Wood Gas

[Wisdom Bear]

Anyone know if you can compress wood gas into tanks for later use?

[bob g]

yes you can, however if you want to liquify the methane it takes something on the order of 5kpsi to get the job done, which consumes more power than is in the resultant fuel.

bob g

[Wisdom Bear]

Just thinking about a scuba tank pump. Would it compress enough? I think they mostly only go to 3kpsi.
But even that would put a lot more in a tank for later.

[madlabs]

Aside from the obvious dangers of compressing an flammable gas with a compressor designed for non-flammable gas...

You would also need to make sure you had very clean gas or you would gunk up your compressor. I have mucked around with wood gas just a bit, I made one crude one and briefly ran a small mower engine on it and am currently working on a GEK 4. Making wood gas is easy, making clean good consistent gas is not as easy.

I was thinking along the lines of low pressure large volume storage, like a large water tank floating inside a water tank. Still, most folks just make it as they burn it.

Jonathan

[gww]

Jonathan
How did you little motor fare on the wood gas?  Was it gummed up with tar?

Thanks
gww

[madlabs]

It ran pretty good, considering I was using a couple of valves for a carb. There wasn't much build up of tar, but I only ran it for maybe 60 minute total. I could see some in the delivery pipe though.

[gww]

Madlabs
This is on my list of wanting to build. 
Thanks
gww

[BigBreaker]

Wood gas is more than 50% inert nitrogen because the fuel is almost always gasied using regular air as the oxygen source and regular air is 78% nitrogen/ 21% oxygen.  The flammables in the wood gas are mostly CO and H2 - methane is usually a small fraction.

Compressing the inert nitrogen is a waste - it doesn't burn.  H2 and CO don't condense into fluid at room temperature regardless of pressure so you have to compress them like crazy to get any volumetric density.  As a bonus H2 always leaks a little b/c the molecule is so small and tends to embrittle many metals including high stength steel.  Basically it's a total waste of time for anything but a "buffer" tank.

If you really want to store wood gas you need to attempt the Fischer-Tropsch process which will convert the H2 and CO into a mix of hydrocarbons including liquids like diesel and near liquids like butane and propane.  Do-it-yourself Fischer-Tropsch would be an amazing feat.  Someone on the GEK forum seem to be making an attempt.

[DualFuel]

While Fischer-Troph would be a route to storing wood gas in a liquid fuel form...it has its issues. What to do with the liquid? It isn't diesel fuel, its wax, so some kind of chemical processing (like making biodiesel) would be needed. You do all that, but at some point you have to ask yourself, "what am I doing this for?"
My goal was to run the cook stove, the refrigerator, and have start up gas for the engine.

This was my gas plant setup. Lots of moving parts. The idea that it takes more energy to compress the gas and store it, then the gas contains is correct, but.... but if your battery bank is charged and your controller is just dumping the PV electric anyway, why not run a pump? The same imbalance can be said for ethanol fuel, biodiesel, and definitely fossil fuels.
Still after having done that. I found a non-electric way of starting the engine on wood gas without storing it. I also found that the new GE electric refrigerators are incredibly efficient (head and shoulders above propane) and that its still hard to beat the simplicity of a wood fired cook stove....so my need to compress and store the gas has slowly evaporated.
Its doable but why?
DF

[XeonPony]

personaly I'd sooner dump excess energy into cracking water and compres the H2 to 250psi and charge up some metal hydride tanks with it, now I got very very clean cooking fuel and furnace fuel as for genset diesel would be my number one choice as any oil will do so long as it is clean enough and the viscousity is right.

[BigBreaker]

Fischer Tropsch will make methane up to waxes and everything in between depending on the set up.  Generally Propane through Diesel is desired.  Anything shorter than propane is fed back into the reactor and anything in the target range is drawn off before longer chains can form.  It would be very hard to DIY though.  Waxes are generally not produced with iron catalysts.  The chains just don't get that long.  I think you use cobalt to promote the long chain hydrocarbons.  Again it's all about the setup - temperature, pressure and catalyst.

I reiterate that compressing wood gas is a bad idea, but the suggestion above about hydrolysis jogged my memory.  You could try injecting steam into your wood gas.  At the right temperature and pressure the CO+H2O converts to CO2 + H2.  Cooling the mix of steam, CO2 and H2 would condense the CO2 and water letting you draw off relatively clean H2 gas with very little CO.

If you just want to heat stuff... use the wood directly in a rocket stove or get fancy with an auger feeder.  Please don't compress wood gas.  It kills people - silently... or with a big explosion because O2 got in the gas stream.  Either way a bad idea.

[frackers]

Take a look at http://www.youtube.com/watch?v=yNr0MvHRYnM to see how to make clean woodgas.

You'll need to watch the video carefully rather than rely on the commentary which doesn't have a lot of detail (dumbed down!) but its all there!!

[madlabs]

I have access to a couple of small metal hydride tanks and plan to mess with trying to fill them through electrolysis. I don't actually hold out much hope for a reasonable cost, reasonable output system but I'm going to try. I have some experience with making hydrogen from a fuel cell robot project I did with my local high school.

Jonathan

[XeonPony]

I made a rather scaled up Hufman bridge style one using stainles steel mig wire to make my coils then a catylitic recombiner and such, the system did suprisingly well, untill it was dropped that is!