Permaculture and Woodgas

I was wondering if there were any permaculturaly inclined folks in the DOW forum. I feel like wood gas powered vehicles fills a big hole in the permaculture way of life. Wood gas vehicles, unlike electric vehicles, are regenerative machines that produce biochar. This allows for the sequestration of carbon and opens up an avenue for increasing soil fertility, gaining yields (energy through combustion) through timber stand improvement/thinning/fuels reduction in forest fire mitigation. Very exciting!


I manage my family’s defunct tree farm. We still grow the trees but are too lazy to get the tax break from it :roll_eyes:. If I had any say we would be back in good status for it.

I also try to grow as much of my food as possible. I have a probably unhealthy distrust of store bought vegetables and fruits. I’m not far off from enjoying my own meats as well, would love to raise some chickens and maybe goats for weed/bramble management.


I would say having an unhealthy distrust of store bought vegetables is probably healthy lol sounds like you have a lot of great projects happening!


I like to keep myself busy. This year as a gift for my mother I bought a Pomegranate tree since she buys so many I thought I’d help pad her expenses out at least for the times it fruits.

My uncle lives on the same property and keeps bees. They will help a lot when I start an orchard hopefully this year. I would like at least two apple trees for feeding animals and making juice.


People have different definitions of permaculture, Kerem. I consider everything I do to be permaculture all based on maximum self sufficiency. Personal power generation. Food production, health care. Heat. I think anyone who makes the kind of commitment it takes to work at producing their own fuels is right at the top of the permaculture ladder. There are many folks here that explore other alternative fuels. I’m sure if you are looking for people who may share a particular interest of yours you will find some of them here.


I like the thinking of permaculture though it seems to have a lot more doctrine than appeals to me.

My quick thoughts… if you are making fuel, you don’t need to give a hoot about food safety. Permaculture takes a lot of its steer from avoiding synthetic fertilizer which is largely moot with fuel from a health perspective. If there is something foul in your human or animal life cycle that makes a tree grow faster… I would use it. Yeah - so grinder pump on that septic or animal runoff to help feed coppiced willow/etc for gasification.

If you have fruit trees with excess production, you can make ethanol with bruised and otherwise inedible fruit. Laws constrain that activity in the US but if you don’t sell a product and consume it locally… it’s unlikely to be an issue.

If you want food to eat? With all the love for this forum… you might not be in the right forum. Intensive agriculture has it’s own community. Basically you need to think about the availability of light, water, phosphorous, potassium, nitrogen from your sources vs requirements for what you want to produce and eat. There are ways of recycling those resources but the last three don’t fall from the sky and require care.

Azolla is a water cousin of the “Three Sisters” that fed indigenous cultures for centuries. It only needs the first two (light and water) to scavenge P and K . Azolla makes the Nitrogen it needs from air assuming it has enough light and water and the rest. Quite the miracle…

Likely Azolla is the source of most of our current oxygen to this day from an ancient arctic bloom that converted a C02 heavy atmosphere to present day ratios. It seems particularly undertaught given our current circumstance and by my read it’s sort of the cheat code for Permaculture. It’s exclusion makes me all the more skeptical about why it isn’t part of the convo.

These are private thoughts with academic backing but rarely pushed mainstream. Happy to hear I’m a loony but chiming in a little strong on a thing I think gets lean coverage. Composted Azolla is a weirdly ignored way of recycling waste streams.


I don’t think it is either/or.
You can actually use the woodgas in a generator and feed an electric vehicle.
Then you have a stationary power plant, then you don’t need to mod your vehicle and you may have a better way to incorporate it into the rest of your lifestyle. maybe charge two vehicles, or have backup power. Certainly, right now, modding a vehicle to run on woodgas is cheaper then an EV. However, if you can run your EV on electric generated from wood, then I don’t see any difference.

I just don’t consider it as one is better then the other. They both have pro’s and con’s.

If you really want to get into the carbon sequestering, then you probably want to look at making charcoal, and using the offgas, or distillates. You can make the charcoal, to run in the generator or use it as biochar.

There are several ways to approach it, it depends on how much time, work, and what your end goal is. You can incorporate it into a permie lifestyle. How you wish to go about that is up to you, there are several valid paths to travel.

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This is why (this is Azolla filiculoides or the North american species). From wikipedia:
In the areas of introduction, A. filiculoides is capable of rapid growth, especially in eutrophic ecosystems, and outcompete native aquatic plants. The dense mat of A. filiculoides causes lack of light penetration and an anaerobic environment due to detritus decomposition, causing a drastic reduction of water quality, aquatic biodiversity and ecosystem function.

In otherwords, it becomes invasive and kills off all the natural wildlife. The solution ends up worse then the problem…


Azolla only grows to excess when conditions are especially favorable and that is when the water body is chuck full of excess K and P (eutrophic as mentioned above). This state is typical of agricultural run off from synthetic fertilizer or animal waste. Azolla gets out of balance in a system that is already out of balance.

It needs to be harvested and composted (or just eaten by fish in an aquaculture system) to recycle those excess resources. In doing so the Azolla will leave the water closer to natural balance. Since it can scavenge P and K from water and fixes N from the air, Azolla can close the nutrient cycle for a small, otherwise resource starved area. That’s why I called it a cheat code.

Where it is deliberately cultivated, Azolla is typically grown in shallow, man made holding ponds, not natural water bodies. Eutrophic runoff is a typical water source to maximize production. That runoff is water that would otherwise foul natural water systems. The overflow from the cultivation ponds is left suitable for release into streams and natural ponds / etc.

Permies prefer self balancing systems of many parts so I get the reluctance to use Azolla. It is uniquely good at it’s job… so much so that it tends towards monoculture when that job is big. For me that’s a feature, not a bug. And with that said, happy to drop the topic.

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I was just saying, I don’t think there is any big conspiracy against it. Apparently they have used it in china and vietnam since like the Ming dynesty in rice paddies and it is actively promoted by the chinese government. It appears india is promoting it as well. In the US, one of the largest issues is nitrates in the groundwater which promote algae blooms among other things.

What I am trying to find out is they mention in some of the india promotions that the water has to be flushed out of growing because of the nitrogen contaminants. And it doesn’t grow during the cold, or hot season. It also has to be carefully stored. The chinese and dutch studies are saying there are fertilizer inputs like organic matter, and phosphorous. is it naturally leaching nitrogen back into the water?

One study I read mentioned something about heavy metals in the ash, when pyrolizing it into various byproducts. Does it consume heavy metals like some other marsh plants?

I really don’t know that much about it.


I know people that keep duckweed ponds which they harvest for animal feed. Super nutritious. It’s used as a crop like any other. Seem like I remember way back when Mother Earth News wasn’t geared toward the gentrified crowd that Amur and grass carp were used in many parts of the world to control aquatic plants, and didn’t present a problem as an invasive species, a status they have here, because those cultures considered them a premium food fish.


I am considering building a continuous biochar kiln for the wood chips/sawdust from local hardwood mills. Do you think that there is a market for fine biochar?

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There probably is. I would look on amazon to see if someone is selling it already. I would recommend innoculating it, with like compost tea. I think I saw someone selling it are part of compost, so they just mixed it in with their compost.

There is a market for wood chips and sawdust to make MDF.
But you might be interested in this. It is a machine a guy built to pelletize sawdust into chunks.

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Only issue with charring wood chips or sawdust is air doesn’t want to flow through it very easily. I have tried both in a TLUD form and using flame cap method.

TLUD wouldn’t even start and flame cap, it kept smothering the embers below and resisted catching fire.


Yes Cody your observation is correct. When a chunk of wood burns or a log. It burns from the outside in. Correct. As the chunk of wood burns to the inside it is being pyrolysis and gases are being released. These gases a passing through the already burning Charcoal. The Charcoal is not tiny little pieces of char. There is plenty of oxygen on the out side so it combustion is complete burning on the out side and ashs are forming.
Not with chips they burn up fast, this all takes less time. No big chunks of Charcoal, just tiny ones and lots of ash forming. Heat is not getting through the wood chips. The chips are like a insulation.
I think the best way is to put chips into a retort isolated from the fire, pyrolysis the chips to Charcoal with out the ashes.
When I am making Charcoal in a open pit I lose a lot of Charcoal if I do not shovel it out during the burn and place the coals in water. It is best to limit the oxygen when making good Charcoal the retort does this.


My two cents worth?

I work for Tree Service, which constantly having to pay dump fees, recycling our wood chips.

My boss told me, if I convert my Ford Ranger pickup to woodgas, he would give me free wood chips.

Any Tree Service that has to pay dump fees would be a good resource to approach, concerning availability of wood chips.

Many of the long-time customers asked us to dump piles of wood chips for their composting and garden projects. These wood chips contain lots of minerals and when mostly burned, make excellent biochar.

Some people make a very good soil out of the composted wood chips, biochar, blood meal, bone meal, wood ashes, and rock dust (available free from rock quarrys, that use bag house as part of crushing process) from different quarrys to remineralize soil mix. This process follows along square foot gardening method which has a lot of advantages.

Another use some people make with wood chips, is feeding chickens, who love to scratch and peck through insects & worms growing in wood chips compost heaps. I have a tiny Ford 8N tractor with front end loader attachment and backhoe attachment that work excellently for turning and managing wood chips compost heaps.

One final thought on the use of wood chips compost heaps: worms can be harvested and sold to fishermen; also utilized on homestead for feeding chickens, rabbits, and fish.

1 Pleasant side effect of tree service work is having access to an infinite variety of trees, from which to obtain starts.

Where are you want to go and watch you wish to achieve with wood chips is totally up to your imagination and how hard you choose to work in achieving your goals.


One of my thought projects right now is a simple retort for wood chips. Precisely because gases don’t flow easily in a bulk container full of chips, I was thinking retort style and spread the chips out over a wide surface to be heated indirectly.

The basic idea is create a sandwich of metal roofing material… corrugated or standing seam (but not anything galvanized!). The sandwich of roofing material defines two chambers… a combustion cavity on the bottom that generates heat and a top cavity holding the chips all spread out. Creating the two chambers requires three pieces of roof. Insulating the top and bottom would imply two more pieces of roof to protect and seal the insulation. What to use for the sides? Any old thing that will support the weight, doesn’t burn and is mostly airtight.

The wood chips get spread out over several square yards of flat metal in the chamber above and heated from below. Off gas from the charcoaling process would be ideal for driving the heat process to improve efficiency but that’s not critical. Direct fire with separate fuel is simpler and lets you perforate the roofing material to pass combustion gases directly through the chip bed for faster heat transfer. The off gas from the top chamber wouldn’t be fit for reburning if you went that route though. It would just be vented. If going with direct heat I’d keep a combustion chamber vent anyhow in case the chip bed creates too much pressure drop. A clever person could arrange for a very lightly weighted baffle on the combustion vent to encourage bed flow.

The roofing material should be self supporting so the insulation doesn’t need to be structural. I’d use any old cheap and easy insulation that is light weight: old rock wool scraps, perlite/etc. Slap one last piece of roofing material on top to weather proof and call it done. If the roofing material can’t handle the weight of the stack it’s easy to add supports. All thread with nuts/washers up through the sandwich would do the trick or just sheet metal on edge and parallel with the direction of gas flow, riveted to the roofing as appropriate.

Bonus upgrades/ideas… Have an airlocked pusher system on both ends of the charing chamber.
That way you can introduce chips in one side and push the char out out the other. Makes a batch process into a continuous one. Bonus/bonus, draw the combustion intake air past the char exhaust to pre-heat it for extra efficiency. Bonus/Bonus/Bonus, instead of insulating the top of the sandwich with rock wool / etc put your green chips on top to super dry them ahead of charcoaling. Bonus/Bonus/Bonus/Bonus charcoaled wood chips are likely to make a lot of fines. If not used for biochar… you could entrain fines in the intake air as a fuel source that would otherwise be tough to use.


Wood chips should be left to compost for a couple years before you grow root crops like potatoes and Turnips in soil heavily mulched with them. The crops pick up a unpleasant taste from them. After a couple years it’s fine.
The last few years since I’ve been playing with a lot of char I have been thinking of building some kind of furnace or heater fueled by injecting the powdered fines into some sort of cylinder like a fire tube. It would be a very hot fire if you could maintain the combustion. Would also only be practical if you had a huge supply of fuel to make the char out of such as wood chips. “I got a head full of ideas and their driving me insane” B Dylan.