Design choices for different fuels?

Hello everyone!
The last months I have seen some different gasifiers here that work for different fuels, but I don’t fully understand what makes them work with “x” fuel.

Joni seem to use a lot of green/raw wood and doesn’t use any pre heat or hot hopper/monorator hopper? at least in some of his builds?
Or like the chip gasifier he made which was a simple single nozzle design which was said to run on wood chips and sawdust.

So what makes one gasifier work with green wood and another doesn’t?
What makes one work with wood chips?
What makes one work with saw dust?
There was even some log gasifiers that was used in USSR that some user posted.

I have seen pics of a design (in joni-gas-generator-version-8.0 thread) that is said to work with any fuel, but it looks like it’s based on the imbert :thinking:

Maybe all these doesn’t make perfectly clean gas anyway?
But in a automotive application with a good condenser it doesn’t matter as tar have a boiling point of 300 Fahrenheit/Celsius.
So all tar and water will be condensed anyway?

Are a condensing or hot hopper best or maybe nothing at all?

Many questions, but I’m just a bit confused…

Jim Holmgren the reason is much more about Operational techniques (at least 75% of the solutions) in the same gasifier based on the different base fuels put in types.

This is why you cannot see the design differences.
The exact same one-button drip coffee maker for the Wife and I using exactly the same ground coffee produces dramatically different results. Ha! Why we sometimes race out of bed to be the ONE making! Each knowing, “Mine’s Better!”.
Ha! Ha! And hands down I do wood stoving much better than her in our same wood stove using exactly the same woods, split the same. MY 15 degree parallel sticks placing to make velocity inducing long slit passageways, devolving down to parallel hot charcoal beds. Versus her CampFireGirl/Boys Scouts full chriss-cross teepee non-heat supporting piece placements. Then just left with smoking sticks; after the initial flame out.

Gasifier operating search back the recently re-put back up Argo’s video of WayneK doing the first firing up to engine running of a fellows freshly built up Toyota gasifer system.
Watch and learn Operator decisions and methods from a Master.
Steve Unruh


And so’s not to single out just WayneK . . .
A few months ago J.O. put up an in-travel picture of his Mitsubishi pick up system temporarily stuck in place.
Open hopper smoking; burning-down, having to re-make a depleted out charcoal bed.
It WAS HIM the Operator knowing from his decreased performance (and gauges) that he’d expended, use-up his charbed. HIM the experienced Operator knowing without a charbed, you ain’t got nothing so far as a true wood gasifer.
Ha! And him the experienced wood gasfier Operator cursing himself for not bring along a bag of his own pre-made emergency wood charcoal.

And you mentioned Joni’s GJ 8.0 system. On that topic he put up a corrected direct link to his videoed series.
Watch those. Watch all of those over the course of 3-4 years.
What to see is HIM; as the operator.
He refuses to start and run his engine on his made gas until he is getting just the in-engine-compartment flare that he wants! Operator experienced. No tar babying up his OHC engine!

And it is these put up finds that to me are the real Gold on the DOW.
The REAL value of the DOW itself.


Now JimH here is my current take on why you are seeing different results from different people and designs.

Some are buying in to Four Zones operational theory. See Jim Masons excellent description in the Library section. Then designing and operating to keep these four zones made, and continually operating. Feeding one to the next.
Designing, operating for continuous, seamless hour, after hour, after hour.

Some buying into a Two Zone operational theory. Ahh. Basically one operational area from just below the nozzles and up to the hopper lid. And the second from just below the nozzles down through the restriction down thru the grate. These designing/operate in 4-8-12 hours operational cycles. Original factory Imberts with extended run hoppers.

And the newest “Design” theory of one-continuously evolving zone beginning at the put-in raw woody fuel to the grate finishing exit.
Joni’s; now BobMac. Now me, and others operating.
And this last working best with one, to two hours batch cycles. Left to evolve, use-up to down to just above the nozzles charcoal level. Then, Batch Re-fueling for then another one to two hours of good gas making cycle.
Or; shut down at this point, for a future operational cycle.


Some other observations, when doing gasification, it can be in a wood stove, fire pit, or wood gasifer. When most of the extra moisture is cooked out of the wood the whole process comes more efficient.
An example of this is at the end of a hopper load of wood when drive my truck, wood about foot above the nozzles I have notice repeatedly every time I have more shaft horses power to the wheels for like going up hills. How do I know my hopper level? By the temperature increase in my hopper.
I have noticed Just sitting around a open fire pit. More BTU’S coming at you and a noticeable change in how the fire, how it is interacting with wood, the smoke, moisture coming out of the wood.
In the wood stove this might mean changing the setting of air intake to get the same heat out of the stove.
Now what missing? The extra Moisture in the wood. When I go to refill my hopper when it is low on wood, smoke comes out of the hopper but less steam. If I stop to top off my hopper and it is still half full, just because of a convenient spot to pull over. When I open the hopper I notice more steam with the smoke comes out. Even the smoke has a different color to it.
This is why I really like the Idea of the vehicle vaccum exhaust pipe pulling a vaccum from the hopper pulling this extra not needed Moisture out of the hopper. Every little bit helps and yes we are still going to do it with the hopper moisture/tar condensation tubing on the side of the hopper for collection to the condensation tank. To me this a win win.
It stills goes back to using the driest wood possible. If you can sun dry the wood down to 5 % moisture in the wood that will be great. This is limited by where you live.


Yes, several reasons to that mistake.
No1: It was cold enough outside to affect the hopper temp reading. The alarm didn’t go off until it was too late.
No2: After 3 years and 15-16,000 miles, with no maintence on the hopper, buildup of tar and debrie has slowed down the condensation circulation - the hopper runs cooler (and collects less juice).
As soon as it warms up here, I will have to remove the funnel/inner wall and clean out or burn out the buildup.
No3: Distraction. Wife was eager to get going and I knew already when we left home that the distance we were going would require a refueling stop anyway - so - I didn’t bother fuel up 100%. Because of running out of fuel earlier than usual and listening to a lot of talking I forgot to pay attention to the hopper temp.
Wayne posted a funny video a while back where he handed the camera to Lisa and let her believe she was filming. He said he enjoyed just listening to the motor purring.
But there’s more to it. DOWing on my own I find myself constantly imagining what’s going on inside the gasifier. All my senses are used to be able to do that and mishaps can be avoided.
Not only is gasification a lonely business - you get the best results DOWing when you’re on your own and not distracted.


I’m glad to hear that your sweet wife still gets your attention :smile:


Very true JO. I usually screw up when showing the vehicle or giving someone a ride .


Yes JO, that is so true. I notice this everytime when DOW. Just before I need to refill my hopper up again on my gasifer, it will have better power than it’s normal usual operation. This can go for a few miles to 10 miles depending on the speed I am traveling at.
And yes in my mind I too try to imagine what is going on in gasifer. Many times times I have pulled over at the house and just opened the hopper up. After looking at the smoke clear, making sure of no buff backs, I note the steam coming out if any, moisture on the hopper lid, tar, and tar juice on the gutter plate and in the gutter and what it looks like in the hopper with the remaining wood, all of these little things can be important. All observations made, and taking note will make a person a better gasifer operator.
Hopper maintenance, cleaning the temperature probe to assure correct hopper temperatures, and all the other maintenance to the rest of the gasifer is very important to it’s success and less troubles going down the road. Most of my problems have been related to not doing this. Yes I am still learning maintenance, maintenance do not over look it. This is why we call ourselves gasifer operators and not drivers. You drive a vehicle and you still have maintenance that needs to be done, but you operate a gasifer in the vehicle driving down the road. We should always consider ourselves operator/ drivers. In generation of electricity you are a operator of both.
This is so important for gasification. For the operator to be in tuned and knowing what is going on. Wisdom, knowledge, understanding, success.


I agree 100% with that last BobMac.

The shame is the real route that works is:
1st a bit of success.
And that leads to understanding as #2.
With only then, the ability to apply read knowledges.
Wisdom?? That is finally accepting to re-order these in a sequence that actually works.

Sigh. Any other sequence than → a bit of success → a bit of understanding → THEN applying read knowledges → to arrive at wisdom . . . always seem to stall out at one of the steps.
Repeating, and recycling. Stuck. Over, and over, over again.