Forum Opinion: CNG Conversion

[Piotrsko]

Every lng/cng conversion ends up being a system to deliver X volume GAS. The compression/storage issue is to provide a small system to deliver that gas. If you could develop a low pressure system to store all the fuel required that would fit in your available space, them imho you are ahead of the issue and it is worth converting.

People have been doing this since 1975, some successful, some not.

[teoman]

Indeed, that was my reasonning.

One should already be using as little as possible (for personal transport)

And small quantities are easier to transport.

Ideally methane from biodigestion at a later stage.

[cajunfj40]

Hello teoman,

To get high volume of CNG at low pressure, look into Adsorbed Natural Gas. No, not "absorbed", specifically "adsorbed". Different phenomenon.

https://cenergysolutions.com/ has a fair bit on the tech.

Here's a commercial source of similar tech tanks, albeit not rated for road use (though they do state safe/rated to take around in a truck to get to a place to use them.) cylinders

[cRiPpLe_rOoStEr]

It would be crazy to do some makeshift with scuba-diving equipment in order to repurpose it as a CNG tank. I'd rather try a wood gas generator instead...

[teoman]

What is crazy about it?

A tank is a tank, a leak is a leak and a half ass job is a half ass job in both cases.

The tanks have dot rating. And a burt pressure of 200 bars. It is the compressor side that i am worried about.

The system is an order of magnitude more complicated than a liquid fuel tank.

PS: i do not recommended it to anyone who does not understand what they are doing.

[cRiPpLe_rOoStEr]

CNG tanks usually can stand to a 900-bar pressure, even though nobody would really want to try it... But anyway, considering that I'm aware of LPG bottles being used as a makeshift cylinder for scuba diving, and since LPG tanks are rated to a much lower pressure than CNG tanks, I wouldn't trust a scuba diving cylinder as a CNG tank.

[teoman]

Originally Posted by cRiPpLe_rOoStEr

CNG tanks usually can stand to a 900-bar pressure, even though nobody would really want to try it... But anyway, considering that I'm aware of LPG bottles being used as a makeshift cylinder for scuba diving, and since LPG tanks are rated to a much lower pressure than CNG tanks, I wouldn't trust a scuba diving cylinder as a CNG tank.

I have seen my fair share of ignorant people using cylinders way beyond their rated pressures.

A friend fills 300 bar scooba tanks (test pressure of 450 bar) for PCP (airrifle) use.

Once while I was at his house this guy came with an aluminium tank rated for 200 bars filled all the way to 300 bars. The real horror was the standard plumbing parts rated for 10 bars that he had concocted to transfer the gas!

Lpg tanks are usually rated to 20 bars with a much higher burat pressure.

[Piotrsko]

All this is rather extraneous if you cant aquire the compressor / system to actually do this.

Have we determined how much mass is required, and secondly, how big a space this storage has to be in? A 100 gallon tank is way different than a 5 gallon tank.

Around here I see stoopid people doing very stupid things all the time, causing me to doubt Darwin's theory of evolution.

[cRiPpLe_rOoStEr]

CNG might not be so cheaper than gasoline as it used to be, but it's still what prevents some old American imports from heading to the scrapyard in Brazil... Notice the underbody CNG tanks on this Explorer.

[euromodder]

Originally Posted by cRiPpLe_rOoStEr

It would be crazy to do some makeshift with scuba-diving equipment in order to repurpose it as a CNG tank. I'd rather try a wood gas generator instead...

Actually, the tanks are rated to similar pressures (250-300 bar)

And scuba compressors are actually used -in adapted form- in commercial at-home CNG-filling stations