Woodgas byproduct

So Im totally new to this and seeking advice …simple question…when all the woodgas is produced and burned out,what is left afterwards?biochar or just plain ash?

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Welcome mike, If there is no leaks, you will have mostly char.


Thanks for that …what’s ur mass to by product %? Let’s say u put in 100lbs of wood…how much biochar/ash would u get out after?

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every system is different My modified WK Gasifier if I run about 2500 lbs of wood through it I might get 3 gallons of char that isn’t used. but I pull really hard on my gasifier.

Generally its 15%

I am working on a system that will produce biochar for both agriculture and power generation. This combining heat and hot water production with the char coaling process first. Biochar is then the byproduct of this stove and can be produced more in mass as its not as critical in direct wood heating. This stove basically produces fuel for your gasifier unit with little efforts required by the user. Access can then be used for agriculture or you can produce specific for that purpose.

Thanks Matt.
All of mine have produced way less than that. Thanks for the Info.

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On my Ranger short trips I will get about 20% char to raw wood, but I drove it to Ind. 400 miles used approx. 250lbs of wood, produced maybe a gal.


Welcome Mike; What Al said is true in the real world. The theoretical world is you start with wood and end with “ash”. If you put in 100 lb of wood— when strickly making charcoal out of wood, you end up with about 1/3 the VOLUME of what went in. I am not sure about the weight but it will be considerably less than a1/3 rd. the 100 lb. After the making of the charcoal in a gasifier, then the process removes a lot of the carbon (the “C”) out of the charcoal. Thus you end up with much less char than the volume of 1/3 of the 100 lb of wood. Something between the 1/3 and a couple of ounces of ash.
If you are looking for char for your gardern, you are better off using one of the retorts or system that are talked about here. TomC


I am with Al . The gasifier will produce different amounts of char depending how it is used .

On a 700 mile not stop trip using between 500-600 pounds of wood I will expect to get about 10 pounds of char and ash from the gasifier .

Driving around the farm I will get more char and ash per pound of wood .

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I was thinking of doing that too…but that would create much more tar…how would u deal with that…because u are basically a charcoal plant that just uses the energy…I watched people build a “Adam retort system” and that would work great but how does the whole tar deal work…it seems like u know ur stuff by looking at all the stuff on the forum


Hey wayne this is a great platform…I am ordering ur book tomorrow…I was wondering. …I see u use pretty big wood chunks…does it clog up at all or does it burn through it?

The tar is burnt off in the stove as it would in any other stove. If the stove is built beyond fire inside a box, you can condition the gases and crack the tar in process.

The charcoal will not have any tar, this fuel is refined and will run clean in a gasifier and will never ever foul an engine unlike direct wood gas.

I’d love to be updated on this…it sounds like a great idea…please keep us posted

Hello Michael .

If you are asking about a bridging in the fuel hopper it hardly ever happens .


Now I am wondering is there a reason mine don’t make as much char. Is it a good/ bad thing? Am I doing something wrong?

Maybe it has something to due with the position of your right foot. Sorry couldn’t resist :smiley:

How did you get to Larry’s place fly???

I am convinced it has a lot to do with that I do have a lead food and I like to down shift even with these automatics.
I flew out. He usually comes down to our place before argos and rides with us up there but that didn’t work out this year so i came up here to work with him.