A modern Gas Bag car
 

Look here http://krisdedecker.typepad.com/.a/6...3c14970b-500wi

And to: http://www.aerocivic.com/imgs/aerocivic-top-2.jpg

Low-tech Magazine: Gas Bag Vehicles
Natural Gas Bus in Zigong, Sichuan

"Fish tail" would be sufficient to store 0.7 to one cubic metre of gas by visual calculations. Or to one liter of gasoline equivalent. Should any one check this on real example ? If fish tail is useable for 60++ mpg, storing methane in it should give 10-20 miles "free" miles.

For skeptics - if adding batteries for toyota prius to get 10-20 ev miles is good, this mod could cheaper and more efficient.

They use inner tubes in India for hand-tractors. Allows you to store at a higher pressure without spending too much on it.

I think the problem with the gas bag is, since it's unpressurized, it relies on the bag being on top of the car to work. The inner tube's natural tendency to squeeze its contents out through the filler nozzle would probably suffice, and give you more range.

I've found this concept intriguing... you could essentially create a backyard digester, fill a tube, and use it to run a carburetor-equipped engine.

Inner tire could be an option, but it is not made to hold any bigger pressure. And its shape is not aero at all. But plastic bag with rubber strips for deflating could be made to work, event for diesel engine.

Also - http://c1gas2org.wpengine.netdna-cdn...3/dolphin1.jpg

With such a shape of car and high efficient you could store enough gas for 100 miles.

The Dolphin ^^^ has 200 miles worth of *lead* acid* batteries, that weigh 1,984 pounds. Can you imagine how many miles it could go on say 700-900 pounds of modern lithium cells?

Which cost 5000 to 10000 usd. Or more, depends on technology.

You don't take the point. We could take a toyota prius, add to it plug-in kit with 2 to 4 kwh of energy which will add 100++ pound of weight, or we could add a bag in empty trunk of ~400 litres of capacity to hold 1.36 kw/h energy. Or make a boot tail to hold 1000 litres of gas to hold 3.4 kw/h of energy. Pure methane will give close to 10 kw/h per cubic metre, assuming engine conversion ratio of 31% it will give 3.4 kw/h of energy at the whells.

Why not just compress the methane and put it in a standard DOT propane/NG tank ??

You can't do it at back-yard.

When driving through Wyoming, I think the side winds would rip the bag off the roof.

Just wondering if you filled the bag from your house natural gas line, what would be the equivelent energy costs compared to CNG or gasoline at the pump?

A simple sketch.

http://i40.tinypic.com/205avbb.jpg

Just like plug in hybrid without cost and weight of batteries.

Mike can modulate his range thru the gas pedal of the aerocivic.
Driving a tad slower will instantly increase his range ;)

Storing CNG at near-atmospheric pressures in easily damaged tubes is ridiculous - and dangerous.

As for the first pic, that bag on the roof instantly doubles the aerodynamic drag.

These were desperate desperate solutions in desperate times, resulting in minimal range.

It is safer because - it has no pressure to explode, and it is outside of car.

First pic is not a modern solution. Modern is shown in a post above.

A safety test: http://www.youtube.com/watch?v=luAtON_hG_w

And my enspiration: http://www.youtube.com/watch?v=lrhlRIvNjTc

...the Hindenbergette?

Compressed natural gas is much safer than atmospheric pressure gas. For one your placing it inside the cabin. You will not be able to hear or notice any leaking gas allowing it to mix with air and ignite. Once that happens that cubic meter of gas in your hatch will ignite all the interior trim and seats.

A CNG tank like on the cng-civic can withstand bullets let alone head on car crashes. And will give you hundreds of miles of range.

You can do it if you want to. Just wait till a cop pulls you over and it gets impounded.

This seems like a lot of work for, honestly, about 2 mpg. I mean you have to get the methane from somewhere too, which means you may have to sequester it. This would not be a problem if you had a commercial kitchen (Scientific American covered this as a 3rd world energy source a few months ago) but I don't think you're going to produce a cubic meter of uncomp methane gas each day for your morning commute...

...unless you eat a lot of Mexican food.

I think if you could store it in safe container and had a good supply of it itd be worth trying. I mean why not? Isnt that the whole point of this forum to squeeze every last drop of fuel out of our cars and improve them as cheap as possible.

My thoughts on this would be to put the bag in a small lightweight trailer with a hard shell that could be shaped for aerodynamics.

Since your not carrying the fuel in the vehicle and with proper venting, the chance of a explosion is nearly eliminated and would be much safer if there were a accident.


Parking would be the only problem.


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At near-atmospheric pressure, the trailer would hold so little gas that it'd be pointless to tow the trailer around.

I'd be very surprised if DoT even allowed carrying natural gas in non-approved containers.

Wrong.
I know several guys with NG vans that fill from home.
House pressure is too low so they use compressors.
Not expensive either.

This also goes to the DOT regulations. It is illegal and very dangerous to connect to a vehicle any flamable substance in a non-DOT approved container.
This is why motorhomes must use DOT tanks, not the standard RV tanks. Same goes for NG/LPG carbed vehicles.

As noted above, atmospheric gas is more flamable. When taking hazmat training we learned the explosive potential of an empty tank vs a full one. Very cool videos, but I wouldn't want to be sitting near it !

As a logical note, you could fit quite a few cubes of NG/methane in the trunk of most cars. About like adding a larger batt pack.

Thanks for ideas.

Video of can explosion: http://www.youtube.com/watch?v=hbggOyesUoA

It does explode - because in a can we got a mixture of air and gas. Same would be if we fill trunk with gas in a car.

But same trunk fitted with flexible bag filled with gas is safe. Because it does not mix with air. We take gas from bag, bag collapse. Unless we make two holes and supply air to the bag.

Trailer behind car is good idea, but we could get same result with bigger boat tail as stadet in first topic post. It is outside of car too, and it is mean to be aerodynamic. But it is small.

why not have the bag float above the car. like a helium balloon then you wouldnt be carrying the weight. or would you.

Take a look at the picture in the first post, and think about what that bag does to the CdA of the car.

A balloon would pretty much do the same.

-soD

So if you were to go through all this trouble of modifying your engine to run optimally with this stuff (which it sounds like they had to do even with crude 40's cars), where would you get large quantities of methane gas? Would your car even be able to switch over to a different fuel on the fly?

CNG does sound like a much better solution. Can you modify a gas engine to run it?

You dont't need a mechanical modification in engine. You need - a mixer device for fer feeding correct ratio of methane and maybe ignition time fine tune for spark ignition engines.

For diesel you don't need to modify anything. It will run on dual fuel then gas is present, or run on single diesel then gas is not present.

I guess you'd have to do a VW diesel then because that's the only reliable diesel in a small US market car that I know of. If you have a MK3 Golf diesel I'd say go for it, but maybe it wouldn't work so well with VTACK or Geos (Suzukis).

As to where, the typical source for the Indian small-scale inner-tube bags is digester gas, fed directly to a venturi/carburetor.

It's pretty easy to make digester gas at home. All you need is an airtight drum filled with waste, some cow manure and water (absolutely no air) and a hose to attach that to your balloon or storage container. If you use a rigid storage container and want some pressure, you'll need a compressor attached to that, but if the gas production is large enough, you can also use that to power the compressor.

Note, I said bag (balloon or bladder). If the commute is short, there should be more than enough gas between fills. (refilling daily if need be)

The main points for using a trailer.

1. to allow a larger bladder than could be placed inside a vehicle.
2. to separate the occupants from the fuel source in the event of a accident.


Using compressed gas in a approved container however, would be the best thing to do.

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wouldnt you then require a hazmat cert just to drive your vehicle then and a sign stating what it is carrying?

Same difference - a balloon is at what 1.5 x atmospheric pressure maybe ?
It's not going to hold a lot of fuel.
Why introduce range anxiety to gas cars ?
Driven beyond their gas range, they'll need petrol.

The main point against it is weight.
It's going to weigh an awful lot of pounds for a ridiculous equivalent amount of gas.
That weight is going to cost some gas as well.
Hence ... why ???

That's a new one on me. lol

I wonder if they make a pill for that...???

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Adsorbed Natural Gas Technology Applications

Another approach for biogas storage. Absorbed natural gas storage.

There is also a discussion on this topic in another thread.

http://ecomodder.com/forum/showthrea...tml#post291312

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True. And better than EV. Also - I bought 1 liter of activated carbon for the experiments. Mine came from water filtering company.