My first wood gasifier attempt

Hello, just found this forum a moment ago while browsing the web for gasifiers.

Wood gasification caught my eye about a month ago when i stumbled across an old swedish article about wood gasification during WW2. I was hooked and immediately knew i was going to have to try to build one.

Since i did not want to spend a lot of money i immediately started locking for material around the house that i could use to make this work. I all in all i spent less than bucks on this thing.

I quickly settled on a cross draft gasifier since that was the easiest to make with the material I had at hand. I used an old milk can as my primary reactor, and a smaller one for the filering. I used some 2 inch pipe as a radiator and an old blower fan that i found in my shed.

I finished building a couple days ago and fired it up for the first time today and it seems to be producing some kind of gas…

here is a picture since i am only able to add one :slight_smile:

I’d love suggestions for improvement since i’m obvioulsy new to these things.
Also, i tried lighting the gas on fire but the it just barely burns. and when i remove the lighter it stops burning. do you have any ideas to make the gas cleaned and more flammable?

This is obviously not the best design and all, but if you have any cheap suggestons for improvement id also really like to try them out.


Welcome to the forum!

Are you using raw wood? Cross drafts prefer lump wood charcoal as it’s fuel, or torrified wood.

The fact you’re getting flammable gas is encouraging. The lack of sustaining flare may be the fan pulling too hard or you’re not mixing enough oxygen in with the gas.

Did you check all your welds for leaks? I’m seeing on the vertical pipes some dark streaks that look like tar weeping out.


Yeah Id try running some charcoal in that baby. That is a charcoal gasifier all the way.


Hey welcome Daniel , hope this little setback wont spoil the fun your about to have , if i were you i would take this first build as a great learning curve , if you look at each and everyone of your joints where there is a trickle of tar running down that will also be where the air will be getting in and that’s not good , also tar dripping means one thing , your reactor is not cracking the tars and you don’t have enough heat in there and its allowing it to flow with the gas .
Save your self some headaches and start reading through some of the posts for small engine gasifiers for making power to start off with and get a feel for how others have got there systems working and then decide what you would like to run be it a car/truck or just stay at home power generator ect .
A day of reading will save you weeks of frustration in the end i think , still its fun learning .



Good job on your first attempt, and welcome Daniel. I agree with what the other members have said. Air leaks are important to get rid of. If tar leaks out then air can leak back in. When starting up you have a blower sucking vaccum on your system, this is what I see you are doing, good. Any air added after the gasifier has made good gases will weaken the gases and cause it not to hold a flare. To check this look at where the tar is coming out of the welds on the piping. The only air going into the gasifier should be at the nozzle intake valve. This build is a charcoal build and not a raw wood gasifier. Easy to make charcoal build a fire and burn down to charcoal coals quinch the coals in water. Let dry. I use my charcoal slightly damp 10% moisture in my charcoal gasifier. This will make more Hydrogen gases when running. Another way is to water drip water at the nozzle opening.
This will help keep your pipe nozzle from melting down in the high heat of 2000 to 3000 degrees f .
You are well on your way to having a DOW or DOC fun times ahead.


Thank you all! A lot of valuable information on here for sure.

Yes, this pipes leaks a lot. As you said already there are tars running down on the outside which is a bad bad sign :smile:

So i will fix that first. I only have a cheap crappy welder so even though i know how to weld it is quite challenging getting a good seal with this welder.

And also i was just using pine woodchips yesterday, and reading through your comments it definitly seems like charcoal is the one and only way to go.

I have never tried making charcoal before i think i will just pick up a bag at the store for now. When i know that it works i can start making my own.

Also, i was really exited to try the thing out last night so i might have rushed the wood preparation a little. My fuel kinda looked more like sticks than chunks to be honest :smile:


As an absolute final resort for sealing, in areas that don’t exceed 500 degrees F, use some Ultra Red RTV and aluminum duct tape. Apply the RTV and then the duct tape to protect it. If it gets in the 600 degree range the RTV will burn and if the engine sucks it up it’ll mess it up.

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Nice, good to know. I will try to grind down and reweld today, but if that doesn’t cut it i will try that.


Also for your fuel, here’s an easy method to make charcoal.

The tilting of the barrel makes it go by a lot faster. When you’re filled up with coals just put on a lid to snuff it out. I use a piece of sheet metal with bricks, it doesn’t have to be 100% airtight to smother it.
Don’t drill any holes in the burn barrel.

Wait about a day for it to cool off and you can crush it down by stabbing into the barrel with a shovel, and separate the big pieces and dust. Gary Gilmore has suggested a range of 1/8" to 3/4" so you could use window screen to sift dust out and some rabbit wire to get the big pieces out.


Thank you alot! That will be helpful


I ran it again just a moment ago, still on the same old wood as yesterday. Only it had becabe black and almost looked like charcoal :slight_smile:

However, last night it was dark when i tried it, and so when i looked at the flame today i could see that it did not even burn as good as i thought last night. I assume that the flame looked a lot better at night. As soon as the store opens i will go pick up some charcoal. And also i will try to weld all the air leaks when the temperature rises above freezing.

Meanwhile i thought i’d share a video from youtube:

This is the type of design that i have used inside the main reactor. And i re-watched the video today and noticed that he is able to get a sustaining flame and all while burning conventional wood? So what should i change on my version in the future to get it operating close to the one in the video?

Here is an image of my internal grate

And this is the gas/smoke i was able to produce :slight_smile:


Just don’t get charcoal briquettes. You want Lump Charcoal. You’ll save a lot of money making your own.


Welcome to the DOW Daniel.
When you store buy your initial WOOD charcoal you want real wood lump charcoal. Here it is sold as “Cowboy” charcoal. You will still have to hatchet chop that down to sieved smallish charcoal bits. Others will say what size.
DO NOT GET formed charcoal briquettes. They gasify very gas dirty from added combustibles like fossil coal powder. And will quickly clog your system from added clay binders. Open brazier use both of these and see this.

That video was a special no-weld project by the builder. He is very aware and knows how to build and operated true raw wood down draft systems.
He, as you should, would of had to pre-charge his system with real wood charcoal bits. Get that fired up good and hot Charcoal gas making first. THEN he could have added his raw wood chips. It would have worked some then too. Not long until the real charcoal got used up. Then the wood not hot enough at the edges away from the gas outlet failed to completely convert all of their heat released volatiles, leaving the cells walls char to continue to heat drive the system.

Those developing hybrid mixed system are all using some form of downdraft/downward material flowing systems. Read here KristijanL., Don Mannes, Matt Ryder, Dave of Dave&Brian.

As others are saying just use this cross-draft as a pre-made charcoal gasifer and you will do fine.

You still need to declare an intentioned engine powering use to get more refined advices.
Flaring is flaring. Stunting, entertaining. Proves little, to nothing. A distraction.
It is not system proof working. We are all engine working guys here. Engines powering is the standard proofs.
Steve unruh


back at it again :slight_smile: I sealed all the leaks i could find, filled it with charcoal and that made all the difference! I only have to flick my lighter once, and the flame lights up and burns nicely all by itself! I’m super pleased. I ran it for about an hour and refilled with my crappy pine wood as a test, and it still continued producing a really good flame. Tomorrow i’m probably going to try to make some charcoal for it. Based on my own poorly executed experiments i am albe to run on about 70% pine wood. As long as i keep some real charcoal at the bottom.

I have a lot of random engines laying around my yard, but i will probably use an old lawnmower for
experimenting tomorrow. I’ll run it for a good while and then remove the head to see if i have a cean enough gas to use on more valuable engines. My goal with this project is mainly just learning and experimenting. But it definitly would not be wrong to be able to run my generator on woodgas.

So, if i understand you all correctly the cross draft gasifier is a bad choise for me, if my ultimate goal is to be able to run my generator on pinewood. I have access to basically an unlimited amount of free pine, so i would really prefer that fuel source if only possible. I would be looking at an updraft or downdraft gasifier then?
Thanks for all the valuable answers guys!


all right, i will definitly take a look. I suspect i will be building down draft version very soon :grinning:


sice i live in Finland i really don’t know what those different variants are called in finnish, but i suspect you mean i should get the bigger ones?


Here is a Briquette, usually made from coal, charcoal, and sawdust and other materials.

For your gasifier you’ll find it will run better with smaller pieces. Also I wouldn’t blend more than 10% raw wood in the mix but that’s me personally.

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Ok, that makes sense now


Yeah, I don’t know how common briquettes are in Europe let alone a country like Finland but in the United States most people mean briquettes when they say charcoal. Most don’t even know about standard lump charcoal.