2015 Geneva Auto Show



March 6, 2009

MDI's compressed air powered AIRpod

MDI's compressed air powered AIRpod

Image Gallery (12 images)


Now that petrol has come down to a more affordable price around the world, there seems to be less urgency surrounding alternative fuel vehicles. But the money that went into fossil fuel alternatives in the last several years is bearing fruit on a number of fronts, with battery-electric vehicles appearing the most likely alternative to make the jump into the mainstream. Car companies are still pushing Hydrogen as a solution, but we'd tend to view that as a red herring - a solution far more amenable to petrol distribution companies than to customers or the energy economy at large.

Compressed air has been developing much more quietly - we haven't seen anything from the major auto companies, unlike hybrids, hydrogen and battery cars which dominate the concept car stands at most auto shows now. But air cars certainly have their practicalities as a petrol alternative, and there are several in development.

While electric car makers are battling for glamorous power figures and shooting for the top end of the market, compressed air car companies like ex-Formula One engine designer Guy Negre's MDI are aiming to prove themselves as contenders in economy and utility. Requiring no exotic battery materials, and using primarily aluminum construction (even in the engine block) keeps air cars light and cheap - to the point where Indian manufacturer Tata, in partnership with MDI, believes it will be able to offer air cars at a price competitive enough to make them a realistic option for the average Indian worker.

But while the company works towards a forecast 2010 launch for its sub-$20,000 American air car product, it's also looking at how the compressed air engine might be able to offer completely new transport options.

One of the more interesting ideas - and the one that MDI claims will launch first of all - is the AIRPod. A three-wheeled minicar, the AIRPod allegedly seats 3 adults and a child - although it looks much more comfortable as a 2-person vehicle, with back-seat passengers facing the rear to conserve space.

The large glass door opens from the front of the pod - the driver controls the vehicle using a joystick instead of a full steering column, so vision ahead is pretty much unhindered. Despite the pod's fairly large interior volume, the chassis is all made from sandwiched fiberglass and polyurethane, so it's super light. Weight is kept down to a miniscule 220kg, which helps squeeze performance and range from the tiny 180cc aluminum compressed air engine.

The compressed air tanks on board can store a maximum of 175 liters of air at a pressure of 350bar - or around 5080 psi. That's about 180 times as much pressure as you'd put in your car tyres, so you'd be right to be worried about a hell of a pop if they get punctured. While it might be a scary experience, though, it's unlikely to be dangerous, as the carbon-fiber/thermoplastic tanks are designed to split and release the air instead of shattering and exploding like a metal cylinder might. Still, there's not much safety and crash test data floating about just yet.

The tiny motor can make about 5 1/2 horsepower, which, combined with the low weight and aerodynamic shape of the AIRPod, allow it a top speed around 70kmh. Range under ideal circumstances would be around 220km - although in the stop-start city traffic and to-and-fro baggage carrying environment the pod is designed for, you'd expect that range to drop significantly.

Refilling the air tanks can allegedly be achieved in 1.5 minutes for a cost of EU1.10 - but filling up this fast might have some heat consequences and we'd expect a production version to take a reasonable amount longer.

The front wheel is actually a two-wheel dolly not unlike that at the front of a jumbo jet, and the AIRPod's steering is controlled by driving the rear wheels at different speeds.

It's an interesting idea - but we've got to admit the main reason we'd like to see the AIRPod come to market soon is that we want to see how compressed air will stack up against battery-electric vehicles in the longer run. Since electric vehicles are well proven through decades of use in things like golf and baggage carts, perhaps a mini-pod like this one is a good way to evaluate compressed air's potential in the market.

Loz Blain

About the Author

70kph. 220km. =3,14h? 5,5hp= 4kW? =12,56kWh?

12,56kWh for 1,1 Euro makes a very good compressor and air engine?

3-4 tanks and you do not need a battery EV?

Always doubt until it is proven?

diesel ola
7th March, 2009 @ 10:39 pm PST

I'm just curious, it will be considered "Hybrid" if AIRPod will come equiped with a battery powered air compressor? With a small battery, to remove it when at home, and charge it at the wall socket. It will increase the range big time. And you will never have to stop at the gas station!

9th March, 2009 @ 10:18 am PDT

Excuse me for double posting, but speaking about safety and tests, how many quads, mopeds, scooters and motorbikes have to pass these tests? What about golf carts, segways and all other vehicles allowed on the public roads.

9th March, 2009 @ 10:23 am PDT

I have been watching this idea develop for a long time, and really think you should acknowledge the originators over at www.mdi.lu

The Frenchmen who have been working on this engine for nearly 10 years have developed a very complex piston action to extract maximum energy, visible in the engine graphic.

My one reservation with the design is that I can see these engines being awfully clattery when they age.

Otherwise - how good is the idea for the average commute? Very.

9th March, 2009 @ 06:49 pm PDT

Gruitamarius: The trick for the US roads is to build a trike, something to do with the vehicle only having three wheels keeps it from having to abide by automotive rules. If I'm not mistaken its thereby classified as a motorcycle. Otherwise, it falls under the jurisdiction of intense scrutiny through carefully crafted foreign-competition-unfriendly safety standards. (Tangent: Does the US really need to have rules which are so different from EU that we simply can't drive the same car?...reciprocity would be nice especially for the ranger 2.5TD)

diesel ola: I'm sure that the max. speed and max. range do not occur at the same time. I'm guessing the range would be about an hour at that speed if that considering the unwieldy shapes I've seen so far.

I truly love the approach to the problem as its a mechanical engineers dream, a solution based in the fundamentals of a typical undergraduate education. I believe it could work, and would be a tremendous benefit to urban traffic at least. 2010 is coming up... I want to see this work.

9th March, 2009 @ 07:54 pm PDT

The Airpod certainly looks interesting. My weekly journeys are (1) Main shopping 8 Km away, (2) Local shops 1 Km, (3) Church 10 Km, so the Airpod should be ideal.

With the Ford Falcon I currently drive, going up the car park ramp is a matter of estimation where the ramp sides are - No bother with the Airpod. Parking - No bother with the Airpod. Space for the shopping - No bother with the Airpod.

Where to get the compressed air - would be difficult at present unless one had a special 'Home Compressor'.

Look forward to hearing more about it.

William Jackson

Sunshine Coast, Queensland, Australia

9th March, 2009 @ 10:52 pm PDT

There is not an independent engineer or a journo anywhere in the world who has tested these vehicles for range.

Compressed air - or hot air - or vapourwair?

10th March, 2009 @ 06:39 pm PDT

FYI, an old episode of "Modern Marvels" called "Enivironmental Tech II" aired twice this week already which features MDI's engine, there's even a short clip of the van version driving around.

11th March, 2009 @ 03:24 pm PDT

You're right of course Stuart21 and diesel ola - test systems have all been very short range affairs to date and we haven't seen anywhere near the claimed potential mileage demostrated as yet.

I'd also very much like to see how compressed air stacks up as a "battery" - can it stack up to lithium-ion batterines in terms of grid-to-wheels energy efficiency? I very much doubt it.

Still, batteries do take a long time to charge, and they're expensive - which are two of the key barriers that will prevent one-car families from going electric for some time, even if the majority of their driving is done around town. Compressed air cars can be filled up fairly snappily at a properly-equipped service station, and the equipment itself is nothing particularly special. The cars should also be loads cheaper than electrics.

So if the range issue gets sorted out, air cars do look like a wonderfully practical petrol alternative.

11th March, 2009 @ 09:04 pm PDT

Thanks tgmeob - yes, I've seen the video but didn't post it as it was relating to a previous MDI model that we've already covered, and not the AIRPod. For those who haven't seen it -

11th March, 2009 @ 09:06 pm PDT

Somewhere I saw exact calculations why aircars are impossible from the compressed air energy storage point of view. You simply cannot ever store enough energy under reasonable pressure to drive the car far enough. You go for 5 minutes not 5 hours. It is a hoax. Their results support this sceptic position. One more neverland cash cow. It is such a pity. I also would love to have one cheap reliable pod for my modest needs. This wil never happen.

11th July, 2009 @ 03:20 am PDT

There is not a chance in hell this car will ever be produced. It has no range. I'd be surprised tp see it get 3 miles at 40 mph. It's basic physics 101.

23rd July, 2009 @ 02:04 am PDT

Loz. You mentioned a possible heating problem when re-filling with air. This is only a consideration when re-filling at home. If you re-fill at a filling station , the air is already at high pressure, and you are just transfering the air into your tank. At home, the air heats up as you compress it, and the heat would need to be dissipated. You could have a spare compressed air tank for an immediate re-fill. This tank could charge while you were out, and cool off by itself. By the way, the heat could be piped into the house, so as to be energy efficient. I understand some models of the air car will have a small motor on board, to run a compressor, and also to provide some heating in cold climates. One question puzzles me. Why are hybrid cars more efficient than regular cars?

23rd July, 2009 @ 08:51 am PDT

Compressed air cars,EVs,Pedal operated hybrid bikes ... gives hope in the forecast of dismal future of dwindling oil resources.

Dr.A.Jagadeesh Nellore(AP),India

29th April, 2010 @ 07:31 am PDT

Given that MOST cars sit there unused most of the time, a 2 x 1 meter solar panel of 120 - 160W, and a small high pressure compressor, might be able to keep this running indefinitely with little or no recharges from the mains - more so in some areas, and less so in others.

Mr Stiffy
5th October, 2011 @ 09:42 am PDT
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