wood gas info again??

[mikey ny]

hello,

   For anyone who is interested about wood gas storage, there is an intersting solution. I recenty e-mailed Tom Reed, the guru of woodgas, about any advance's made in wood gas storage. I am sure this is not "new technology" but he informed me that people, mostly farmers, are producing and storing woodgas in agbags. If you have ever driven through the countryside and saw those long white plastic bags in the field, they are normaly full of silage or feed for the farm animals. They are a cheap disposable alternative to silo's. Apparently some farmers are filling some of them with wood gas or other homebrew gas's. Sounds like a great idea if you have the acreage like a farmer has. I would imagine they must strap them down to the ground in some way or they might float away, Now that could be pretty scary seeing a 100 ft. long white agbag floating along at about 1500 ft above your house.

                                                  Mike

[DanB]

I've seen where folks use that sort of thing for storing methane.

Wood gas, as I've seen it - would seem scary like that because it contains enough oxygen to be very explosive on it's own.  Engines running off wood gas don't usually have an air intake, just fuel which is allready mixed, coming straight from the gasifier, and usually some kind of flame trap is required I think, in case of back fire.  The one I saw up here would occasionally backfire and everything between the gasifier and the intake would go off.  I could be wrong - it was a primitive gasifier that was running  up here, but it seems I read about that problem elsewhere.  Im not sure its the kind of gas you really want to store - you use it as you're creating it.  The vacuum from the engine forces the thing to create exactly the amount of fuel you need to use which kind of neat.

[bob g]

Hi DanB

there can be no free oxygen in the gasifier or it would oxidize (burn) the woodgas.

wood gas generators by there very nature starve out the oxygen so much so that they rob the water molecule of its oxygen atom which in turn free's up the hydrogen.

most if not all efficienct designs in wood gasifiers do not mix air (oxygen) with the fuel (woodgas) until the point of use, such as a mix control at the intake manifold.

as long as the agbag is deflated (no oxygen) and the gasifier is up to operating mode, there should be no admission of oxygen to cause an explosion.

so in my opinion, flamable yes, explosive no.

bob g

[DanB]

Thanks for correcting me there Bob - I double checked myself there and see that I was wrong.  The generator up here must've had a seperate air intake.

Here's some fun reading about it I found: http://www.fao.org/documents/show_cdr.asp?url_file=/DOCREP/T0512E/T0512e06.htm

[nothing to lose]

Well there are various ways to do anything of course.

Wood gas from a gasifier should not have oxygen. As air is drawn into the fire to burn the coals and create the heat which cooks the wood to produce the gas and all oxygen is burned up and that is the reason the gas produced does not burn. Now if you have a leak anywhere in the line after the gasifier of course you could suck in a small amount of air that mixes with the gas, that is not supposed to happen though.

 Even though the gas should not have air/oxygen in it I would use the flashback arresters. A pinhole in the side of a barrel above the firepot could allough air to enter the barrel and oxegen to mix with the gas but not burn if the gas has cooled enough. In such a case an outside source could ignite the gas and it burn back through the pipe to the barrel perhaps.

Now making wood gas with my charcoal maker is a different process. Wood is placed in a sealed barrel and baked with a fire below the barrel. In this case I am driving the air, steam, cresote, etc... out of the barrel and wood while it bakes but without burning anything in the gas. I am not certain, but I think I drive out all the air first as everything heats and steam from the wood begins. Now the question though is rather I am cooking out oxygen from the wood as well as the other items in the gas.

I don't think I am though. If I get the barrel cranking fairly well and lite a pipe over the barrel I have a few inches between the flame and the pipe. Myself I am just guessing but I beleave the reason for this is lack of oxygen in the gas to burn it and therefore it takes a second to mix with air in order to get the oxygen it needs to burn.

As far as the Agbags, sounds ok to me I geuss. But I wonder how they fill them and how they get the gas back out? I mean with the first gasifier it is normally the suction from the engine that draws the air through the gasifier for it to work and that means the gas goes into the engine and is burnt. Unless they use some other way to create that suction?

I have another thought also then for Agbags

If they are airtight enough to hold wood gas then I bet they are water and sewage tight also. If they don't leak gas they should not leak liquid right.

So maybe use them for somewhat of a sewage waste gas producer system. Fill with about anything that decomposes and connect to a pipe, as composting occures inside the bag you get methane gas to run an engine or burn for yard lights or whatever

 I should give that a try myself, but I may be leaving for a period of time again next week.

[Ungrounded Lightning Rod]

As I understand it, a major component of woodgas is carbon monoxide.  Close enough to the density of air (only 3% lighter) that it will stick around at ground level for quite a while if released.  Extremely toxic.  (In humans and animals:  Binds irremovably to haemoglobin forming carboxyhaemoglobin which no longer transports oxygen or carbon dioxide.  If you survive, full recovery of blood oxygen transport takes a month.  Other damage can occur, including brain damage, both from oxygen-starvation side-effects and other chemical reactions.)

Wood gas is why people USED to be able to commit suicide by sticking their heads in an unlit oven, and why there was a lot of death from accidental heating/cooking/lighting gas poisoning in the gaslight era.

Having one of those things spring a leak could easily kill anything downwind.

Your issue, of course.  (And your neighbors' if anybody is within a mile or so.)  But while I'm willing to store methane from plant digestion I'd only use woodgas in a direct production-consumption cycle.  And I'd recommend to anybody who insists on storing woodgas to use something safer - like a water/floating tank system - rather than a baloon sitting out in the weather.