Gas filtration with Charcoal?

Yes, when I learn something new in gasification I like to pass it on. The new cars and all the electronices that makes vehicles work is above what I want to learn these days now. Love the simpler OBD 1 and old stuff, yes the 60’s & 70’s cars rocked. Also I liked the under $1.00 a gallon fuel prices too.


Tom, maybe I’m a wimp, but when I read and see all that our wood-gas friends have to do and be conscious of in order to avoid taring up an engine, I retreat to the security of my updraft charcoal SimpleFire. For me, it’s best not to go there.


Yes Steve, the up draft gasifier is the easiest way to go. It is the lightest gasifier. You just need to spend a little more time processing the fuel.
I like the sitting alround the camp fire ring fellowshiping and hanging out. Like we do at The Argos Wood Gas Meetups. Just keep the wood piled up on the fire and shovel out the charcoal and put it in a air tight container water it down when done. Great engine grade fuel to drive on. The ash will migrate it way to the bottom of the flooded container.
I like it because I have large knots in my bigger cherry wood that I can not chunk up or slit. But I sure can burn it into charcoal easy. Small engines on cars and generators use charcoal gasifiers any type.
Just add water drip into the air intake and now you have almost the same energy out put that of the raw wood gasifiers.
But with out the tar and gooy mess that raw wood gasifiers operators have to deal with. Filtering is pretty easy too. Open cell foam, hay grass, wood chips, saw dust, damp charcoal, a bath towel, wool socks, wool blanket, to name a few and many more ways to filter it the ash out the same gases that the wood gasifier makes minus the tar. Learning curve much easier.
You can run bigger engines on charcoal if you do not mind have a tall high hopper for the extra charcoal you will need to go 50 miles down the road.


Back in the early 80’s when Morther Earth News started their gasifier builds I was very interested and would have build one then except their design called for hog hair filter media and never indicated that anything else could be used. Having no idea where to get hog hair I detoured to other things. I mention this because new people should know that nothing is carved in stone and adapting what you have laying around is perfectly acceptable whether it be filter media, or fire tubes. Some things may be better than others but use what you have until you can get better.


Yeah the hog hair thing perplexed me when I finally got my copy of the plans. I’ve never heard of animal hair being used for a furnace filter.

I think it’s a reference to how coarse the material is, looks like a scrubbing pad.

Might be something to consider coming in after hay in the bottom. Coarse to fine filtering.


Steve, I have to admit it hurts to hear people being scared off from raw wood gasification. I would like everyone to be able to experience the joy of cruising down the road on wood.
In my experience you only have to follow two simple rules. Make sure to run the gasifier hot until it’s broken in, and use only really dry wood.
Maybe one more. Don’t mess with the charbed. It’s like scab. If you keep scratching, it will never heal.
Other than that it’s nothing but refueling and cleanouts.


Well said Jan-Ola Olsson. Well said.
In addtion to your three basic must always do raw wood guideline let me add a couple of more.

For the smoothest ease of using raw wood; only woodgas IC engines larger than 1000CC, 35 cubic inches.
And only in those raw wood fuel woodgas engines with at least three cylinders or more cylinders.
This will give you the smoothed suction drawing for normal mixing schemes to work. With enough suction draw to make the heat to get the gasifier up good and HOT for minimal tars.
Oh yeah. You Must load the engines to actually make then draw. This is NOT RPM. It is power loading.

That now accepted guidelines of good wood gasification is 75% Operator and only 25% the systems hardware’s. Well that zooms up to 90% Operator when you try working with the really small single-, and double-cylinder pulsating cylinders engines.
I get that most do not want to invest into themselves to become really good operators. It is difficult to learn.

But get this . . . for those of us living in areas of the world where the conifer wood trees grow like weeds . . . and the rare good charcoal making true hardwoods tree is out of someone’s house yard or orchard. . . We Ain’t Got No Choice But To Use raw woods. And pitchy conifer woods at that.
Look at western Oregonian ChuckW. who’s taught himself to blacksmith with conifer woods. The Norse did.
Here in North American this use-raw-wood versus; just use easy charcoal distinctly has developed into a far West, versus anywhere East bias.
In Europe it is a far North, versus anywhere South bias.

And I’ll finish saying this . . . a real woodgas Operator can do both well. Why the fears to work to become the best you can be, eh? It is just a nuts and bolts engine after all. Falling down boo-boo’s are just part of the process of learning to be adult responsible and adult capable.

Steve Unruh


@sbowman you’re already brave enough to trust the idea that charcoal can produce flammable gasses to fuel an engine, and then put it in a small passenger car and drive it down the road.

If I recall correctly Steve has to rely on help with fabricating and welding, though all the brainwork and the non welding fitting was done by Steve himself. Utilizing Gary’s floor flange technique to attach his Flute nozzle and not need a welded joint. For Steve’s needs and what he has to work with I think he’s accomplished a lot.

If you need any help with building a raw wood unit let me know, Steve. I’m only a couple hours away.


Actually I’ve been using dog hair for filter media for a while now, Cody. After I made this video last year I added saw dust to the bucket ala Matt;R’s suggestion. It’s all simple, cheap and works well. No soot comes through. I should have made a follow up video of it hooked to the gasifier I built it for. The more I build, the simpler they become just as Gary Gilmore suggested when I first started.


Thanks for the video on a simple bucket filter for a charcoal gasifier.


Thanks for the offer, but I’ll stick with what I have. It works well for me.


Don’t feel bad. I just shake my head and think “why go to the trouble” when I see the complexity of what is being built to handle unrefined wood fuel, while I can get almost as much satisfaction from my much simpler setup.


I agree Steve. EddieR drove all over Argentina and I think a couple other counties on different kinds of bio-char. He seemed pretty happy and had the same smile the wood drivers get. Of course he wasn’t pulling a huge trailer load of hay like Wayne does. Wood or charcoal is not the same as real music or rap.


Steve, let’s just say I do get that part.
Trying to adapt to American conversation has taught me a lot during the last few years. I’ve learnt that even charcoal vs wood can be a delicate subject. I wonder if knitting would be ok to discuss :wink:

Tom, you’re a brave man.


I agree, the more back yard fires I have, the more I am liking the charcoal gasifier. And you are right it does not have to be complex, many have proven this with the simple fire builds.
Because I have the equipment and fabucating skills I build more complex gasifiers. But you have proven and others, you can get the same results I will say with a Great Big SWEM on your face Driving Down The Road On Charcoal. DDTROC or simpler stated Drive On Charcoal. DOC


I doubt they come down in price much. some of the super high heat refractories use really expensive metals like I believe it’s yttrium and halfnium. If you really want to try, the ‘cheapest’ option is probably to use a ceramic coating that you would use for like Foundries, forges, etc. And the super high heat ones aren’t cheap. :slight_smile: The only thing that I have seen that might suffice is the kaowool (ceramic fiber) blanket material which can go up to 2800F or 1530C, then you would still want to coat it to protect the blanket with a refractory coating.

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You can not fitter tar. When inside the gasifier filtration system; it is under vacuum and is in state of gas suspension until it reaches its due point. Tar is never produced as a single grade so like any refining process using a condensing process different grades produce a different products. Under vacuum some tars; when low enough temperature’s are achieved some tar variants will drop. But that is where the deception is, if you are making that grade you are most likely producing a grade that will not drop until post process. To filter a gas out of a gas requires extremely high micron level filtration and if you are producing enough tar where this level of filtration is needed it will clog it in a heart beat! So its really pointless. Look at the smoke coming out the flare or from a wood stove, a filter that can clean that will be way to restrictive to run an engine. A gasifier can and will have temperature variations as well. Tar can condense into liquid form when cold enough and then reform back into a gas when heated back up and escape the filter process. Ive seen this happen a lot! Best to use dry fuel in the first place. The filter system on a gasifier should not be to filter tar that is impossible. It is there to remove dust and only dust. If you are making tar, then you need to re think your system and build it so it is not producing tar. For small engines under 500 cc will be very difficult to get a small system to run stable. Tar production will be a direct result of an unstable gasifier. There should be a cooler to condense moisture out pre filter. Some grades of tar when under vacuum I now know due points are lower than ambient temperatures in warmer climates.

Ive ran machines in early spring and all was fine for a month of running. Take a break come back in summer temps and that thing is tar machine running the same fuel at the same moisture content.


Running the gasifier at variable speeds like in a vehicle where the rpms are changing from highway speeds to idle is the big problem. This changes the temps. in side the hot zone. With load generation the load is more stable.
Putting extra metal mass in the right places in the gasifer helps keep the hot zone really hot longer. On a gasifier unit this is good. And it is very important on a raw woodgasifier that makes the charcoal first and then uses it in the firtube and in the charcoal reserve on down to just above the grate or grateless area. Holding the heat up to the 2000°f to 3000°f in the tar cracking lobe area below the nozzles is the secret to not making tar and not letting tars pass by the grate area.
Any gasifier can make tar if not operated correctly in the proper heat range or not fueled with the proper fuel for that gasifier unit. Starting a gasifier up correctly is very important.
Having a good charcoal bed in place first will help to not making tar when starting a unit up. This is some of the other 75% of gasification learning and operating that if you are new to gasification you need to know and learn. How? By doing is the best way. Flairing and checking the flame for (raw wood gasifier) is good.
Not needed for charcoal gasification, but is fun when first learning and starting out.


It is 0 Farenheit in MN this morning. Anybody care to comment on experience with tar condensation in long cooling tubes in cooler climates?


Hi Matt! I am a newbie. How could you tell it was making tar? What did you observe?