Woodgas Storage

[renewablejohn]

Any suggestions for storing woodgas.

I have found a wood gasifier with an inbuilt fan which produces a constant supply of woodgas. I intend to use this gas to run a generator during the day and provide additional heating for the polytunnels at night. To smooth out supply I intended compressing the gas in old propane bottles but finding a suitable compressor is proving difficult.

[Amy]

Preferably one which isnt going to ignite the gas, maybe a diaphram type compressor and stuff the gas into a propane cylinder?

[rogeriko]

propane bottles hold low pressure liquified propane not high pressure compressed gas, be careful

[Countrypaul]

Woodgas comprises significant amounts of CO and H2 along with other gases, N2, CO2 etc. Storage of H2 can be difficult and storage of CO can be very dangerous. CO can be readily absorbed by some metals, most obviosuly be Nickel, the resulting combination is relatively stable, but can release CO - and has been responsible for several deaths where the atmosphere was tested clear of CO only for more to be released later. Be very careful if you store CO especially under pressure.

Iirc during WWII they used to store it in bag canvas bags ontop of buses (not sure it was wood gas, may have been from coal).

Paul

[knighty]

iirc, Ivan has a compressor for natural gas ready to convert his car from LPG to natural gas  (I think?)


maybe pm him if he's missed this thread ?

[renewablejohn]

Actual woodgas analysis can be found at the end of the article

http://www.stakproperties.com/index.php?p=3_3

[Baz]

Commercial freezer compressor?
How many m3 do you need to store?
How about silage bags? If there is any air remaining in the gas it might be safer if it wasn't compressed in to a metal can.

[knighty]

a freezer compressor would cause an explosion if there was any air mixed in with the wood gas....  the only reason flammable refrigerants can be used is because there's no oxygen in there for it to burn!

[mespilus]

Woodgas comprises significant amounts of CO and H2 along with other gases, N2, CO2 etc. Storage of H2 can be difficult and storage of CO can be very dangerous. CO can be readily absorbed by some metals, most obviosuly be Nickel, the resulting combination is relatively stable, but can release CO - and has been responsible for several deaths where the atmosphere was tested clear of CO only for more to be released later. Be very careful if you store CO especially under pressure.

Iirc during WWII they used to store it in bag canvas bags ontop of buses (not sure it was wood gas, may have been from coal).

Paul

Yes,
Ludwig Monds' leaking valves gave rise to the
whole field of metal carbonyls:

http://science.howstuffworks.com/dictionary/famous-scientists/chemists/ludwig-mond-info.htm

[Ivan]

The energy density of woodgas is VERY low - 5000 - 6000kJ/m3 (compared to methane at 40 000kJ/m3)

This will mean it is very cost-ineffective to compress it for storage. Even with natural gas, if you compress it to CNG pressures (200bar), the electricity you use to compress it is equivalent to 10% of the heat energy of the fuel itself (and electricity is gennerally worth twice as much as heat energy). On that basis, if you compressed woodgas to 200bar, then the energy required to compress it to 200bar would be 80% of the energy contained by the gas, and if your CHP system was 50% efficient (it's not likely to be better than 25%), then you'll use more fuel to compress the woodgas than you've stored! If you store woodgas, the only real option is big plastic bags.

I have got a CNG compressor, but haven't yet got it plumbed up and working. I certainly wouldn't advise using a compressor for woodgas unless it's cheap - because the gas is quite corrosive (I think there's some ammonia and some sulphuric acid), and this would probably cause early failure.

[dhaslam]

You don't need to invent anything, it has already been invented.

http://en.wikipedia.org/wiki/Gasometer


Making  one might be a bit a little difficult.  Just two round plastic tanks,  one a little bigger than the other?   

[billi]

The french guy Jean Pain ( compost heating ) stored his Biogas in tractor tyre tubes  and put  weight on them to get the pressure for his gas cooker

Billi

[renewablejohn]

The french guy Jean Pain ( compost heating ) stored his Biogas in tractor tyre tubes  and put  weight on them to get the pressure for his gas cooker

Billi

This was the method I was going to use for low pressure using tubes inside an IBC container and then fill the IBC container with water to pressurize the gas to get it out. The only problem is finding a suitable compressor but surely its not as simple as a tyre compressor. The need for high pressure comes in running vehicles I saw Jean Pain running his car but the gas was not woodgas as it was derived from AD so will have a different chemical composition. The only other way is to purify the woodgas prior to storage but I am not a chemist and have not found any FT plants for this scale of operation.

[Baz]

Having looked at the video it doesn't seem to have any control system so the composition will be variable. The site didn't mention the N2 and CO2 that presumably are the missing 60%. Without a careful air supply control there will be varying amounts of O2 still in there. I don't think this matters for direct use as both the stove use and IC engine are going to mix a lot of air in anyway. The flame speed and normal venturi on a stove prevent, mostly, any chance of back ignition into the device. Likewise an IC engine isolates the ignition point.
I'm not sure if plain compression ignites either CO or H2 at the pressures you might use but as Knightly points out it is something to check.

[Countrypaul]

Purifying woodgas won't be easy as Nitrogen which will be the main component of wood gas won't dissolve in much (unless at high pressure). You could capture the CO using Nickel (as mentioned above) and release it by heating, but before you have done very much your energy input will be higher than the eventual output. If you used pure oxygen to feed the gasifier rather than air, the resultant woodgas would be much more useful with a much higher energy content, but the dangers increase and teh energy to produce the pure O2 would not be insignificant.

Paul