Exploring Charcoal

Yup here is yet another charcoal topic lol

Ok so here is something Im exploring. Raw Sawdust mixed in with charcoal. There has been some talk about a sawdust gasifier. Well what if; we mix in saw dust with the charcoal? I did just this today and started with a mild mixture of roughly 8:1 ish. After the run the intake of engine adaptor was bone dry and clean. So next run Im going to add more!! haha!!

This brings up the charcoal grinder. The first thing I see, is we need to Sloooooo0wwwWW those grinders way down. Why such the big hurry?? Slow these things down and crank up the torque so they can crush the wood that has not been charcoaled. If this wood is torified and is minimal this added in the charcoal I don’t think will hurt a thing. Maybe the guys with more experience can chime in on that.

Another observation I dont have the dust problem on the cross draft unit like I do with the updraft versions. So I am no longer screening the fuel and am now purposely trying to clog up the filter. I think on this cross draft the dust is burning up on the top side of the oxidation and adding heat. By the time it gets to the core of the oxidation process its burned up to nothing.

Turbo charging is now back on my plate. With charcoal being so clean like NG clean I can now implement turbos and that will be happening soon!! Based on the Tractor I built I bet turbo charged charcoal system will well exceed a direct wood gas system. The current machine is not quite what I can get out of a direct wood gas system. But the piece of mind knowing my engine will start after it cools down is worth that tiny loss. lol

Also new is teaming the M-Series. I have now designed the M-1 Standard to piggy back the M-1 Max. The standard is simplified and can be added cheap. This does a whole bunch of things for us. One is you add fuel capacity. One unit doubles run time, add another it triples it and so on. Next with two units you can refill the gasifiers on the fly. If both units are equipped with shut off valves; you can shut one off, refill and or service the unit while the other one keeps the generator running. Open the valve back up and bring that one back online and now you can recharge the other unit for continues operation. Then lastly you can simply run larger generators or even a vehicle with teaming.


Something else to explore. High content high temp steam input for water cracking. So what is the limiting factor of how much you can inject? Displacement of the gas input? Too much steam > less oxygen > less heat available to crack the steam? If this is the case then a oxygen concentrator could eliminate the nitrogen allowing more oxygen and higher steam input.

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I was making charcoal inside a retort inside a wood fired stove . I could have cooked on the stove while making charcoal . I could have boiled water while making charcoal . Someone said something about baking bread someone said something about a pizza oven . I have wood chipper and use branches to fire oven . most charcoal makers , make charcoal from branches and break it into smaller pieces later . My first system was automated and could turn walnut shells into electrical power and was sold as something that could run on wood chips . It will do that . There is a lot of smoke and time to get there and the original automation would always fail . Because it was only run on walnut shells and it tared up on them .


Ok second run with sawdust mixture. This time I added more I dont know the mixture but will record the amounts on future test. So anyways restart from cold, generator fired up no issue at all. Took some time to get up to temp and full power, I processed more wood, running the 3.5 hp electric chainsaw, circular saw and chop saw. After that it was running good and strong so did a quick test running the welder. I can hardly run a bead with out saw dust and it will kill the generator eventually. Ran a bead running on this sawdust mixture and I have more power. The welder it out of shielding gas and it was turned up higher than I normally would running on any gasifier. So for the moment I would say I am getting more power with the dust added. Now turning it down and running shielding gas, Im expecting better results. Also the governor is no longer pegged out. So the carb is no longer running wide open like is typically running the way before.

I should note: I dont think this will work with an updraft charcoal gasifier. This needs to be done in a cross draft or down draft. The M-1 Series are both more like a diagonal draft.


Ok well I found the breaker on one outlet popped. This is where i have the charger plugged into. So the weld test I dont know is relevant, It may do this same thing without the charger plugged I cant remember if I tried that or not. I do know I have less power than a direct gasifier though.

Anyways just got done running this batch. The hose coupling at the engine was a little sticky. So there is a limit. Im going to try a 1 to 4 ratio. 1 part saw dust to 4 parts charcoal and see how that goes. .Another observation is the mixer valve position is slightly more open running on this mixture, so that is a good indication the gas has more energy density…

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Maybe charcoal absorbed some tars from sawdust and turned it into fuel?


Yup just like a normal gasifier does, that is the theory anyways. This diagonal draft gives it time to break down after oxidation to the time things get to the grate.


Hi Matt,
welcome in the wonderfull world of what can be done with charcoal :grin:
It’s always a matter of numbers:
How much “potent” gas can you get into the volume of one stroke, what is the ideal mixture for ignition and what is the perfect ignition timing for said mixture.
The less nitrogen and the more oxygen does wonders , if not miracles, but even more to taking in account are the volumetric efficiency of your engines ( how to make the engine suck in more easy by smart filtering and good designed piping ) and the proper ignition timing.

Injecting water does increase the flamespeed of your gas (more hydrogen)= less need to work on advancing the ignition. ( but also cools down your glowing zone, sometimes to much )
Injecting tar (from charcoaling process) gives more potent gas as it contains more methane/penthane and such after cracking in the glowing zone.

Benefit from crossdraft = less pressure drop over the fuel stack
but little more loss from heat wasted
The gain from less pressure drop was always put into work to increase the nozzle speed / increased temperature / less Co2 in the gas…

The last part is the Co2 in the gas: the less Co2 = the better efficiency / more potent gas to work with

The better you know how to create / maintain a glowing charcoal zone and how to put it at work, the better the final outcome.

As i stated many times before, its always the glowing carbon in each wood gasifier… and that carbon comes from RAW wood… A charcoal gasifier is just the second part/stage of a normal gasifier…

Oh yeah, try to ad some sawdust particles in the nozzle of a updraft charcoal gasifier, or some particles plastic, or… endless list…

How to test, the easy way ?
I use a dummy load, 10 KwH, with regulator, and watch the rpm’s of the engine vs the amps/volts/watts output, create a baseline for reference, then i start to manipulate…


The way I see things now especially now that I know I can mix saw dust in is charcoal is more efficient and practical for use verses direct wood gasification. The water drip and the added 25% saw dust mix back into the fuel I think now more than makes up for the losses involved in in the charcoaling process. Yes you lose a lot in that process but re coupe that and more with the water drip and adding waste saw dust back into the system.

As for the gas densities I unfortunately don’t have the equipment to properly analyze the gas. As for the cross draft units I build they are a deep diagonal draft system. So sort of a combination of a downdraft and a cross draft. The air jet is just under half way up the hopper. So is nearly centered, The gas then has to migrate down and to the back passing through the grate to enter a channel to bring the gas up to the filter. These units seem to have more power than the updrafts units I first started building. The gas out is cold on these cross draft units verses the updraft units the gas was extremely hot. The hose temp at the gasifier outlet running the 212 is nearly ambient temperature on a warm day and around 120* 130* F running the 420 cc generator.


Hi Matt are you still using the Spacer slot ring carb. Style air jet nozzle. In the hopper?

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No not on the M-Series. The Fusion has this but it is an updraft unit with a flash steam reformer chamber built into it. So it is similar to the pellet fuel reactor with the disc ring jetting. I have not fully built one yet but it is on the plate as it is a sold unit.

I see this great concept with the charcoal slowly moving down stream of the air jet. The burning lobe runs out of oxygen and the ash moves with the gases settling down on the bottom of the deep diagonal path going to the grate and through the grate on the bottom. With the Ash migrating down leaving charcoal on top with no ash in it. Gases have less restriction passing through the charcoal and a longer path to cool down. This saves height of the gasifer. It also prolongs the time for a clean out of ash. This is where my straight across fails, the ash builds up to fast. Great idea, and there is something new under the sun of the world of gasification. Your air jet? In the middle of the hopper like a Kalley gasifer with a cone around to protect it from burning up in the hot white glowing 2000 *f plus charcoal? This is what I am picturing my mind. If this is some new concept secret you are developing. Let me know, and I will stop with the questions.
This diagonal gasifier is great news. It is the solution I have been having with my gasifer. I just need to change the slope on my gasifer fire tube bed. The flat bed will come out and can be modified to slope downward away from the nozzles. Sweet. Thank You Matt.


Ok Matt, I just can’t help myself, with just a deep bed of charcoal in your gasifer below the nozzle jet, is the size of charcoal a little larger so the ash can start it migration path more easily down and across the gases diagonal path to the grate? This will give me about 6 to 7" more drop in my gasifer with out the solid plate in place for ash to go. this was dead space before.
In yours the nozzle area, I picture smaller grade size of charcoal for gasification laying on top. The larger charcoal becomes a grate of charcoal for ash to settle into. This method could easily be done with a barrel. The nozzle jet just below the half way mark on the barrel. The grate opposite the nozzle at the bottom of the barrel where a clean out also could be added and the riser pipe going up from there. The extra charcoal in the barrel becomes the heat shielding for the barrel. Ash ends up in the bottom of the barrel the area has many different paths for the gases to travel so there is no clogging problems and easy gas flow with no flow restrictions. Gases are cooled down traveling this diagonal path way. Very simple design. Almost no welding required in my mind. Loading it up with charcoal for the first time would require a lot of charcoal, but after that it would just require refill on what was used in the gasification production of making gas.
I remember someone on this site using a barrel with fire brick nozzle in the bottom and making up draft unit. And putting on the back of a minivan. He had to remove the barrel to clean it out though from the top opening, it was a salvage barrel I think. This was a up draft with the filt inside the barrel no cooling rack. He just piped the gas up to the engine. With a few modifications it could be a across diagonal draft gasification unit. With a external cyclone filter or bag filter. Boy this makes me want to almost get my body out there in this 30 plus degree f. Weather we are having right now and dig a barrel out of the pile. I only have a heavy gage barrel, I think the lighter gage barrels would be great for this. Boy have I passed up on some of those in the pass that did not have the top lid ring closer on them. You could put the famous WK lid and ring on top for filling and you are set.
I have not had breakfast yet and I have been burning lots of calories just thinking about all of this, time to eat breakfast.


I have no idea how i missed this post in December last year until this morning maybe i was busy un wrapping pressys , anyway sat here with my morning cuppa and decided i may as well show you what i did late yesterday afternoon when the sun started setting .

Yesterday was a hot 36degs c up here in the hills ,and decided it be nice to have a couple of steaks cooked on the barby in the evening ,so went outside to collect some charcoal only to find i had used up all my home made charcoal in the gasifier , all apart from one drum i had brought home from a big burn we had at the scrap yard and someone had left the lid off it one day and it got rained on , anyway that got me thinking about a downdraft gasifier again and how Kristijans 1 hour challenge to make a double fluted gasifier might be time better spent this evening when it cools down and we can go out to eat later on instead .

So with no workshop here and only a drill and some pipe work to hand i dug out a old 60 litre oil drum , it has two screw cap bungs on top , the smaller 3/4 hole i used as a outlet with a 90 deg fitting and the larger i used as the filler port for the charcoal , i did not have 2 lengths of pipe to hand for the fluted nozzles , so this is a no weld single nozzle downdraft simple fire .
Hardest part was finding somewhere to sit this thing so i could have the gas out pipe at the bottom and still connect it up to my existing filters , so easiest way was to balance it onto of my large 220 litre gasifier sort through pipe work reducers and flex hose to complete , gasifier build took 20 mins but finding pipes to fit and reducers took me a good hour at least !
I did not have enough room to get inside the drum and fit any kind of mesh grid over the gas out so hoping the outlet pipe does not get blocked off , well it did make gas maybe not the best or strongest flare and the engine would only run with the mixer valve nearly fully closed off , so that means it was sucking in air somewhere so when i get the chance i will go over and check for air leaks on the pipework .
Still not sure if the gas is strong enough till i rule out air leaks and the gas out pipes were getting far too hot , with a distance of 12 inches between the fluted nozzle and the outlet i am thinking it needs to be further away maybe , also i only drilled 2 x 8mm holes in the flute they will change if i need to reduce velocity or increase engine size , as i said though this was just a passing thought on a lazy hot Sunday afternoon .



Yeah right I didnt know it exist till just now. Oh wait!! I created it!! man getting old sucks!!!

Nice build!!


Haha l see you are having fun :smile: flare looks good to me!


Had another go with the drum and downdraft pipe nozzle today , i replaced a very old rubber hose that had perished due to age &heat plus constant movement the past 3 years , not too bad for a old car radiator hose . no more air leaks that i can find i also lowered the drum and piped it into my large gasisfier in take , so now the gas has a chance to cool down running through all the old charcoal in my 225 litre drum gasifier and out to the filters and then the generator .
Generator started and ran but for a while the revs were pretty low ,its an inverter generator and was running at the speed you get if you flip the switch to eco mode ,anyway it did come up to speed after 5 mins during that time i played with the pipe nozzle turning the direction of the downward facing holes at the 6 oclock position towards the 9 oclock and 10 oclock to see if i could give the gas a longer path to go before leaving the drum , dont think it did much other than heat up the very top of the drum !
Tomorrow i shall pull the pipe out of the drum and drill the 2 holes to around 12mm each as i have a feeling i need to reduce the velocity maybe help cool things down some more , this generator normally runs fine on a 25mm nozzle
Once i can get this to work as nicely and reliably as my everyday updraft simple fire i shall find a 225L drum and see what can be done with that .


I am getting old so I can’t remember if I asked this before but how far down near the nozzles can you let the charcoal go on this downdraft setup?

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Ha! Ha! Of course most will focus on your charcoal results and completely overlook that you DID make some charging Watt-minutes on your first try!!

Because you used your “I don’t care about RPM’s” inverter-generator unit.
From 1974 with auto alternators being small engine belt driven I have ALAWYS had some generated charging watts, whatever the fuels.
And now with factory inverter-generator units we can have super electronics safe direct-use watts.

I will never, ever waste one more minute of my time on synchronous fixed RPM AC generators agony. Sell 'em off. Run them out to scrap.
And get on with the 21st century easy solution. Engine driven inverter-generators.

Good on you Dave
Steve unruh

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Hi Don , i’m not sure if i read you correctly are you meaning distance between the nozzle and the gas out pipe ? if so then i have no idea at all what is the correct distance i am just guessing , I am turning a simple fire upside down so as with my updraft to get cool and rich gas i need as much on top of the nozzle as possible to extend run time and to help keep the gas nice and cool , but once its used up and i have around 12 inches of char covering the nozzle i then start getting hotter gas out and it then starts getting weaker so its time for a refill .
I did notice in this set up it took much longer to get good burnable gas at least 5 mins of pulling on my fan on fresh charcoal , if that was my updraft it would be burning well in just around 1 min and maybe 3 too 4 mins on older charcoal .
This is why i am sure i am not in the sweet spot yet as Matt 's light up time is faster and plus he has cool gas coming out from his downdraft /crossdraft unit i can only hope to be somewhere close after many alterations to depth and distance but then again i am dealing with a basic tin can with a pipe and 2 holes in it , if it needs forming inside with baffles or deflectors then it means moving on from junkyard tanks to purpose made one perhaps .
If you meant how close to pipe/nozzle is the charcoal then it is surrounded by charcoal completely all around
Dave .
Steve i agree 100% inverter generators are the only way forward on small scale power setups , once running i do not lay a finger on mine for about 4 hours normally , if i ever hear the engine start to hunt up and down i know it needs more gas as power demand has risen above the normal 50 amps dc charging current ,i can tweak the mixture slightly or maybe just wait a min or two and let the system sort its self out as it usually does once its got over the shock of having to work harder .