Do Electric City Cars Dream Of Compressed Air Sleep?

[Fat Albert]

Tata announce production of former Formula 1 engineer Guy Nègre's miniCat, a passenger vehicle powered by compressed air

Motor Development International have been developing compressed air powered vehicles for 20 years, they licensed the technology to Tata in 2009 who announced production last year and confirm deliveries to begin in 2012 in India.

The miniCat, a 3 seat vehicle has a maximum speed of 60mph (100kph) and a range of 180m (300km), about the same speed but with 6 times the range of hybrid vehicles running on pure electric power or 80% more range than the Nissan Leaf.



The car can be re-filled by compressors using similar technology as that for aqualungs and it takes less than 3 minutes for a 'full tank'

Far less polluting than battery powered vehicles the miniCat's production cost is less than the battery pack for a Leaf and it's running cost is predicted to be 1/10th of an equivalent sized battery/hybrid/internal combustion alternative.

Youtube Linky

[Redsfan]

Seems a great way to reduce our impact on the environment and help combat climate change.

[gibbothegreat]

Looks very interesting... what infrastructure is there for refilling on compressed air at present?

[_fb_]

I would think if you could pump up your tires, you should be able to refill your compressed air tank. So you'll need a shit load of quarters stateside

[gibbothegreat]

Slightly different pressures involved, would be amusing to see the meltdown of a standard garage compressor if asked to fill a tank to 4350psi...

On the subject of which, what happens to that in an accident? Imagine that would be potentially quite destructive, and difficult to protect without a disastrous weight penalty... just surmising here.

[colonel]

I would think if you could pump up your tires, you should be able to refill your compressed air tank. So you'll need a shit load of quarters stateside

f**king 50p over here

[Fat Albert]

Tata's proposal is that existing gas/diesel filling stations will fit new compressors to the forecourt, bear in mind that any forecourt which currently offers tyre inflation facilities already has a compressor. The vehicle has it's own compressor which can recharge the tank, admittedly taking several hours from a domestic supply.

The installation of suitably upgraded hardware would seem an order of magnitude less complicated and expensive that three phase, high current electrical systems (which would still require 10s of mins for a recharge) or battery swap infrastructure.

In any case, I simply make the point that the compressed air system offers similar performance with greater range and much lower energy/raw material/infrastructure costs than anything battery powered whether in production or conceived and does so at something like one fifth of the cost to the consumer.

If the Tata was volume manufactured it could sell in the States FOR LESS THAN THE BATTERY CAR SUBSIDY. Imagine your government giving you a car and change!

[Fat Albert]

On the subject of which, what happens to that in an accident? Imagine that would be potentially quite destructive, and difficult to protect without a disastrous weight penalty... just surmising here.

Are you suggesting that the explosive threat to passengers of an impact to a container designed to hold air at 400bar is greater than that of a fuel tank holding 45litres (10gals) of liquid fuel?

I know which I'd rather sit on

[_fb_]

blah blah blah...

If the Tata was volume manufactured it could sell in the States FOR LESS THAN THE BATTERY CAR SUBSIDY. Imagine your government giving you a car and change!

Dream on. Fiat are only just getting started now. And I'm sure Tata would find it nigh on impossible to meet US standards

[gibbothegreat]

The idea is appealing, but I still have some concerns: forget existing tyre inflators, you're talking a different order of compressor altogether to reach the pressures needed here (4350psi, according to one of FA's links). And the capacity to achieve that pressurization in 3 minutes would surely be extremely hazardous - can't think that any faciolity like that in industry wouldn't be ringed around with safeguards, requirements for protective clothing. FFS, people have been killed when inflating lorry tyres to (?)250psi.

And again, I do wonder what a tank even half full at 2,000psi would do in a serious crash. To make it strong enough to survive any serious impactwould surely carry a serious weight penalty... not dissing this for the sake of it, just reacting with gut enginnering instincts, would be very interested to know if these are reall issues, and if there are plans/existing ways of dealing with them if so.

[Fat Albert]

And I'm sure Tata would find it nigh on impossible to meet US standards

Er, Tata already sell in the States, you are aware that they own Jaguar & Land Rover?

Besides, the miniCAT was engineered in France to EU standards and you can buy a Smart across the pond these days.

Smart (as in IQ) Americans might consider buying one because they're so small, chances are that the typical redneck in his F150 would miss in a shunt simply because the recirculating ball steering and live axle suspension of a typical yank tank means you can't drive in a straight line

Gibbo

I repeat, the car was designed & engineered in France to EU standards

[gibbothegreat]

On the subject of which, what happens to that in an accident? Imagine that would be potentially quite destructive, and difficult to protect without a disastrous weight penalty... just surmising here.

Are you suggesting that the explosive threat to passengers of an impact to a container designed to hold air at 400bar is greater than that of a fuel tank holding 45litres (10gals) of liquid fuel?

I know which I'd rather sit on

Of course the fuel has hugely greater destructive potential, but that's irrelevant: it's become relatively easy to protect the liquid fuel, and the win win is that the way to do it is exactly not to make the tank stronger/thicker etc, but to surround it in a highly strong but flexible lining. The destructive energy of compressed air, whilst much less in theory, is infinitely harder to contain other than in structures which negate its very advantages - and would be potentially quite deadly enough irrespective of how it compares with petrol

[_fb_]

And I'm sure Tata would find it nigh on impossible to meet US standards

Er, Tata already sell in the States, you are aware that they own Jaguar & Land Rover?

...

But those are not Tata cars as such, so Tata itself would need to conform to US standards.

See: Australian sourced Pontiac GTO

[gibbothegreat]

I'm not having a go for the sake of it, genuinely interested in knowing if there are answers to these (surmised on my part) issues. Likewise, if anyone here has experience with working with high pressure air systems, how practical is it to repressurise to these levels in a matter of minutes in an unprotected environment?

[gibbothegreat]

Hmmm... from Wikipedia's entry on this:

The overall efficiency of a vehicle using compressed air energy storage, using the above refueling figures, is around 5-7%. For comparison, well to wheel efficiency of a conventional internal-combustion drivetrain is about 14%.

A 2005 study demonstrated that cars running on lithium-ion batteries out-perform both compressed air and fuel cell vehicles more than threefold at the same speeds. MDI claimed in 2007 that an air car will be able to travel 140 km in urban driving, and have a range of 80 km with a top speed of 110 km/h (68 mph) on highways, when operating on compressed air alone, but in as late as mid 2011, MDI has still not produced any proof to that effect.

A 2009 University of Berkeley Research Letter found that "Even under highly optimistic assumptions the compressed-air car is significantly less efficient than a battery electric vehicle and produces more greenhouse gas emissions than a conventional gas-powered car with a coal intensive power mix." However, they also suggested, "a pneumatic–combustion hybrid is technologically feasible, inexpensive and could eventually compete with hybrid electric vehicles."

Crash safety

Safety claims for light weight vehicle air tanks in severe collisions have not been verified. North American crash testing has not yet been conducted, and skeptics question the ability of an ultralight vehicle assembled with adhesives to produce acceptable crash safety results. Shiva Vencat, vice president of MDI and CEO of Zero Pollution Motors, claims the vehicle would pass crash testing and meet U.S. safety standards. He insists that the millions of dollars invested in the AirCar would not be in vain. To date, there has never been a lightweight, 100-plus mpg car which passed North American crash testing. Technological advances may soon make this possible, but the AirCar has yet to prove itself, and collision safety questions remain.

[gibbothegreat]

Hmmm... nothing immediately obvious on Tata's own website about this...

[gibbothegreat]

However, that Australian online mag FA quoted did lead to one interesting article around alternative vehicle technologies: http://www.caradvice.com.au/155195/lith ... s-by-2020/

US-based technology company IBM is developing a new type of battery that could give the next generation of electric cars a range of 800km.

The battery is based on lithium-air cell technology, which uses carbon electrodes rather than heavier metal ones in conventional batteries to react with oxygen and create electrical current.

The concept itself is not new, but IBM believes it has made a breakthrough that counters the biggest problem with lithium-air cells, which is their short lifespan.

California-based IBM physicist Winifried Wilcke told New Scientist magazine the key was developing an electrolyte that did not deplete when coming into contact with oxygen. He says the research team, which is supported by four US national labs and a number of commercial partners, has already created research prototypes of the battery and plans to have a full-size prototype ready for 2013.

Most of today’s electric vehicles use lithium-ion batteries, and the majority have a maximum range of 160km. With an estimated range five times greater than modern day EVs, vehicles powered by lithium-air batteries would be competitive with conventional petrol-powered vehicles. There is no word on how long a recharge would take.

IBM says the technology could be commercially available by 2020.

[slow wing]

Do Electric City Cars Dream Of Compressed Air Sleep?

Stop being a dick, FA.

[slow wing]

But seriously, I thought I killed this on the old bored. The energy efficiency is pants.


Why use electricity to compress air when you can feed it directly into the battery?


And what happens when you try to compress air? It heats up! So you also need a big refrigerator to counteract that. And lots of energy to run the refrigerator.


Better to feed a small fraction of that electricity directly into the battery and run the car from that...

[slow wing]

Ah, Gibbo, I see you have pre-empted my post with a quote from Wikipedia.

[Fat Albert]

Do Electric City Cars Dream Of Compressed Air Sleep?

Stop being a dick, FA.

It's hard not follow in the footsteps of someone so humble as you

Gutted that your risible predictions on electricity generation, fossil fuel economy and internal combustion engines have goooonnnnneeee

Having exposed your 1gw solar power station within 3 years garbage, I was looking forward to doing the same with your battery electric cars will out sell ICE within 10 years crap you made 5.5 years ago

There's just 4.5 years left Slowy and no one is buying a Leaf unless they ALSO HAVE an ICE vehicle as well, unit sales in the States fell to to 672 in November 2011, seems like all the eco-nuts that were going to, have bought one. For comparison Land Rover sold 4,743 4x4s in December 2011

Stop living in your dream world and face reality

[slow wing]

Do I have to capitalise "dick" for you, FA? Even then you probably wouldn't get it.

[Apposite]

But seriously, I thought I killed this on the old bored. The energy efficiency is pants.

Why use electricity to compress air when you can feed it directly into the battery?

And what happens when you try to compress air? It heats up! So you also need a big refrigerator to counteract that. And lots of energy to run the refrigerator.

Better to feed a small fraction of that electricity directly into the battery and run the car from that...

If battery tech improves and cost comes down it will be a clear winner over tech like compressed air but there is zero harm in looking at both, any alternatives to ICEs need to be explored.

The real issue of course is how we generate the energy to charge the battery or compress the air. If we can do that cheaply and sustainably (whether it be by wind, solar, nuclear fission/fusion, tide etc) then the choice of energy storage tech for the vehicles themselves is not that big a deal as long as it works.

[shaggy]

No different than LNG in terms of safety. Similar compressions and challenges.

[Odval]

But seriously, I thought I killed this on the old bored. The energy efficiency is pants.


Why use electricity to compress air when you can feed it directly into the battery?


And what happens when you try to compress air? It heats up! So you also need a big refrigerator to counteract that. And lots of energy to run the refrigerator.


Better to feed a small fraction of that electricity directly into the battery and run the car from that...

AFAIK, most aqualung compressors don't run on electricity. Aqualungs and compressors don't need any refrigerator. I might be wrong, but you could ask Pelo for what it's worth.

[6roucho]

Do I have to capitalise "dick" for you, FA? Even then you probably wouldn't get it.

I can just see Rutger Hauer in the role of Fat Albert.

[6roucho]

But seriously, I thought I killed this on the old bored. The energy efficiency is pants.


Why use electricity to compress air when you can feed it directly into the battery?


And what happens when you try to compress air? It heats up! So you also need a big refrigerator to counteract that. And lots of energy to run the refrigerator.


Better to feed a small fraction of that electricity directly into the battery and run the car from that...

AFAIK, most aqualung compressors don't run on electricity. Aqualungs and compressors don't need any refrigerator. I might be wrong, but you could ask Pelo for what it's worth.

Burning fuel to compress air seems even less efficient.

[deadduck]

On the subject of which, what happens to that in an accident? Imagine that would be potentially quite destructive, and difficult to protect without a disastrous weight penalty... just surmising here.

Are you suggesting that the explosive threat to passengers of an impact to a container designed to hold air at 400bar is greater than that of a fuel tank holding 45litres (10gals) of liquid fuel?

I know which I'd rather sit on

Of course the fuel has hugely greater destructive potential, but that's irrelevant: it's become relatively easy to protect the liquid fuel, and the win win is that the way to do it is exactly not to make the tank stronger/thicker etc, but to surround it in a highly strong but flexible lining. The destructive energy of compressed air, whilst much less in theory, is infinitely harder to contain other than in structures which negate its very advantages - and would be potentially quite deadly enough irrespective of how it compares with petrol

4350 psi or 30 MPa is a lot of gas but you can buy that commercially or industrially quite easily. The tanks can be any size required. Obviously for range you need more gas, and larger tanks would not scale well, being heavier than smaller tanks containing the same pressure, but you can easily rectify this by having multiple smaller tanks. These could weigh as little as 20kg each when full and still meet safety standards. That weight is not significantly more than a tank full of gas or a battery of cells for an electric vehicle.

The explosive danger could be reduced in risk with the correct alignment of the tanks in the vehicle. Of course all valves should be directed in such a manner that any breach would rocket the cylinder away from the vehicle in a direction to minimise threat to other vehicles. Otherwise they could be installed into the vehicle in such a manner to jet the gas in a safe direction whilst maintaining the cylinder inside the chassis.
The trouble and expense I foresee is the maintenance of the cylinders. Gas cylinders have a limited life span so the replacement and maintenance of these could become a serious expense for owners depending on the nature of the design, similar to the problems facing electric vehicles and battery life.

[easyray]

I would think if you could pump up your tires, you should be able to refill your compressed air tank. So you'll need a shit load of quarters stateside

f**king 50p over here

20p around our way

[Odval]

But seriously, I thought I killed this on the old bored. The energy efficiency is pants.


Why use electricity to compress air when you can feed it directly into the battery?


And what happens when you try to compress air? It heats up! So you also need a big refrigerator to counteract that. And lots of energy to run the refrigerator.


Better to feed a small fraction of that electricity directly into the battery and run the car from that...

AFAIK, most aqualung compressors don't run on electricity. Aqualungs and compressors don't need any refrigerator. I might be wrong, but you could ask Pelo for what it's worth.

Burning fuel to compress air seems even less efficient.

I was not having a go at anybody or technique here, merely trying and correct a point.
This said, you have a point and I gather all diving-related companies would love to have some efficient compressors running on something else than fuel.

[ovalball]

Do I have to capitalise "dick" for you, FA? Even then you probably wouldn't get it.

Classic Whoooosh moment.

[deadduck]

But seriously, I thought I killed this on the old bored. The energy efficiency is pants.


Why use electricity to compress air when you can feed it directly into the battery?


And what happens when you try to compress air? It heats up! So you also need a big refrigerator to counteract that. And lots of energy to run the refrigerator.


Better to feed a small fraction of that electricity directly into the battery and run the car from that...

With respect to the heating issue, refrigeration is not needed. Have you never heard of a heat exchanger or a cooling tower? The engineering challenges are all solveable it's just a matter of demand justifying the expense.

[Fat Albert]

Do I have to capitalise "dick" for you, FA? Even then you probably wouldn't get it.

Classic Whoooosh moment.

Honestly, the arrogance of yooof! FYI I read my first Phil K 20 years or more before you were born

Doesn't alter the fact that there's never going to be a compressed air version of Peak Lithium and that battery plug in vehicles remain wholly impractical for anything other than City/Second cars

Nobodys buying the Leaf Slowy despite it being streets ahead of any other pure electric, we'll see what the car buying public makes of the new generation of PEVs but you remain wildy, stupidly, laughably optimistic regarding PEV adoption, in fact you're in denial

[GigotHaricot]

Seems a great way to reduce our impact on the environment and help combat climate change.

How do you compress air ?

[slow wing]

Odval and Deadduck,

Fair point. Refrigeration is not needed. It just helps because it stores extra energy if you have it. Some divers refill their tanks in a water bath to keep it cool for the same reason - it gets more air in for a given pressure.

This technology does have an intrinsically low efficiency compared to electric cars though.

[deadduck]

Fair point. Refrigeration is not needed. It just helps because it stores extra energy if you have it. Some divers refill their tanks in a water bath to keep it cool for the same reason - it gets more air in for a given pressure.

Exactly. There are many ways of cooling without refrigeration. Cheap ways. Easy ways. It's not a valid argument.

This technology does have an intrinsically low efficiency compared to electric cars though.

Does it matter? It comes down to running cost.

[GigotHaricot]

Fair point. Refrigeration is not needed. It just helps because it stores extra energy if you have it. Some divers refill their tanks in a water bath to keep it cool for the same reason - it gets more air in for a given pressure.

Exactly. There are many ways of cooling without refrigeration. Cheap ways. Easy ways. It's not a valid argument.

This technology does have an intrinsically low efficiency compared to electric cars though.

Does it matter? It comes down to running cost.

Not just. Negative externalities and all that... The efficiency will eventually drive the running cost, if not now in a middle term.

Look at agro-carburant. They were the dogs bollocks on a small scale until they drove the colza prices off their tits.

[iul]

The problem with air compressed cars is their low efficiency. The problem with battery powered cars is their high cost / limited life for the battery / potential environmental hazards if the batteries aren't discarded properly.
The real solution is this:

Have them run in cities like trams/ trolleys do: Build an overhead electrically charged mesh the cars are connected to by a high rod.
It would only work for cities, but it would probably be cheap to build and run.

[Odval]

The problem with air compressed cars is their low efficiency. The problem with battery powered cars is their high cost / limited life for the battery / potential environmental hazards if the batteries aren't discarded properly.
The real solution is this:

Have them run in cities like trams/ trolleys do: Build an overhead electrically charged mesh the cars are connected to by a high rod.
It would only work for cities, but it would probably be cheap to build and run.

On second thoughts, yet, it would be great to see all the urban types stuck in the cities while we could roam and drive everywhere.

[gibbothegreat]

Exactly. There are many ways of cooling without refrigeration. Cheap ways. Easy ways. It's not a valid argument.

And yet it seems this is one area that has defeated Tata - without this it's nigh on impossible to achieve the requisite energy density, and no-one has really figured out how to make it work cost-effectively.

One other question to which I haven't seen any reference: how do these vehicles produce power for lights, steering, braking, defrosters, heaters, etc...?