publications/lemofouet_rufer_epe_05.pdf http://www.swissnexboston.org/activities/activities/vl_0207_eid_lemofouetsylvain_enairys.pdf
or search his name on the web to see all his publications. That
offers a efficient way to store renewable but intermittent energy
(windmills, solar panels...). Moreover, this improve greatly the
global efficiency of the air car and brings it nearer electric cars.
Free bonus ! :o) Here is a very interesting report (.pdf in a .zip
file: 1.7MB) from International Energy Agency about evaluation of
different existing storage devices. http://mdi.cats.free.fr/Img/Evaluation_of_energy_storage_devices.zip
It shows that compressed air has its place ! :o) Regards, Marsupy.
RTATUM 11.05.2009
Ok, so it's not a perfect energy source for autos. However, in
combination with conventional gasoline or battery power, it could be
an alternate energy source for hybrids. There seem to be plenty of
other uses for such a system too, like powering a home emergency
generator or operating a lawn mower. The idea of not having to store a
can of gas in the garage is appealing.
PETER FAIRLEY 11.04.2009
CHARLIE mentions Shiva Vencat's 20 mile range comment in a May 2009
story by the Associated Press. Such statements to the press alarmed
MDI and in June the company asked Vencat (MDI's sole U.S. franchisee)
to cease acting as a spokesperson.
JFXY 11.03.2009
i would be cool if there were such cars in Belgium and if they work
CHARLIE 11.03.2009
The article says "Dropping the pressure from 350 bars to 20 bars
before the air can be fed to the cylinders wastes nearly half the
stored energy." ..................... but MDI says their efficiency is
43% now and will go to 60% later. How can the tank-to-wheels
efficiency be 60% if 1/2 the energy is lost in a tank-to-20 bar
regulator? ..............The 42 mile range estimated by Clodic of the
École des Mines is more in line with MDI's claimed 43% efficiency
being measured from the 20 bar pressure, not the
tank. ...................A director of MDI and CEO of the US
franchisee of MDI, Zero Pollution Motors, has said that the vehicle
intended for USA release has a range of about 20 miles on compressed
air. Google "Shiva Vencat 20 miles".
CHARLIE 11.03.2009
"So that leaves just 5.6 kWh to spin the AirPod's wheels. MDI vows
that the production version of its engine will somehow do better,
providing 6.2 kWh of mechanical energy where the rubber meets the
road." Either 1) your calculations are wrong, or 2) MDI's calculations
are wrong, or 3) MDI has invented the over-unity perpetual motion
machine. #2 is my bet.
DIDIER 11.03.2009
Well thank you for this very extensive, well made and very up-to-date
article. It is very instructive though less optimistic than I am. I
have been following the air cars closely for quite a time now, and
have made a website on them, called www.aircars.tk. So to anyone who
is interested and wants to see lots of information, pictures, videos,
links and the latest news, try it!
CHANDRASEKAR 11.02.2009
this article gave me a valuable information about air pod
IBM: A Practical Approach for Developing Multicore Systems
Mentor Graphics: Automated DRC Waiver Management
National Instruments: Developing Complex Control for Fuel-Cell-Powered
Industrial Vehicles
IBM: Strategic QA - Steps to Effective Software Quality Assurance
IBM: Practical approach for developing multi-core wireless systems
IBM: Modeling AUTOSAR systems with an UML/SysML profile
IBM: Improving traceability and auditability across the development
lifecycle
IBM: Driving business success with software reuse
IBM: Deliver robust products at reduced cost by linking model-driven
software testing to quality management
IBM: Achieving true collaboration in global development
IBM: Achieving Full Lifecycle Traceability from Requirements to Code
at Boston Scientfic
IBM: A new approach to verifying and validating medical device
development.
IBM: 10 Ways to Establish a Strategic Advantage in Managing Change
IBM: Turning Product Development into Competitive Advantage
IBM Smarter Products Webcast: The Payoff of Driving Requirements
Management Across Product Development
IBM: Driving product strategy from the top-down: How to align business
objectives with technical objectives
IBM: Smarter system development: a systems engineering trade study to
support green initiatives with model-driven development.
IBM: Enterprise Engineering at Boeing: Using Systems Engineering
principles to capture and manage business value
IBM: Leveraging the model-driven development and software product line
engineering synergy for success
IBM: Three keys to exceeding your customer's quality expectations
IBM: Developing Complex Control for Fuel-Cell-Powered Industrial
Vehicles
IBM: Five CIO challenges addressed by better change management
Mentor Graphics: An Innovative Method to Automate the Waiver of IP-
Level DRC Violations
National Instruments: Eight Rules for Prototyping
Keithley: Integrating Ultra-Fast Waveform Generation and Measurement
with Traditional DC I-V and C-V Measurements
APC: Allocating data center energy costs and carbon to IT users
Optimax: Asphere Metrology: Options for Measuring Aspheric Lenses
Mocana: Best Practices for Testing Secure Applications for Embedded
Devices
Mocana: Free Trial Software: NanoCrypto for Embedded Systems
Mentor Graphics: Developing a Complete Critical Feature Analysis
Solution - Part 1: What Is CFA and Why Do …
National Instruments: Build versus Buy - Understanding the Total Cost
of Embedded Design
Texas Instruments: Protecting RS-485 Interfaces Against Lethal
Electrical
COMSOL: Multiphysics Simulation Software
Dassault Systemes: Go Beyond Compliance for Profitability and
Environmental Sustainability
ADVERTISEMENT
ABOUT SPECTRUM CONTACT US PRIVACY POLICY TERMS OF USE
NONDISCRIMINATION POLICY ADVERTISING MEDIA CENTER IEEE JOB SITE RSS
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://gren.ca/pipermail/all_gren.ca/attachments/20100713/bdc33946/attachment.html>
More information about the All
mailing list