New use for charcoal gasifier

Hello, all. My name is Bill and I can’t tell you how much I appreciate the work you pioneers are doing with Gary’s charcoal gasifier. And Gary’s decision to open source his design and freely share it is a testament to his moral character. That more than anything impresses me and gives me hope for the future.

Long story short, I’m working with a friend of mine on a gasifier that will gasify any feedstock that is gasifyable, not just wood. My approach is to use an external heat source to produce dirty, tarry producer gas, then use that same heat source to clean the gas up for the engine after it comes out of the chamber. I’m also incorporating catalysts to assist. My heat source started out as a rocket stove, but we wound up building a better stove to accomplish this. The catalyst to crack tar molecules is iron.

What does this have to do with charcoal gasification? Well, considering the high heat needed to clean up producer gas, I had to prepare for failure and find an alternative method to accomplish a universal-fuel gasifier. Failure is just not an option for my partner and I. And the research I did, just in case my original method failed, brought me here to the great work you all and Gary are doing.

My theory was that the dirty producer gas we created by externally heating a container of biomass could be cleaned up by running it trough your charcoal gasifier. The hot charcoal should be enough to crack the tar molecules into short chain molecules suitable to fuel an engine, if we filter it up through your gasifier.

Why do this when charcoal itself produces clean producer gas? Because a setup like I’m describing would allow you to make clean, engine-ready producer gas from wood, grass, weeds, plastic, used motor oil, waste paper/cardboard, animal/human manure, and agricultural waste, to name a few. The feedstock you can use would be readily available in most parts of the world and plentiful. We could stop throwing most of our trash into landfills and turn it into fuel to power our lives.

Until tonight, this was just a theory with nothing I had found in the history of gasifiers to back it up. I just found something to suggest this is possible, though.
Excerpt from what I found:

Perth, Western Australia, 1981. A Toyota diesel Land Cruiser fitted with dual firebox gas producer being tested. The unit has both an updraft generator for charcoal fuel and a downdraft generator for wood chips. The two are coupled so that gas from the wood chips passes through the burning charcoal and is purified of tars before entering the engine. For short runs, only the charcoal generator is lit. It is efficient, quick starting, and handles variable loads with little change in gas quality. For long runs, both fireboxes are lit. The gas formed by the downdraft generator supplements that from the updraft generator. The downdraft generator has three rows of air inlets (tuyeres). By unplugging the different rows a wide array of fuels and horsepowers can be accommodated. The unit shown was sized for use on an 8-ton truck.

This is a description of what I’m talking about. It suggests that it is possible to use your charcoal gasifier to clean up dirty producer gas made from just about any gasifiable feedstock.

Were I to try it this way, I would put a second container on top of the charcoal gasifier. A second set of raw feedstock would be in that top chamber. I would run a pipe from the top of that upper chamber to the bottom of the charcoal gasifier. I would pipe the engine exhaust into the top chamber, to push the producer gas into the charcoal gasifier. The waste heat from the gasifier should cause the material in the top chamber to off gas tarry producer gas. By the time it comes out of the charcoal gasifier, it should be clean.

I hope you all see value in this and pursue it.

Also, in my research, I came across another nugget you all might be able to use. Hydrogen can be a bigger component of the gas from the charcoal gasifier. You will need to add a little steam to achieve a more energy-dense fuel. Also, the catalyst to break the hydrogen from water is nickel. Perhaps a nickel screen in the gasifier which the gas has to go through would help separate the hydrogen from the oxygen. The oxygen should bond to carbon molecules in the gas. The additional hydrogen should help power the engine a bit more and ensure a clean burn of the producer gas in the cylinder. A small container welded to the charcoal gasifier, with a hole in the gasifier above the water line for the steam to enter, should supply the steam. Or, put wetter material in the upper chamber to supply extra steam.

Last, but not least, you should be able to make charcoal from materials other than wood. Bio-briquettes can be made from a multitude of things, like grass, paper/cardboard, sawdust, weeds, ect… (Look up bio-briquettes and charcoal bio-briquettes) When making charcoal, you might consider running the “smoke” through your charcoal gasifier, both to clean it up so it doesn’t pollute the air and to increase the amount of producer gas out of the charcoal gasifier. Either that or pipe it to the fire below the charcoal making retort. You can get the wood that is being turned to charcoal to partially fuel the flames in the charcoal maker, which should consume less wood during the charcoal making process.

Like I said, I’m attempting this universal fuel gasifier in a different way, but I wanted to share this with you all in the hope you find the info useful and it furthers your efforts. You all are doing fantastic work here. Just proves we don’t need those ass-clowns in Washington to solve our energy problems for us. If we want it done right, we’re going to have to solve it ourselves. So, lets get back to it.

That link will take you to the page I found info on the dual gasifier setup.

That link is to an account of driving across Australia on producer gas. It goes into the importance of adding steam to increase hydrogen content. Also, it mentioned the use of charcoal in his gasifier, along with an account of gasifying tire treads when wood was scarce. Sound familiar?

This is a link to a YouTube video that showed producer being made with an external flame. This is the video that got me started down this crazy gasify-anything rabbit hole. I wanted to put whatever material I wanted in the chamber, heat it over a rocket stove, pipe the smoke into a reduction chamber inside the stove, and get clean producer gas out. My plan has been adapted as I learned more, but the basic idea is still what I’m after.

I’ve learned a ton along the way and I’m sure I’ll learn a ton more before I’m through. If we all share info and ideas, we’ll accomplish big things much sooner. Keep an open mind and stay curious. Always watch to see what info can be combined and always pass along information to others who you think can use it. This is how we can get it done.



Welcome to the site. You’ve discovered several important things about gasification already:

  • Large amounts of hot charcoal will purify woodgas tars.

  • Charcoal is fast to start up and run.

  • Using the heat from charcoal making to cook the wood is smart and energy efficient.

  • Many things can be gasified, provided there’s enough charcoal,

  • Charcoal is best made from wood, most other things will not make a suitable char bed.

Now just put the two pieces back together, and you are close to having Wayne’s gasifier (there are lots of other details though). The Keith design has been called a “char bucket” type, which means it has a very large char bed. It can start quickly on charcoal, then as it warms up it will begin gasifying the wood. Anything that burns can be added to the fuel mix, but there must be sufficient wood to maintain the charcoal base. The heat from pyrolysis is shared with the drying and reduction processes.

Not trying to dissuade you from designing a new gasifier, just pointing out that these are already basic principles of regular wood gasifiers. It might be easier to start from a known quantity and work from there.

You haven’t dissuaded me. We’re already gasifying a wide range of materials using the external heat from our stove without the use of charcoal. I posted this because what you all are doing here will work to clean the producer gas as well, and from a wide array of feedstock. Fuel flexibility is something I see a need for, but not everyone would agree with that, especially folks who have access to plenty of wood.
Combining all the processes in one stand alone unit presents challenges with operating temperatures that running the processes separately using external heat does not, which is why I came here to share. Use whatever info you find useful, if any.
As for sticking to what is known or already has been done, if you read the first two links, you’ll find they describe what has already been done in the past with charcoal gasifiers. Some might find something of value looking into the history a bit to see how it was successfully accomplished back when this was necessary to ward off starvation. So much information was lost back when they stopped using gasifiers that we should be snatching any available information on the advances they made, so we can catch up to them. Be a shame to discount their innovations because they seem new and cutting-edge to us.

Good luck with your endeavors in charcoal gasification. There’s a lot of good work being done here. You all have my utmost respect.

Hey BillB.
No one here will try and dissuade you. It’s just for many if us have already been decades now down and back up out of this Gasify ALL “rabbit hole” you speak of. This is old hat stuff.

I have been involved with two different organizations that were into gasifiy Anything as a lead into GTL.
I/we have gasified coffee: beans raw, and spent grounds. Gasified corn: chopped up stalks, chopped up stripped cobs, and actual dried kernels. Gasified rice hulls, sugar cane “bagasse”, ground up weeds clippings, coconut husk. Had all different kinds of fruit pits thrown at us.
Unicorn poop (actually was deer droppings). Horse berries (poop). Chicken litter. Chicken poop. Pig; Cow; Donkey poops and litters/bedding. Refused to do the human poos.
And of course many differnt kinds of plastics.
And ANYTHING tree and wood products related like barks and cones whole and ground-up, and the re-densified forms of all of these.

Yep you are correct it all can be gasified.
And I will tell you it can be gasified in a downdraft one unit flow trough system without the complex multi clogging steps you promote.
But . . . . every catagory of input fuel stock will have it’s own system challenging in by-product waste left behind in the system and carried through in the fuel gasses.
The manures it is high mineral ashes, nitrates and corrosive byproducts hydrocloric and sulpher based. with a whole lot of silicates.
Animal litters some the same only much worse on the ashes and silicates residues.
All of the grain stems, leaf, husk grindings and husks themselves very, very high silicates ashes. Weeds are the worst silica contaminating stuff right up there with tree barks
These low temperature silicates at reduction zone char temps melt and glass like coat everthing, clogging and blocking gases flows exchanges. You have to chip these off later of all if the heat zone internal system, surface by surface.
Then gasified the actual grain kernels themself like corn, wheat, oats and rice . . . well . . . the starches cooking out makes for very stuck together gas impermeable sticky wads.

And it was these last actual food group fuels that put me over the edge. These were coming out of animal feed bags. We should NEVER be converting foods of any kind into mere into power.
Then I had to question, “Do we humans have right to rape the planet for a bit more power??” No we do not.
WE can choose whether to be just like sheep and goats that can rape a landscape down to dry sterile dust.
Like pigs, and chickens able to root up, and tear up every single blade of green and the underlaying root stock caplble of ever making any more green life.
Be like rats eating every single nut, seed to ever able to make any more green. Overpopulate and eating today with not a thought of tomarrow.

Naw. Sorry man. No sale here. I know it can be done. Seen it. I will choose NOT to go the Oppenhiemer route and H-Bomb develope just because I can. I will not be an Easter Islander riding the prideful master of the kingdon stupidity to bigger Ohh-Woww Idol making self-destructive oblivion.
A Norse Greenlander refusing to give up on favored pig meat and just eat whale and dress in seal skins instead of manufactured “civilized” sheeps wool.

Tree stem wood makes for the best of woodgas fuels and building materials. A forest is nurtued by US returning the leaf, needles, twigs and barks and in return the forest will nurture many others substainably.
Spent coffee should go to the worms.
Arborist ground up wastes make for the best of soils builders.
Manures ARE pure refined soil foods.
Same with the high mineral leaf, needles and twiggs.
Seed cones belong to the birds and the squirrels. Thier fuction is to spread these around.

The gasifiy ALL BioMass people can have the manmade plastics and municipal solid wastes to gasifiy to thier hearts content.
I will not be sharing my valuable wood charcoal to help out with this anymore. I will not share woodfuel knowlwedge to help drive us over the edge of having a good world left to upcoming generations. Trees grow back if nurtured and suppoerted.
For the unsustainable Urban wastes fuels, match up and use equally unsustainable coke converted fossil fuel coal for your Reduction zone beds.
This is dead serious advice to ALL BioMass fuelers - then your contaminates produced; that you WILL have to handle, will be similar and need similar cleaning up remediation. Quit hiding your toxic sins with clean woodchar.

All of course my own opinions that I have chosen to live by
Steve Unruh

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Gosh Steve, After reading this I was sooooooo… mad I went outside to kick my dog around. She was hiding somewhere so I ended up kicking a cement block along the drive way. After smashing it to dust with my bare foot, I feel better now. Quite the rant here but must agree with you in some areas.
Using food for power generation is absurd. There is an ethanol plant in town and every time I go by it I think about the EROEI (energy return on energy invested). How much fossil energy is expended to produce the ethanol? Most studies show one unit of energy into making the ethanol will produce 1.25 units of energy from the ethanol. Not worth it, but don’t tell the agriculture lobby. Same with any other food. It will soon be scarce enough as food production starts to declined due to increase in fossil fuel prices, ground water depletion and phosphorus production starts tapering off.
Your point about gasifying just about any material is spot on as is the need to tailor the gasifier to the intended fuel be it unicorn poop or plastic milk jugs. I can see a day when the landfills will be opened up and “mined” for the valuable products previous generations have thrown away. One of these items will be fuel and that means plastic. I just do not see how we humans will wean ourselves off fossil fuels unless it is a life or death situation.
Not sure where I am going with this post. Steve, you want to leave the plastics buried. Keep that carbon out of the air and use a renewable source of carbon that is wood. Agreeed.
Bill, a gasifier can be made to vaporize all sorts of otherwise nasty stuff and decrease our trash output. We are throwing away vast amounts of energy and putting it in landfills. Can we use that energy to transition to a way of life that is not dependent on fossil fuel or will we continue to squander that too?
Let me offer some encouragement for you to pursue your interest in gasifying other “stuff”. I can still remember the first time I dropped corn into the oxidation zone and watched it vaporize. I also have a 55 gallon drum full of BB sized plastic pellets. These also be used as fuel. BUT, I also understand that someday, this type of fossil fuel will not be available and the only thing left will be wood. That is why I am planting trees on the 30 acres of my property that was strip mined for coal 30 years ago.
Got to shut down my charcoal retort, so until later,
Gary in beautiful sunny, 70F, just had 1 inch of rain, everything is growing well, PA

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Ha! Ha! GaryG was NOT me saying we should bury plastics or even carbons. Please reread. I edieted for better clarity on these points.
I personally do not think we can stop the cascade to dig up every bed of recoverable fossile coal, drill and pump out every recoverable pool of dino juice. Can’t even stop the the marginal shale oil extraction. I think the lure of these already densified de-oxegernated dense relitivly cheap easy fuels is unresistable without a facist level of govermment/religious furvor that I certaily do not want to live with.
So much of this underground CO2 that has been locked up for millionas of years will be released back into an active CO2 cycle. Trees gonna’ love this. Be hard on the world wide coastal areas. Whole shifts in populated areas.

99.9% of plastics come from these petroleum and fossil coal stocks.
You betch gasifiy them and get them soonest freed up and into the active CO2 cycle. Illegalize plastics usege? Well maybe all that have chlorine in them. Just like 90% of prining now has gone from coal tar based inks to soy based inks.
WE would know we’d gone too far when we would here the commanded to use MORE plastics to be able to then supply a gasifer enrgy industry!!

As I said I will stick with the clean sustainable tree stem wood organics thank you.

Steve Unruh

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Hi Bill, I recommend throwing a dead cat in the hopper. Many of us have already run the gambit of throwing oil jugs (with oil), hay, leaves, pine cones, and other stuff in our units but the key is to have an active and hot reduction zone. The standard wood gasifier provides this provided it is started with a layer of good wood and the other crap gets dumped in intermittently. The idea of running the dirty outgas through a charcoal gasifier is a good one but remember that to crack anything will take energy and cool the charcoal gasifier down. The old town gas plants ran gasifiers in pairs. While one was stoking up it’s charcoal it would make steam to get cracked in the other one with the glowing char bed and then it would run out of steam and the charcoal bed would cool down some and they would switch off. This way they kept a minimum amount of nitrogen from being introduced into the gas stream … I only drove 20 miles today on wood and I just don’t think about it anymore because I know it works … I read 2 paragraphs and fall asleep … Welcome aboard … Mike L

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Dear Steve,

I stumbled over this topic, since i like to read a lot.

May i disagree on 1 important point; using wood, as an human, and consuming energy, will lead to an increase of green house gasses.
Let me explain better.
Letting the nature take care about our green waste by not converting that waste into something , is exactly the whole point, waste of energy.
The nature will transform , by natural decay, the green waste into carbon dioxide, methane and nitrogen. This is proven knowledge.
My opinion is as strong as possible, if you use wood, use all, including leaves, branches, really anything.
The three’s and the nature will thank you for that.
just turn anything into gasified energy and feed the ashes back to the nature.
Then there will be sufficient “three capacity” to convert an substantial bigger amount Carbon dioxide, which we produce by consuming energy…

Time to convert Carbon dioxide into fuel…

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Koen: I have to respectfully disagree with your “use all of the plant and return (only) the ashes to nature” idea. Soil wants fresh green waste to be added to it to help feed “fixed nitrogen” to the good bacteria in the dirt that breakdown natural waste into good growing soil. Without these good bacteria, nothing would breakdown when buried, we’d be walking around on a pile of broken rock, bone shards, rotten fruit and vegetables, and dead animal bodies.

Wood ash is just unburnable minerals left over from a fire. It is mostly Calcium Carbonate (bone, teeth, limestone, etc.) and Potassium Chloride, “potash”. These are both beneficial, in the correct quanities, to the soil for plants to use but only as a piece of the bigger soil picture. One isn’t “wasting” the green-waste, one is using it to feed more plants, which feed more animals, which can feed us.

From a woodgasser’s point of view, leaves and grassy plants are hard to gasify for several reasons. 1. They have a lot of surface area and stick together which blocks gases flow. 2. They contain a LOT of minerals that turn into ashes when burned, further clogging the gasifier. 3. They don’t contain much Carbon, which as you know is needed as a catalyst for making CO and H2 from CO2 and H2O.

Branches DO make good woodgas fuel, though I can’t remember exactly why. I think it might be that the woodgrain is generally tighter and more dense than trunk-wood?

Hey BrianH
Thank you for clarifing again the need to feed the soil so the soil can in turn feed more green growth and us.
Very true. I have traveled enough of the world to see the dry barren devastation from us and our animals when we get greedy, short sighted only one genration viewing. The dust bowls of the US and China as very real visible examples. Solutions? Was to plant trees. Lots and lots of trees. And now that the lands had been man and domesticated animal raped. Leave the trees there. Scotland, the mountains of Lebanon could have trees and forests again if there was the williness to do it. It has amazed the scentists in the devastated neighboring Mount Saint Helens area just how quickly with animals like bird and Elk with thier feces and seed introduction green Life is regenrating. Brian and I get to watch this in Real Time. Burn up soil potentualizers. Insanity!
Japan and individual areas in the Caribbean DID save their soils.
It is just so wrong, wrong, wrong to rape off consume everything. Makes us not sentient beings but just one genration to generation Locusts.

Every single long term generations sustainable human culture has always survived ONLY if they eveolve to giving a portion back to Mother Earth ethics. Those the did not are now pages in History. Or Lost and forgotton.
What shall we “moderns” be 1000 years from now??
What we do now and leave to the future determines this.

Bluntly, screw the Kalifornia Hollywood “Back to the Future” ethics of putting the banana peal into the car.
That is what people and domesticated animal undigestible wood is for!
Put the banna peal back active into the soil. My banna peals get there via chicken digestive guts bacterial potentialized!
Deep ground burial of soil enriching organics is even more insane tha burning then. Burning at least does put the molocules back into circulation for the next cycle.

And Koen: Brian and I do live in a “green hell” rainforest area of the world where we also have to contantly hack and cut back rampent green growth for each and every square meter of bare ground we want to maintain.
Brian my rule of thumb for the direction to tree use is if it will rot back in in 3-4 years it is Mother natures share. Tied up longer than that then mine to use. I use tree banches doen to 1/2" 13mm by that test. OK woodstove starting fuel and small gasifiers chunked fuel. I refuse to chip. Don’t want the machine maintance and fuel costs to chip reduce. Been there. Done that.

Steve Unruh

Brian, Steve,

I stated that if you use wood, should use it all. meaning following; where i live now, people cut the three’s to be used in the industry and or for energy. they don’t use the branches and the leaves and so on.

I have traveled the world several times, gave lectures and i keep studying pro’s and con’s. There is one hughe concern in nature: humans are tipping the balance and not in their favor…

if you use energy wisely, use resources careful, then you might change things

How to solve the increasing amount of green house gasses ?
How to find / to use other energy sources ?

I am currently teaching locally, to use normal crop and normal plants as bamboo, to be used as fuel substitute, did you know that you yield 5 times more bamboo from an acre then eucalyptus ?

Same thing goes for study’s about converting materials into liquid fuels and so on, rule of thumb: if you don’t ad a value then don’t convert…

Gasifying in retort kind vessels ( allotherm heating), gives a rich gas from any combustible ( also called pyrolising ) and yield 50% more energy in the same wood gas …

There is so much knowledge scattered around,… just combine and use it.

But i have to agree, humble, even my opinions are not the best, but just a point of view.

My moto: tomorrow we change the world but today we start with ourselves.

Using a wisdom i did read on this forum this week; think behind your borders…


Wow! I am a havn’t been doing this long, but when I read the very first comment of this thread I saw this coming. Steve, I read what I expected from you but did not see all things coming from all directions. Well, at least it is interesting. I will stick with gasifying wood chunks and branch pieces for what it is worth. Take care all! Dan