Sawdust Gasifier

Hi fellow wood gassers
Does any one have plans for a green sawdust gasifier?
My mill produces about a ton of wet sawdust a day, this is a headache for many mills.
Now I was thinking if we could come up with a design and build a green sawdust gasifier, there would be no fuel processing just making a headache go away for a lot of mills.
I have been searching the net looking for some thing suitable, the closest I can find is the Missouri sawdust gasifier crossed with a Wayne Keith design.

Any thoughts or comments ?

Thanks Patrick

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Hi Wayne and Steve
Have you tried to build a sawdust gasifier ?
Thanks Patrick

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Hey PatrickJ.
I have a circular blade mill by intent so I can separate out mine into three grades: strands, meduim length like chainsaw chips and the smaller “dust”. Strands go to crafters or used for packging stuffing.
Meduim and fines go for the blueberries, strawberries, roses or outside chicken litter. Never have enough to go around and keep having to buy out for the inside chicken litter. Pony up and just buy the heat sterilized kiln dry size graded shavings for the inside chickens to keep the dust, mites and fleas down to minmum.
Wished you share me some. Other, bigger but still small mills here sell into these markets or use much for mud abatement. The big mills sell thier sawdust big time into the heating wood pellet and animal litter pellet supply chains, and to HDF and MDF board manufactures,. The big mills flip-flop for internal kiln drying combustion heaters to selling ouside depending on market conditions and source to natural gas lines. In the cold North always a market for heating fuels and wood mill wastes.

Regards wet and cold now until June now - then wet and warm until mid July/August
Steve Unruh

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Hello Patrick,

Sorry I can’t give much advice with the saw dust.

I did play with it a little years ago but kept coming back to wood blocks. Below is a picture of a coffee can with saw dust in a very primitive gasifier I was experimenting with. The heat from the char would force the gas from the saw dust and down through the char and I could eliminate the fines from clogging the burn tube. But like I said, very primitive gasifier (fema hybrid) and I kept coming back to blocks.

Also at one time I tried drying saw dust by filling a barrel with it and had the exhaust from my saw mill peculating up through it.


Hi Patrick,

Currently working on an idea, triggered by Steve of course, in the first idea - design - level yet, but has some potential.

Take a look at it, an give me some feed back.

The soul idea is at this stage to find out " could this function" and if so what would be the best configuration.

Replace the words Rice Husk with any other bio mass on the drawing.



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Hi Steve
Thanks, lucky that there is a market for a by product like saw dust.
Here we are to far from town to have any thing cost effective. Even the furniture manufactures in town have not got a use for sawdust. They have to pay to take to the town land fill.

Hi Wayne
Thanks in your opinion which would have more success for wood gas FEMA or a Missouri style ?
Or do I try a fluid bed / up draft system?

Hi Koen
I’m not sure I follow you drawing.
How does the rice husk /saw dust get in to the fire tube?
Then what stops the fire from migrating back to the air inlet nozzle ?
Have you had a look at the Missouri sawdust gasifier design, it’s very similar to Wayne’s just no heat exchanger but still working with a down draft system?
Do a you tube search on fluid bed gasifier and have a look at some of the designs that guys are trying.
I do think that we are both trying to gasify similar materials in the consistencies and particle size, rice husk may have a higher silica content so you may have to keep the gasification temp down as not to form lumps of slag /glass.

Thanks patrick

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why not make or purchase a press and make pellets…easier to gasify…and burn

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Hi Dennis
I have looked at that option as well, I was just trying to go with KISS system every sawmill produces sawdust so build a gasifier to gasify wet (green) saw dust with no or little processing, may just a little screening.
Less machinery to maintain and operate, less labour, all of that comes in to play.
I have had a lot of people come and look at my mill powered by wood, and a very common question is can you run on sawdust?
So this is what I’m exploring at the moment.
Thanks for the suggestion keep them coming, I’m really looking at this system.

I think a hybrid of the WK system and this may work.
Pree heated air and a well insulated fire tube. I’m going to give it a go in the next few days, work permitting.
I will start with a batch load and move on to a continuous feed system, the devil will be in the monitoring the sawdust levels in the fire tube.
Any suggestions ?


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Hi patrick,
No the fire is not getting to the rice husks ( saw dust)
the walls from the actual charcoal gasifier ( middle ) radiates its excess heat to the rice husks
its indirect gasifying, not combusting
The gasses from the rice husks or any other suitable material, will mix with the air going into the nozzle.
it is not a balancing act , where the charcoal burns in the same rate.
It is possible to evacuate the charred rice husks or saw dust into a bunker and use it in a second stage as fuel for the charcoal gasifier.
Depending the use of the charcoal gasifier, it will emits more or less heat towards the material between the charcoal gasifier and the outer shell.
its more using the escaping heat into converting biomass to energy.
It does has some potential so i am going to give it a try anyway.

I see also possibility’s for recovering wasted heat from the exhaust gasses and some of the particles from the flue gasses ( using the feedstock as an exhaust gas cleaner )
The temperature in the glowing charcoal bed will act as an catalysator, reducing the overall emissions.

keep ya posted


"Hi Wayne
Thanks in your opinion which would have more success for wood gas FEMA or a Missouri style ?
Or do I try a fluid bed / up draft system? "

Hello Patrick ,

I think I would stay away from the FEMA system. The FEMA does OK for what it was designed for which is emergency use. If wood is reduced down to char and big blocks precooked and fill the gasifiers in layers starting with very fine char and working up to big blocks one can make do but there is no room for error.

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Hi Koen,

I am sure I read somewhere that rice husks are full of silica and will result in clinkers in the gasifier.

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Gary H. Koen is well aware of that fact (posted elsewhere) and is trying to find the “sweet spot” in temp that will be just hot enough to gasify them without making glass.

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Have you been following the work of Dr. Paul Olivier in Vietnam? He has developed a series of rice husk gasifiers that have burner flames that resemble those from propane stoves. Earlier, he was very excited about using the rice husks directly, but now I believe he is moving toward pelletizing them. His webpage is here:
Look on the right-hand side of the page and you can download a power point presentation on biomass gasification. (Rice hulls, sawdust, etc.) The download is large, perhaps 12 Mb or so, and it takes a while to show up as a power point document. This webpage is loaded with outstanding articles! He also built a house in Louisiana that used rice hulls as insulation. In another search, I discovered this morning that the Silica from rice hulls might be used to improve Lithium Ion batteries by a factor of ten. It turns out that a high temperature method (like in our gasifiers) is needed to get access to this silicon that is porous, and resists degradation.

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Great ppt Ray, makes me want to build one!

Ha! Ha! Fellows this is what known as topic drift away from the orginator’s, Patrick Johnson’ original problem/opportunity of having near a ton daily of produced band saw dust produced by his mills ELECTRIC MOTOR POWERED saws. He dosn’t need, or want heat - he wants to turn this wood products sawdust “lemons” now into usable “Electric Coolaide” lemonade.

PatrictJ. your successful WK copy system now up and useable electric producing shows you the sawdust fueled system selection solution.
You can search the NET. Do lots of patent searches. Find and follow up on an 1980/90’s Alaskan sawdust one-time woo-hoo sawdust system. Find the India and Nepal sawdust cabonization then wet slurry hand briquete “honeycomb” systems. And you are already aware and now seen and touched one of the Millions Gasifiers deep bed pack systems. And been aware of the very complex, power hungry to operate, fludized bed “Geek” systems that no surprise, surpize, surprize, ever seem to make it to deloyment.
Will any of these have the hours, the installed and actual IC engine running systems proof “Acid Tests” for your situation??
Just like you’ve found with your WK build for your log perimeter edging wood wastes as chunks, the ONLY system out there with these proofs in IC EngineS running time powering simply, directly IS this Missouri Sawdust Gasifer system of RayR’s.
Developed by a Millman, for Millmen, and for thier real capabilities and operating conditions.
Pretty simple solution set.
"And Damn Fool can make things overly comlicated, overly expensive and . . . " and, And, AND!
Take’s a real Life DOer to cut off all of whoop’ta’la’s, bells and whistles, and lean down to something real and usable TODAY.

Reards to all
Washington State Steve Unruh

Hi Ray
Very interesting ppt, thanks for the link.

Hi Steve
I have emailed Ray Rissler in connection with his sawdust gasifier, asking if he could give some guidance in the design of a gasifier.
As you say a KISS approach to design is always best.

Thanks patrick

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Downloading it now…
Tx for the linking and thinking …
I have many detailed designs already about gasification-rice husks, not the easiest subject :wink:
For a good reason, i like to try the concept pointed by Steve first…
It really leans to my current design and future idea’s…
The Kiss approach , as mentioned above, is my favorite to…
Thats the main reason why i use the Gilmore style as my cornerstones to build on…

Thanks all

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Have some “old” stuf

from India
Edit… this not belongs in this topic, but i can not delete or replace it.

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And bad news for Dr Olivier,… Did he copy this work in his own style ?

Remember the other topic i posted from the Charcoal motorbike ? he used the forced feed system from this setup
As you can read in this presentation, dated 2008, made in Thailand

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We just ran a 300 ford six genset on sawdust all day today here at our lumber mill. It was the first day to run sawdust only, and was much more cantankerous than with our normal fuel of shavings, but it can be done. And with the engine running we had enough extra gas to flare 4 - 5 feet. Big difference in flare color between shavings and sawdust, and maybe my inspection tomorrow will help explain that.
First thing you will have to do is dry the sawdust. Then briquette it. There have been attempts to gasify loose sawdust in the past, most notably the Missouri sawmill and the Brazilian sawdust stratified. The way I see it, on your best day gasifying can still be the proverbial bitch with normal fuels, so having to mess with the bridging problems and resulting gas production fluctuations of loose fine particle fuels would only be a nightmare…unless someone knows something I don’t. Sawdust briquettes work. Mixing the sawdust with shavings works better.

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