Compressing Methane Gas

Where are you getting your methane?

Beans, lots and lots of beans.

Hi, what is 3500 psi in bar absolute pressure? From reading my manometer and a little calculation its in the neighborhood of 245 Bars. And why is it not liquified at this pressure? I assume temperature is the ambient 0-20 deg. C or so. Apart from that, safety must be a major part of designing a "compressor-plant-utility" so thats why it is expensive. And compressors have to be very high quality to make that pressure, so does piping, valves ect.

But I have had some thoughts myself about this topic, and this is what I found out.

regards

moe

It is well above the critical pressure for methane and cannot be liquified at any pressure.

Ive read Methane liquafies at about 3000psi. But I dont think this is really the aim is it?

What is the name of the compressor from England you refer to? Many years on the central east coast of Australia, A cocky had a large vessel mounted on the roof of his station wagon. Curious little boy I was about this I asked my dad what it was and he replied cow poo! Somehow he fed the gas down to the intake. But I suspect that it was a pressure regulated fuel supplement. Maybe even an early form of Hybrid in this country of that kind. At the time fuel was probably 15c/lt

Torncoppa

Sorry, should have said critical temperature, not pressure.

From memory, CH4 liquifies at around -140C to -150C at atmospheric pressure. Not sure of the critical temp, but it is well below ambient.

Hi, what is 3500 psi in bar absolute pressure? From reading my manometer and a little calculation its in the neighborhood of 245 Bars. And why is it not liquefied at this pressure?

3500 psi is enough to pressurize the gas down to a reasonable density for storage, but not enough to liquefy. that takes over 6,000 psi. Note: working from memory here. so, don't quote me on this.

propane on the other hand liquefies at 160 psi.

My two cents...

Storing natural gas at that pressure should definitely be done carefully. The storage system should be kept outside, away from power sources, and should be rated for the pressure. It also needs relief devices, which relieve up and away from you and your house.

You should purge the vessel before filling it. This can be done with an inert gas or with some of the natural gas provided you are careful.

I don't know what kind of compressor it would have, your home natural gas is probably in. H2O in pressure so the overall compression ratio is enormous.

Interesting thought. Elsewhere on the planet there is a reasonable market in LPG (liquid petrolium gas) vehicles, including aftermarket injection systems that run in tandem with gasoline. LPG doesn't need as much pressure as the density is higher, it's mostly propane + butane. If you can find a source of that it will be easier to compress.

CNG is also used in some countries, Compressed Natural Gas, which I think will be mostly methane. I can't help you on the compression side because it's already compressed at the gas station, the filler attaches to the vehicle using a pressure seal. I'll just mention that methane is only cheaper because the tax is lower!

And a bit off topic, but if you want a cheap alternative fuel, get an old rotary pump diesel and run it on old chip fat from your local fast food supplier.