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How Chrysler's Battery-Less Hybrid Minivan Works

Soulskill posted more than 3 years ago | from the batteries-are-so-2010 dept.

Transportation 347

thecarchik writes "Chrysler announced Wednesday that it would partner with the US Environmental Protection Agency to build and test prototypes of a different kind of hybrid vehicle, one that accumulates energy not in a battery pack but by compressing a gas hydraulically. The system in question, originally developed at the EPA labs, uses engine overrun torque to capture otherwise wasted energy, as do conventional hybrid-electric vehicles. The engine is Chrysler's standard 2.4-liter four-cylinder, the base engine in its minivan line. But rather than turning a generator, that torque powers a pump that uses hydraulic fluid to increase the pressure inside a 14.4-gallon tank of nitrogen gas, known as a high-pressure accumulator."

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I'll tell you how (-1)

Anonymous Coward | more than 3 years ago | (#34989222)

It does it by adding CO2 to the atmosphere, and stealing the world from your children.

how second post works (-1)

Anonymous Coward | more than 3 years ago | (#34989232)

i stick my dick in your pooper.

That is cheating (-1, Troll)

Suki I (1546431) | more than 3 years ago | (#34989234)

Fart propulsion will give those sports fan boys the ecological advantage. Who wants that?

Re:That is cheating (0)

Anonymous Coward | more than 3 years ago | (#34989300)

Boom.

Re:That is cheating (0)

Suki I (1546431) | more than 3 years ago | (#34989390)

Boom.

Exactly!

Sounds inefficent (0)

Anonymous Coward | more than 3 years ago | (#34989272)

Generators cause drag so you loose some energy but this type of system would add friction into the mix which would waste more energy. Seems more like an energy shell game with looses from friction along the way.

It's worse then that. (1)

HornWumpus (783565) | more than 3 years ago | (#34989314)

There is a theoretical limit to how efficient a compression/expansion 'battery' can be.

I don't recall the formula, I'm sure some /.er with more recent thermo then I will come up with it.

I do recall that to get decent efficiency the high pressure side needs to be very high pressure.

Re:It's worse then that. (1)

hawguy (1600213) | more than 3 years ago | (#34989506)

There is a theoretical limit to how efficient a compression/expansion 'battery' can be.

Ideally speaking, if you prevent heat loss, PV=nRT says that it can be 100% efficient.

I do recall that to get decent efficiency the high pressure side needs to be very high pressure.

Like 5000psi?

Re:It's worse then that. (4, Informative)

florescent_beige (608235) | more than 3 years ago | (#34989712)

The problem can be with the T. The hot compressed gas cools to ambient over time, dissipating energy (seen as a loss of pressure). I suppose, though, the energy is used before much heat has a chance to leak away. Barring that the limit on efficiency is the mechanical losses in the motor you drive with the gas.

You don't need particularly high pressures to make it theoretically efficient. You may be thinking of heat engines based on Otto (piston) or Brayton (turbine) cycles where efficiency is related to the pressure and temperatures at combustion, the higher the better.

Re:Sounds inefficent (2)

hawguy (1600213) | more than 3 years ago | (#34989426)

Generators cause drag so you loose some energy but this type of system would add friction into the mix which would waste more energy. Seems more like an energy shell game with looses from friction along the way.

Why is it that this system would necessarily waste more energy than a electrical system? You say that this system would add friction, which is just another word for the "drag" that the generator adds in an electrical system. Why is this more of an energy shell game than an electric hybrid? It's just replacing the generator/battery combo with a compressor/accumulator combo.

Assuming that it's mostly a short-term compress/decompress cycles, as long as the accumulator is well insulated to prevent heat loss, it should be fairly efficient. Perhaps more efficient than a battery.

This article suggests that a hydraulic/compressed gas system can have 75% energy recovery for start/stop conditions as compared with 15 - 20% for a gasoline-electric hybrid:

http://www.scientificamerican.com/article.cfm?id=hydraulic-hybrid-vehicle [scientificamerican.com]

Re:Sounds inefficent (0)

Anonymous Coward | more than 3 years ago | (#34989680)

One thing to remember is that "conditioned" electricity is expensive electricity -- if you want it with certain wave forms or regulated then it gets expensive fast.

Re:Sounds inefficent (4, Informative)

tibit (1762298) | more than 3 years ago | (#34989732)

What people sometimes forget about is that such a cycle can be theoretically 100% efficient: it's called the reversible adiabatic process -- completely reversible! As long as your gas storage system is well insulated and has low thermal masses, that is. You simply compress and heat up the gas and store it. Later on, you decompress and cool down.

Think of a gas sealed in a well-insulated, low thermal mass cylinder. You do some work to move the piston in, the gas heats up and compresses. You release the piston, the gas does the same work going out as it expands and cools down. If the system is perfectly isolated and there is no friction, you get exactly the work you put in.

This has the theoretical potential of being a rather nifty thing, but I don't know how the practical (engineering) side of things works out. It may be impractical, or may be not. Time will tell.

Re:Sounds inefficent (3, Interesting)

DCFusor (1763438) | more than 3 years ago | (#34989952)

Well, perfect *anything* isn't reality. A perfect battery would also be 100% efficient, you know. In reality, you lose so much thermal energy that this doesn't work all that well -- and the piston and cylinder remain the main things hot after you let the gas out -- lost energy at some point when that leaks back into the environment. In any small system they have much more thermal mass than the gas does.

As a scientist who lives off the grid on solar PV (for decades now), I've pretty much investigated every way there is to store energy, and it's not so simple a problem. Vanadium redox batteries (utterly impractical for autos and that membrane ain't cheap) look about the best so far in terms of simple and good while being efficient. Most things that do heat storage are only efficient if huge enough that the surface area to volume ratio can be really small.

The above approach might work out fine for small amounts of energy and for short times, however, and having some is better than nothing -- it probably is pretty reliable unlike most batteries which tend to have much shorter cycle life than is claimed. I think we're going to see a big backlash against battery cars at some point because of that one.

Yep (1)

Anonymous Coward | more than 3 years ago | (#34989538)

As far as I have seen there is no future in compressed air vehicles*. Possible efficiency improvements are predictable, and nowhere near the point where anyone should be developing prototypes.

It comes down to this being a morally corrupt waste of money.

*Fixed site to site vehicles (trains and similar) can feasibly use compressed air, however the fuel options for these systems is quite large and can reach much higher efficiency.

Re:Sounds inefficent (2)

Waffle Iron (339739) | more than 3 years ago | (#34989626)

Generators cause drag so you loose some energy but this type of system would add friction into the mix which would waste more energy

A bigger engine with 2 extra cylinders (to match the performance of this 4-cylinder hybrid) also adds friction, and it does so all the time the engine is running.

I would assume that this gas compressor can be disengaged with a clutch when not needed, so the friction losses could actually be less overall for the same max power output.

14.4-gallon tank of nitrogen gas? (-1)

Anonymous Coward | more than 3 years ago | (#34989274)

not anymore

Boom! (1, Insightful)

Sponge Bath (413667) | more than 3 years ago | (#34989280)

This sounds like an excellent alternative to explore, but I do wonder how that 5000 PSI reacts when crushed in an accident. CNN describes the tank as a "bladder".

Re:Boom! (3, Funny)

Brett Buck (811747) | more than 3 years ago | (#34989336)

If it's holding 5000 PSI it will be pretty difficult to crush.

Re:Boom! (3, Funny)

Anonymous Coward | more than 3 years ago | (#34989552)

A two-ton SUV moving at 80 miles an hour agrees with you, but doesn't give a fuck

Re:Boom! (0)

c0lo (1497653) | more than 3 years ago | (#34989574)

If it's holding 5000 PSI it will be pretty difficult to crush.

Puncture, then? Or maybe just a tiny crack will do?

Re:Boom! (3, Insightful)

noidentity (188756) | more than 3 years ago | (#34989582)

If it's holding 5000 PSI it will be pretty difficult to crush.

Now there's an idea! If crushed in a wreck, it would be holding more energy. Storing the energy of wrecks could become the new eco-friendly feature in cars.

Re:Boom! (0)

Anonymous Coward | more than 3 years ago | (#34989462)

Ever watch Mythbusters. I would guess pretty much the same as a Scuba tank, but instead it is connected to the frame. The psi are pretty close. If the car was dangerous we would probably hear incidents with scuba tanks in cars. I am pretty sure that the safety has been rigorously tested and then some. The car industry has tonnes of experience with poor designs and how they damage images.

Re:Boom! (2)

adolf (21054) | more than 3 years ago | (#34989562)

SCBA tanks are required to be tested every 5 years at 5/3 of their rated pressure. I wonder if the Chrysler tanks will be due similar scrutiny...

In terms of "bladder," it's probably not a misnomer: Similar to an expansion tank [wikipedia.org] on a hot water system, or a pressure tank on a well system, the factory-installed nitrogen will be separated inside the tank from the newly-introduced compressed gas by rubber.

FWIW.

Re:Boom! (4, Insightful)

Anonymous Coward | more than 3 years ago | (#34989482)

If you have ABS, you already have something like this in your car. It's a little (1qt) metal sphere with a rubber diaphragm in it. It holds about 3,000PSI of Nitrogen in order to cycle the ABS when it activates.

As for the safety...well... how safe is it to carry around 20 gallons of highly flammable gasoline?

Re:Boom! (-1)

cynyr (703126) | more than 3 years ago | (#34989638)

i only carry around 12, and thats only right after a fill up you insensitive clod!

Re:Boom! (1)

adolf (21054) | more than 3 years ago | (#34989642)

If you have ABS, you already have something like this in your car. It's a little (1qt) metal sphere with a rubber diaphragm in it. It holds about 3,000PSI of Nitrogen in order to cycle the ABS when it activates.

Really? Where do I find this on my car? I don't see it anywhere [realoem.com] .

Nor have I seen it on any of the other ABS-equipped vehicles that I've owned.

Can I have some of what you're smoking, though?

Re:Boom! (0)

Anonymous Coward | more than 3 years ago | (#34989698)

About 10 seconds on Google will show you that they are in BMWs

Re:Boom! (0)

Anonymous Coward | more than 3 years ago | (#34989838)

OK, so on the diagram you reference [realoem.com] it's actually a cylinder instead of a sphere (hint: "hydro unit.") Still, nice use of a flimsy excuse to be nit-picky and abusive.

Re:Boom! (1)

Pentium100 (1240090) | more than 3 years ago | (#34989852)

Gasoline is just a liquid until it is ignited (Mythbusters found out that a dropped cigarette is not enough to ignite gasoline), so in a crash you need a source of a lot of heat for the gasoline to ignite. OTOH, Li-Ion batteries ignite if they are punctured. A high pressure tank can explode if punctured. Again, no need for a flame (though if you heat the high pressure tank it explodes more violently, since the internal pressure depends on the temperature).

Re:Boom! (1)

c0lo (1497653) | more than 3 years ago | (#34989892)

(though if you heat the high pressure tank it explodes more violently, since the internal pressure depends on the temperature)

Use a sacrificial valve (introduce a "defect" on purpose to control in which point in which the tank will blow. No explosion when over-pressurized/heated).

Re:Boom! (4, Interesting)

Sarten-X (1102295) | more than 3 years ago | (#34989548)

In an accident, it will remain intact. If not, then the car won't pass standard safety tests, and the manufacturer knows it won't sell. In the event that some freak crushing blow strikes the tank (like, for example, getting caught between a freight train and a reinforced bunker, or perhaps dropped from an airplane) It'll most likely burst open at the one spot that the engineers intentionally design to be slightly weaker than the rest of the case, which conveniently releases the contained gas in a harmless direction.

5000 PSI is like having an average American car, including all passengers, with all its weight sitting on a single square inch. That's the maximum operating pressure, implying that the tank itself will actually hold significantly more pressure before having any problems. I feel pretty confident that the engineers involved know what they're doing, and can prevent catastrophic failure during a collision.

Re:Boom! (1)

Surt (22457) | more than 3 years ago | (#34989580)

Since they aren't holding much more energy than a gas tank or battery, can the risks due to catastrophic failure really be significantly greater?

Re:Boom! (4, Funny)

PPH (736903) | more than 3 years ago | (#34989794)

CNN describes the tank as a "bladder".

Damn! Now that's two bladders I'll be emptying when an accident occurs.

Re:Boom! (1)

whiteboy86 (1930018) | more than 3 years ago | (#34989884)

The tank is kevlar reinforced composite, so when the damage occurs (in an accident) it just fizzes off and doesn't explode.

Which is a more dangerous battery? (2, Interesting)

rsborg (111459) | more than 3 years ago | (#34989292)

FTFA:

That compressed gas, stored at pressure as high as 5,000 pounds per square inch, represents energy waiting to be released.

Not sure I'd want to be an a 1.0 version consumer vehicle with that much pressure without some serious discussion about the safety precautions to prevent or mitigate "unexpected pressure drops".

Can someone who's got more experience with the fluid mechanics add to this?

Re:Which is a more dangerous battery? (2)

M. Baranczak (726671) | more than 3 years ago | (#34989416)

More dangerous than riding around with a tank of explosive liquid?

Re:Which is a more dangerous battery? (0)

Anonymous Coward | more than 3 years ago | (#34989446)

More dangerous than riding around with a tank of explosive liquid?

Despite what television may have told you, flammable explosive.

Re:Which is a more dangerous battery? (0)

Anonymous Coward | more than 3 years ago | (#34989618)

Sorry, that was meant to be "flammable <> explosive".

Re:Which is a more dangerous battery? (1)

EvanED (569694) | more than 3 years ago | (#34989630)

Read "with a tank of explosive vapors" if you prefer.

Re:Which is a more dangerous battery? (2)

noidentity (188756) | more than 3 years ago | (#34989492)

Correct me if I'm wrong, but this would be in addition to a tank of explosive liquid.

Re:Which is a more dangerous battery? (1)

AvitarX (172628) | more than 3 years ago | (#34989646)

Good thing my tank of flammable liquid isn't 1.0 (of course, the Pinto shows that revision 1.0 of any model can be dangerous).

Re:Which is a more dangerous battery? (0)

Anonymous Coward | more than 3 years ago | (#34989966)

Yes in fact. The entire reason why gasoline and diesel are such ideal fuels besides their incredible energy density is that they a very stable for their energy level, diesel in particular.

SCUBA tanks aren't supposed to be left unsupervised standing vertically for fear that they might fall over. In the event that a regulator should fail, a high pressure tank can easily punch a hole in a concrete wall. They're essentially a rocket made from 40 pounds of aluminum/steel in geometry suited for penetrating barriers.

That said, every day SCUBA guides and instructors put dozens of these tanks in the back of Vans and Pickup trucks without incident. Every day commercial welders and industrial gas suppliers drive down the highway with oxygen and acetylene tanks.

Should Suzie soccer mom be allowed to drive one? I guess Chrysler's lawyers decided the risk isn't significant enough to say "no".

Scuba tank's burst disc ... (4, Insightful)

perpenso (1613749) | more than 3 years ago | (#34989484)

FTFA:

That compressed gas, stored at pressure as high as 5,000 pounds per square inch, represents energy waiting to be released.

Not sure I'd want to be an a 1.0 version consumer vehicle with that much pressure without some serious discussion about the safety precautions to prevent or mitigate "unexpected pressure drops". Can someone who's got more experience with the fluid mechanics add to this?

Scuba divers drive around with aluminum cylinders containing air at 3,000 PSI. Safety "burst" discs are built into the regulator of the cylinders so that if over pressurization occurs they rupture. The results are frightening and embarrassing but its only air and not shrapnel since the cylinder remains intact. I expect there are similar technologies in the pressure vessels in these cars.

Re:Scuba tank's burst disc ... (1)

noidentity (188756) | more than 3 years ago | (#34989668)

Scuba divers drive around with aluminum cylinders containing air at 3,000 PSI. Safety "burst" discs are built into the regulator of the cylinders so that if over pressurization occurs they rupture. The results are frightening and embarrassing but its only air and not shrapnel since the cylinder remains intact. I expect there are similar technologies in the pressure vessels in these cars.

And scuba divers have also been badly injured by defective tanks [google.com] that couldn't even hold their rated pressure. Apparently the tanks get regular inspections and tests as well. Want to trust that they used high-quality tanks in your vehicle?

Re:Scuba tank's burst disc ... (5, Interesting)

Ed Peepers (1051144) | more than 3 years ago | (#34989938)

Yes, SCUBA tanks (in the U.S.) are supposed to undergo annual visual inspection (basically an interior/exterior idiot check for bad rust, chips, cracks, beat up valves, etc) as well as hydrostatic testing every 5 years*. The cylinders most likely to have a catastrophic failure (typically the neck) were a bunch of aluminum 80's manufactured something like 30 years ago. Back when I worked in a dive shop we would do an eddy-current test on the necks of ALL aluminum cylinders during the annual visual inspection even though it was only really necessary for the one batch. If you take halfway decent care of a tank and don't let moisture get in (by draining the tank too low), they'll last for ages. We had decades old steel cylinders in our rental fleet that had probably outlived many a valve!

The concern is probably warranted but I would imagine the auto industry's safety measures will be far greater than those of the average diver. If the vehicles only go in for maintenance once every few years, the tanks ought to be fine. I would worry more about them being punctured during a collision. Frankly though, assuming they've done at least a minor amount of planning with collisions in mind, the severity of a collision strong enough to puncture the tank would make a sudden release of pressure the least of your concerns.

* Disclaimer: I've been out of the dive industry a while, my numbers might be off.

Re:Scuba tank's burst disc ... (1)

Anonymous Coward | more than 3 years ago | (#34989752)

They'd have to have burst discs, or the DOT would never certify them for use.

P.S. my scuba tanks are filled to 3500psi, you insensitive clod!

the burst disk guard can become a projectile (0)

SuperBanana (662181) | more than 3 years ago | (#34989824)

Safety "burst" discs are built into the regulator of the cylinders so that if over pressurization occurs they rupture. The results are frightening and embarrassing but its only air and not shrapnel since the cylinder remains intact.

Ask a dive instructor who is old enough, and they'll tell you about The Time I Saw a Burst Disc Retention Cage Shoot Through The Side Of Someone's Trunk And Through The Car Next To It.

Basically, the "cage" that "catches" the burst disc often is corroded or otherwise fails from the force of the burst disk hitting it with a couple hundred pounds of force. They break free and usually make it through at least two pieces of sheet metal before coming to a stop.

Also, burst disks are not 100% reliable, nor are the correct disks always installed. And yes, SCUBA tanks DO fail- usually when being filled, and they shatter. That's why scuba shops only re-fill tanks while they sit in containment vessels (the vessels also hold water, which helps with the heat from adiabatic compression.)

Re:the burst disk guard can become a projectile (0)

dfghjk (711126) | more than 3 years ago | (#34989858)

Do you know ANYTHING about scuba tanks? Apparently you haven't been to many scuba stores.

Re:the burst disk guard can become a projectile (1)

c0lo (1497653) | more than 3 years ago | (#34989916)

Ask a dive instructor who is old enough, and they'll tell you about The Time I Saw a Burst Disc Retention Cage Shoot Through The Side Of Someone's Trunk And Through The Car Next To It.

Also, burst disks are not 100% reliable, nor are the correct disks always installed.

So, don't use bursts disks, pick another (more reliable) version of a release valve (it's not like burst disks are the only way to do it).

Re:Which is a more dangerous battery? (0)

Sarten-X (1102295) | more than 3 years ago | (#34989578)

How about the team of fully-qualified engineers designing the system? Or perhaps the analysts who examine the results of crash tests before it's ever released as a consumer vehicle? If they say it's safe, will you take their word for it, or rely on the advice of a dozen Slashdot residents?

Re:Which is a more dangerous battery? (0)

Anonymous Coward | more than 3 years ago | (#34989622)

Compressed Natural Gas tanks hold highly flammable gas at 2900 psi (200 bar), they're proven technology, very well constructed and are usually the only thing left intact after a crash. http://en.wikipedia.org/wiki/Compressed_natural_gas

Perfectly safe, not reliable. (5, Informative)

SuperBanana (662181) | more than 3 years ago | (#34989782)

For those who are not into car repair et al, Audi used hydraulic pressure accumulators for power brake assist. It's a great system, particularly for turbocharged cars, which spend a considerable amount of time in normal driving with low or no manifold vacuum (which is created by the pistons trying to draw air past a restriction, aka, the throttle vane. That big round thing your brake master cylinder comes out of? That's the vacuum servo. It uses surface area to multiply force from the vacuum.) Citroen used the same idea to power the extensive hydraulics used in their famous suspension systems. Mercedes did as well for their cars which had hydraulic power windows (!!), door-closers, and suspensions. Nowadays, the idea of hydraulic assist has largely gone by the wayside, with auxiliary electric vacuum pumps used where necessary. It's a shame, because the hydraulic system had a HUGE amount of reserve; you could pump the pedal hard almost thirty times.

The reservoirs are lovingly nicknamed "the bomb" by enthusiasts and owners of mid-80s-to-early-90's Audis, strictly on appearance; they look sort of like a large-ish cartoon bomb. I have NEVER heard of one exploding or failing (in terms of the pressure vessel, say, by cracking) in any way, and they've been in use for almost thirty years.

The way they DO fail, very predictably, is via the internal bladder that separates the nitrogen charge from the hydraulic fluid. Eventually the bladder fails, or the nitrogen simply diffuses through the bladder. Also, hydraulic systems are pretty horribly unreliable; with age, everything rubber fails eventually. Citroen did a pretty good job of proving that too, but on Audis, pretty much all the hydraulic hoses eventually fail. The hazard, in this case, is that when this system fails, it'll dump gallons of very slippery hydraulic fluid all over the road. If you're lucky, it won't also spray it all over, say, your hot exhaust. Atomized oil is pretty damn flammable.

Another danger: with the Audi system, all you had to do was pump the brake pedal until it was hard, and the system was safe to work on. This system would involve higher pressures and larger quantities of fluid...and it would become a real danger for anyone working on the car to do so with the system charged, as fluid over a certain pressure will either break skin or worse. I imagine they'll develop an easy way to discharge it, but people are still idiots.

The thing is also going to be a total bitch in a fire; I'm sure they'll put a pressure relief on the nitrogen side, but even then, you've got 10-15 gallons of flammable oil to deal with.

I really don't see Chrysler having any incentive to make the thing more durable than Audi/VW/Citroen did. It'll be made so it lasts about 60-70K, and then you'll be looking at replacing a huge, high-pressure tank. Expect the hilarity 3-4 years from whenever they go on sale, probably sooner.

Re:Perfectly safe, not reliable. (0)

Anonymous Coward | more than 3 years ago | (#34989950)

Er, don't forget these are Dodges.

There is a huge difference between a Dodge owner and a Citroen/Audi/BMW owner. In education, driving skill, and literacy.

No Audi owner is going to mess with some type of oddball container in their vehicle, but a Dodge owner will randomly pull out a cordless drill or a Sawzall, chug a Bud Light or two and try to cut it open, to devastating results.

If you thought a high-voltage hybrid was dangerous (1, Interesting)

Megahard (1053072) | more than 3 years ago | (#34989294)

Try working on a vehicle with a 5000 psi tank inside.

Re:If you thought a high-voltage hybrid was danger (1)

Mashiki (184564) | more than 3 years ago | (#34989654)

I've seen tires from semi's explode, and take peoples hands, fingers, and critically injure them if the rim shatters along with it. And depending on the type you're only looking at 50-250psi. Voltages we can deal with, car coils kick out 100k-500k volts or more for ignition.

Yeah I seriously don't see this ever getting off the ground unless the container is designed to 'not' ever explode but in the even of a crash will only bleed pressure at a low level.

Pointlessly small amount of storage. (4, Insightful)

fluffy99 (870997) | more than 3 years ago | (#34989310)

The amount of energy you can store in a 14 gallon hydraulic accumulator is pretty small. Even if they're cranking the pressure up to 6-7,000 psi the energy density is around 50kw-sec/gallon or somewhere around the equivalent of a car battery.

Re:Pointlessly small amount of storage. (1)

inputdev (1252080) | more than 3 years ago | (#34989410)

How much does it compare to a single start and stop? If every start is assisted by the accumulator, the energy savings will accumulate over many starts.

Perhaps not so pointless (4, Insightful)

Caerdwyn (829058) | more than 3 years ago | (#34989440)

Perhaps not pointless. In the city, it's the start-stop aspect which is the mileage killer. Regenerative systems capture some of the energy used to decelerate, and use it to re-accelerate later. This is responsible for a large part of the efficiency of electric hybrids in city usage. I'm not sure if the hydraulic system described in TFA is linked to braking, or would by nature of its design capture energy during deceleration, but if so it would definitely help in city use. In fact, that may be the only place in which it shows gains, but let's not underestimate that. Most minivan use IS city use.

There is also the advantage that it's not based upon rare earths or lithium, which have their own political "sourcing" issues and their own limitations on how much is available. In short- to medium-term timeframes, that could be more important than ultimate efficiency comparisons with electric hybrids.

The safety concern is a serious one. Unlike present applications mentioned in TFA (garbage trucks, busses), there is much less structure in a minivan-sized platform to protect the pressure vessel. Anyone remember the Pinto problem [wikimedia.org] ? This is solvable, though it will require more structure (meaning more weight) to protect it. Overall, the hydraulic subsystem + the weight of the protective structure are probably less than the weight of the electric subsystem including its batteries, so that may be a net gain over electric hybrids, but we won't know til we see specs.

Re:Perhaps not so pointless (0)

Anonymous Coward | more than 3 years ago | (#34989672)

More completely it is the stop-idle-start that kills the mileage. It also pays to stop the engine burning fuel instead of idling. Also, existing cars can be and have been retrofitted with this pressure-storage technology to recover braking energy. It might be advantageous to also recover some waste heat energy into the pressure vessel.

Re:Perhaps not so pointless (0)

Anonymous Coward | more than 3 years ago | (#34989842)

>Most minivan use IS city use.

Prove it -- I don't know a single person out here in the boonies who doesn't have one; and we do about 4x the driving city-folk do.

Re:Pointlessly small amount of storage. (0)

Anonymous Coward | more than 3 years ago | (#34989466)

Dear GOD please learn about units. kw*sec = kJ. We gave you metric units to make life easier, please don't complicate them unnecessarily.

I don't measure mass in joule-seconds^2 per square meter, and I don't measure distances as 5 meters per second for 10 seconds. Why do you feel the need to measure energy as Power*Time when Power is DEFINED as (change in) Energy/Time ?

Re:Pointlessly small amount of storage. (0)

lgw (121541) | more than 3 years ago | (#34989586)

Dear GOD please learn about units. kw*sec = kJ. We gave you metric units to make life easier, please don't complicate them unnecessarily.

Didn't that French "metric" system surrender already? Any real man uses the Furlong-Firkin-Fortnight system. Energy is measured in Firkin Furlong^2 / Fortnight^2, or F F^2/F^2 (any real man knows which F is which!).

Re:Pointlessly small amount of storage. (2, Funny)

c0lo (1497653) | more than 3 years ago | (#34989606)

Dear GOD please learn about units. kw*sec = kJ.

Given the prayer, I'd say you have an unusual relation with your GOD.

Not pointless (0)

Anonymous Coward | more than 3 years ago | (#34989980)

The point isn't whether this produces a viable propulsion system. The point is what degree of compliance is demonstrated by Chrysler to future EPA mandates. An equally important point is how much EPA money will flow into UAW pockets.

Many crucial points there.

Why don't they spring for a... (1)

Anonymous Coward | more than 3 years ago | (#34989392)

...spring instead?

Re:Why don't they spring for a... (1)

PPH (736903) | more than 3 years ago | (#34989750)

... flywheel?

Composite, carbon fiber. They've developed some that turn into somethin akin to cotton candy when they disintegrate rather than shrapnel.

High pressure? (0)

Anonymous Coward | more than 3 years ago | (#34989398)

Wait a minute... isn't that why people didn't want hydrogen cars in the first place?

What about supercapacitors? Those would be much safer than high-pressed nitrogen. Just because it constitutes 78.08% by volume of Earth's atmosphere doesn't mean we should trap it inside high-pressure cylinders. What will PETG say?

Re:High pressure? (1)

cynyr (703126) | more than 3 years ago | (#34989678)

hmm short a super cap with some steel or aluminium bar, and let me know how it goes.... or simply ground one end to the car body and watch it light up a rescue worker/bystander when it ground through them.

Re:High pressure? (1)

mug funky (910186) | more than 3 years ago | (#34989692)

bugger the ethical treatment of gases.

i finally found a way to make popping candy!

when pressure cookers just aren't enough.

Re:High pressure? (2)

c0lo (1497653) | more than 3 years ago | (#34989730)

Wait a minute... isn't that why people didn't want hydrogen cars in the first place?

No, it is because pure hydrogen has a lower energy density the hydrocarbons and it's highly difficult to store hydrogen (the tiny bastard uses the pores of the steel container to escape). See hydrogen storage [wikipedia.org] .

What about supercapacitors?

Expensive like hell.

Those would be much safer than high-pressed nitrogen.

Would it, now? Just what you think happens when the hundreds of ampere*hours discharges through you body in the shortest time possible? Ah, you say: why through my body and not through the car's body? I ask you in return: why the nitrogen tank should explode instead of releasing all the gas through a "sacrificial valve"?

Just because it constitutes 78.08% by volume of Earth's atmosphere doesn't mean we should trap it inside high-pressure cylinders. What will PETG say?

Who? The polyethylene terephtalate glycol?

Re:High pressure? (0)

Anonymous Coward | more than 3 years ago | (#34989814)

Think PETA.

Techno bonus! (0)

Anonymous Coward | more than 3 years ago | (#34989448)

Your inflatable beach toys will be ready for fun in no time!

Re:Techno bonus! (1)

PPH (736903) | more than 3 years ago | (#34989714)

Your inflatable date will be ready for fun in no time!

There. Fixed it for you. (I like my women with hard bodies. But #2500? Sheesh!)

Re:Techno bonus! (1)

c0lo (1497653) | more than 3 years ago | (#34989748)

Your inflatable beach toys will be ready for fun in no time!

And the stout is so much smoother when using N2 instead of CO2.

Phenomenally bad idea (0)

goodmanj (234846) | more than 3 years ago | (#34989460)

I don't like this one bit.
1) Failure mode. All the energy is stored as mechanical potential energy, and will go right into kinetic energy in an accident. Batteries and liquid fuels have the huge advantage that when they blow up, most of the energy is released as heat. 100 kilojoules of thermal energy delivered to your body might give you a few blisters. 100 kilojoules of mechanical energy will rip you to shreds.
    Now, one might be able to hook an emergency dump valve to the airbag electronics, so it rapidly release air from the tank before the crumpling car causes it to burst. But are you gonna bet your life on that?

2) Energy density. Every calculation I've seen suggests that even with the best carbon fiber wound super duper air tank, the energy stored per kilogram is much lower than current lithium batteries.

Re:Phenomenally bad idea (1, Insightful)

hardtofindanick (1105361) | more than 3 years ago | (#34989592)

So, in short, you are ok with riding with 20 gallons of highly flammable liquid but you are afraid of 14 gallons of compressed air?

Re:Phenomenally bad idea (1)

goodmanj (234846) | more than 3 years ago | (#34989802)

Yes.

Re:Phenomenally bad idea (1)

IonOtter (629215) | more than 3 years ago | (#34989600)

Batteries and liquid fuels have the huge advantage that when they blow up, most of the energy is released as heat.

I dunno about you, but 99.9999% of the world's population considers that to be a very serious DISadvantage in an accident.

If the pressure cylinder can be held in place, then the sudden, explosive release of an inert gas, such as Nitrogen, might actually be of some value in an accident. Fire suppression, perhaps?

Re:Phenomenally bad idea (0)

omglolbah (731566) | more than 3 years ago | (#34989724)

Any release of that much pressure will cause some serious damage to anything nearby.

The problem isnt the cylinder moving, the problem is that if the structural integrity of said cylinder is compromised even a little it will fail catastrophically and spray shrapnel..

People dont think of pressure as a "bomb", but it really is...

Re:Phenomenally bad idea (1)

IonOtter (629215) | more than 3 years ago | (#34989918)

If the force applied to the tank in question is sufficient to cause a catastrophic rupture/explosion, then I would hazard to say that none of the parties directly involved in the collision are likely to care, as they're already dead.

Simply piercing the sides won't do it, you'd have to completely crush it. And considering the location and construction materials used, that's not going to be easy to do.

Re:Phenomenally bad idea (2)

Belial6 (794905) | more than 3 years ago | (#34989804)

I'm actually wondering about the opposite of most of the energy being released as heat. When you depressurize a small can of compressed air, it will freeze the can, as well as the object you are pointing it at. How much heat could a 14 gallon tank suck up if were to depressurize rapidly?

Turbo button... (0)

Anonymous Coward | more than 3 years ago | (#34989512)

I hope there's a turbo button that vents the nitrogen to a rocket nozzle for when you want to pass someone.

Re:Turbo button... (2)

c0lo (1497653) | more than 3 years ago | (#34989774)

I hope there's a turbo button that vents the nitrogen to a rocket nozzle for when you want to pass someone.

Only if your van uses a 486 CPU. After that, it's just nothing or adjusting your BIOS setting (which requires a cold-reboot most of the time).

Hard to jump start (1)

Anonymous Coward | more than 3 years ago | (#34989520)

So if I can't start my engine and my pressure tank is empty, how do I jump start it? Connect a high-pressure line from another vehicle with the same kind of accumulator? Or do I have to tow-start it?

Re:Hard to jump start (1)

gbelteshazzar (1214658) | more than 3 years ago | (#34989632)

grab the mouth piece and start blowing ...

Re:Hard to jump start (2)

c0lo (1497653) | more than 3 years ago | (#34989790)

So if I can't start my engine and my pressure tank is empty, how do I jump start it? Connect a high-pressure line from another vehicle with the same kind of accumulator? Or do I have to tow-start it?

Would help if you'd have had baked beans for the dinner a night before. Though... mileage may vary.

Compressed gases aren't *too* bad (5, Insightful)

slimjim8094 (941042) | more than 3 years ago | (#34989588)

I routinely work with compressed gases (~2500psi, medical oxygen on an ambulance). The tanks are tremendously well-built, and if you drop one you're worried about the valve because it protrudes - not the tank itself. And by my envelope calculations, there's something like 603k pounds trying to turn my tanks inside out.

Yes, I'd want to be damn sure I knew what that tank was doing, and how well it was built - but we're pretty good at making pressure vessels that won't rupture on their own, and equally good at making ones that are solid enough to withstand impacts.

Frankly, 15 gallons of gasoline worries me more. The kind of impact that would rupture a tank would aerosolize the gas, and I'd rather be in an explosion than an explosion with fire.

Re:Compressed gases aren't *too* bad (4, Informative)

S.O.B. (136083) | more than 3 years ago | (#34989736)

Finally someone who has something intelligent, constructive and relevant to say rather than the myriad of knee-jerk, living in mom's basement, I watch Discovery Channel experts.

Are you on the right site?

Re:Compressed gases aren't *too* bad (1, Funny)

seanvaandering (604658) | more than 3 years ago | (#34989908)

Is it discovery channel that everyone migrated over to? Dammit! I'm still watching "The Learning Channel" and learning that having 19 kids is suicidal.

I don't know when Chrysler started their project.. (1)

jshackney (99735) | more than 3 years ago | (#34989634)

I don't believe it's quite the same thing, but this group [www.mdi.lu] has been working on a similar idea for a few years now. Only problem is I don't think the latter vehicle would be so splendid in the snowy North.

Re:I don't know when Chrysler started their projec (0)

Anonymous Coward | more than 3 years ago | (#34989954)

The U.S. Post Office tested that type of drive in route delivery trucks in the late 70s. It worked great. It's the same type of drive used in fork trucks with a hydraulic accumulator added to the pressure side. There's a tank of hydraulic fluid, hydraulic pump, control valves, accumulator, hydraulic motor and return line to the fluid storage tank. They have over pressure bleed circuits. The only thing more realiable is a good dog.

When Reagan got in office it was discontinued.

They've solved some serious problems (5, Informative)

Anonymous Coward | more than 3 years ago | (#34989670)

http://en.wikipedia.org/wiki/Compressed_air_car [wikipedia.org]
The compressed air car has been under development for a long time. It shows great promise but nobody yet has been able to make a practical vehicle.

The advantage of a hybrid vehicle is that it doesn't have to store enough energy for a complete trip. In particular, it stores energy (thereby heating the engine) and releases energy (thereby cooling the engine) over a short period of time. The pure compressed air vehicle has the problem that the engine is permanently in cooling mode. If the engine is hot, because it has just been compressing gas, it is far more efficient. The longer it operates as an engine, the less efficient it becomes.

The advantage of compressed gas for short time energy storage is that the storage is simple and does not take much sophisticated material as compared with batteries.

People raise the problem of a tank of gas stored at very high pressure. The hybrid vehicle doesn't need as big a tank. Also, they've been working on this for a long time. The problem is basically solved. It isn't nearly as much a problem as a tank of gasoline.

Chemical battery efficiency is quite poor (0)

140Mandak262Jamuna (970587) | more than 3 years ago | (#34989760)

The typical chemical battery used in hybrids have very poor efficiency. It stores only 50% of the energy given and releases only half of the stored energy. The compressed gas battery will definitely have more or at least equal efficiency. Failure mode is not a serious issue. The mythbusters fired rifle rounds into compressed gas cylinders to simulate the climax scene of Jaws and got pretty undramatic footage. (And as usual they ended up packing it with explosives to satisfy the viewers who want to see things go kabooom!). Mechanical things are very well understood and the technology is going to mature a lot faster than the electrochemical research. BTW one of the promising new battery technology is based on molten sodium. BytheBytheWay sodium has this nice property of being able to explode when exposed to water!

I always thought the flywheel battery (flywheels spinning in a vacuum chamber, suspended in magnetic bearings, arranged in quads to cancel angular momentum) would have very high efficiency. UT Austin demoed one of these things to power a building size UPS and one able to accelerate a train from rest to 30 mph.

What we need is really electricity priced the way cell phone minutes are sold. Peak hour, off peak and night rates. Then there will be an incentive for people to buy these things to store cheap electricity at night and use it in the day and reduce the grid load on hot summer days.

Re:Chemical battery efficiency is quite poor (0)

Anonymous Coward | more than 3 years ago | (#34989976)

Electricity is already sold that way in some parts of the US. Where I am from, in the summer it is $.14 per KWhr during the day and $.04 KWhr at night.

Anonymous Coward (0)

Anonymous Coward | more than 3 years ago | (#34989766)

This was invented about 1970. The inventor was thwarted at developing his invention. He died of an apparent drug/alcohol overdose. How about a program to make arrogant suburbanites aware of how much they are wrecking the US economy with their SUVs and oversize pickups?

F1 KERS (1)

Kvasio (127200) | more than 3 years ago | (#34989778)

KERS [wikipedia.org]

Air Jammer, Road Rammer (1)

noidentity (188756) | more than 3 years ago | (#34989784)

The 1980s called and wants its air-powered toys [virtualtoychest.com] back.

Does it capture all the engine's energy at once... (0)

PinchDuck (199974) | more than 3 years ago | (#34989932)

When the head gasket blows? Yeah, Chrysler, HANG YOUR HEAD IN SHAME.

This isn't new tech... (1)

mlts (1038732) | more than 3 years ago | (#34989964)

Tata is making subcompacts in India which use this exact method as a propulsion source to get around. However, what works over there might not work over here.

But, if the technology makes it over, just the fact that it can keep a vehicle running with the gasoline or diesel engine off at idle to low speeds in city traffic would save a good amount of fuel.

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