Introduction: Power in the Apocalypse (How to Build a Wood-Gasifier)

In this Instructable I will be showing you the steps I used to build my Wood/Biomass Gasifier. It was really a fun project and I would encourage anyone serious about preparedness to build one. Now in case you don't know what a Gasifier is (and don't feel bad if you don't as very few people do lol), they are quite simple, let me explain. Essentially all gasification is, is a form of incomplete combustion, heat from the burning solid fuel creates gases which are unable to burn completely because of the insufficient amounts of oxygen from the available supply of air, it then filters those gasses(which is by weight: 20% hydrogen, 20% carbon monoxide, 50 to 60% nitrogen, and a little bit of methane) And you can really use any kind of Biomass(organic material) that will burn. You can even use things like paper, coal, peat, and lignite. You can then use that filtered gas to run any thing from a generator to a car. So now that you have a basic understanding of what gasification is, lets get down to the build!!!

Step 1: Basic Information.

Don't worry, for this project you wont need any fancy tools or equipment. Just a welder, an angle grinder, an oxy-acetylene torch, and a drill, along with the knowledge of how to use them. Most of the materials used were found in friends' scrap piles so for me cost wasn't a big issue. And you can (in theory) make this to whatever size you need, so keep that in mind when gathering materials. But don't forget, whatever fuel you use has to be able to feed through the fire tube easily. The fire tube acts as a sort of dryer and hopper. The fire tube feeds the fuel into the shaker grate, which is where the fuel combusts. The gasses are then sucked out of the gasifier unit and pulled through the filter units. And after doing some research I chose to go with a cyclone filter and a media filter. Ideally I should have added a condenser after the cyclone filter to to get as much moisture out of the gas as possible. But oh well lol. But I would recommend adding one if you plan on building one of these.

The size of the fire tube governs the size of the engine you can run. Here is a chart showing the fire tube sizes and the respective horsepower. The larger the fire tube, the more fuel it will burn, the more gas it will produce.

Inside diameter (inches) Minimum length (inches) Engine power (hp)

2 16 5

4 16 15

6 16 30

7 18 40

8 20 50

9 22 65

10 24 80

11 26 100

12 28 120

13 30 140

14 32 160

Step 2: Building the Gasifier Unit.

The first thing you need (as with anything) is a solid foundation. Because I was dealing with scrap metal, the frame is made from 1"x2" tubing and angle iron. I used a piece of 4.75" exhaust pipe for the fire tube, and the shaker grate is made from a brake rotor with the bottom cut out, and .25" rebar welded in place. The grate is suspended from chains welded to the fire tube supports. I left about 1" from the bottom of the fire tube to the bottom of the grate. I used 1.25" pipe for the ignition tube, which is that pipe leading into the side of the fire tube.

Everything on a gasifier needs to be air tight, which presented me with one of the main problems. How to get the shaker grate assembly through the side of the barrel and make it rotate while keeping it air tight, and it had to be heat resistant. My solution, was to run the handle rod through a piece of .75" pipe capped off on both ends, and then pack that with fine steel wool. And that seems to have done the job quite well. The purpose of the shaking action is to sift the ash and dead charcoal through the grate to make space for more fuel.

The ash clean out port is made from a piece of 6" pipe with a cover made from a .25" steel plate. I welded some lengths of 3/8" all thread to the sides of the 6" pipe and drilled corresponding holes in ears I left on the cover plate. And I sealed it with wood stove gasket maker and cemented it in place with stove cement. Then you just bolt and unbolt the cover plate as needed.

The pipe you see going into the side of the fire tube is the ignition tube. Its capped off with 1.25" coupler with a washer welded on to seal it off, and I decided to add a handle to make it easier to use.

Step 3: The Cyclone Filter.

Okay good, the hard part is over with lol. The filter units are the easiest part of the whole build. The first of the two filters is a cyclone filter which acts partly as a filter (obviously) and partly as a condenser. The water vapor, creosote, tar, and some particulates are collected on the inner sides of the filter as the cyclone of gas spins. These then run down into the collection jar. I chose to use a 5 gallon propane tank as the filter housing. All I had to do was run a pipe from the gasifier unit in through the side of the tank at an angle, to initiate a cyclone. Then run another pipe through the top of the tank which sits about 2" from the bottom. I flipped the tank over and used the original top of the tank as the bottom of the filter. The threads from the valve hole accept a .75" pipe nipple, which is attached to a flange and bolted to a jar lid. I added a rubber gasket between the flange and the lid to make a nice air tight seal. Now just screw on the jar and tadaa, a catchment basin lol. And that's really all there is to the cyclone filter.

Now. . . onto the next step.

Step 4: The Media Filter.

The media filter is made from a metal strong box tipped onto its side. The pipe leading through the top of the box comes straight from the top of the cyclone filter. And then you would just fill the box with an appropriate filter media such as wood shavings, cloth, or even as a more expensive but safer alternative, steel wool.

Next comes the plumbing. You can see the logic behind the pipe assortment there, but i'll explain anyway. So first there is a tee which splits between the air pump and the outlet to the engine. The valves are for switching between the two as well as acting as a choke for the air pump. And the pump leads up to the flare. The purpose of the flare is to check gas quality before routing it to the engine.

I figured that in the apocalypse the chance of having a working wall outlet is pretty slim lol. So I chose to use an air pump that could run off of a 12v car battery. Nothing special, just an air mattress pump that connects to a vehicles power point.

Step 5: Tips on Using Your New Gasifier.

If you decided to reproduce this project, here are some tips and tricks to get you started. Firstly, the fuel you use must be bone dry, and I mean REALLY dry. Store bought wood pellets seam to do the trick nicely.

So you built a gasifier and want to try it out... Now what? First fill the fire tube with your fuel of choice, then simply turn the pump on(with lots of choke at first), then uncap the ignition tube, insert a source of ignition, let the fire catch, recap the ignition tube, and as the fire progresses let off the choke a little bit at a time. After it has been running for awhile hold a flame to the end of the flare and, with any luck, the gas will ignite. Between the gasifier and the engine, the gas will need to be pre-carbureted, which is as simple as adding a tee in the hose to bleed off excess gas. Then you just run the line into the engine carburetor and that's it! Unfortunately, I haven't tested this on a full size vehicle yet, as I am only 15, and my mom wont let me get anywhere near her car lol.

Step 6: In Closing.

Lastly I added a handle and some caster wheels, as well as sealing everything with wood stove sealer and giving it a coat or two of high heat paint. This was a fun and very educational project, I would really encourage anyone who is interested in being prepared, or just looking for a fun project, to build a gasifier. If you enjoyed this instructable, let me know in the comment section below. If you have any questions please let me know and I will do my best to answer them.

This is not something you should use indoors. As it does produce flammable and toxic gasses.


As the reader, you assume all risks of reproduction of this project. I am in no way responsible for any damages or injuries to anyone or anything during the making or using of this project.

If you really enjoyed, please consider voting for me in the Apocalypse Ready contest. :)


Malkaris (author)2016-11-07

very nice build, I've read there is a way to convert Syngas I to diesel, but I'm not sure how that exactly works.

tatebullrider (author)Malkaris2016-11-07

Yeah, I am currently working on a machine to turn coal into diesel. It's essentially the same process, only using indirect heating via a burner. The gasses produced are then condensed and ran thru a fuel scrubber.

Thank you so much for the comment!

Malkaris (author)tatebullrider2016-11-10

do you know the process for converting syngas to diesel? could you point me at something to learn? I've been looking at a way to use plasma to turn material into syngas too.

Flenters (author)Malkaris2017-07-03

Above is a link to a forum where a lot of people has done a lot of work regarding the plastic to fuel process.

tatebullrider (author)Malkaris2016-11-14

This guy can explain it better than I can lol. . He also has alot of other alternative energy projects you might enjoy. Hope this helps.

JakeY16 (author)2017-05-07

Are you on FB or IG? I'd love to follow you!

tatebullrider (author)JakeY162017-05-08

Unfortunately, I don't have any social media accounts. However I do have a Youtube channel. I only have one video right now, but I have plans for many more! I'll post a link soon.

JakeY16 (author)2017-05-07

15??? Dude, that's awesome! This article is the best I've seen on Gasification! Keep it up buddy!

tatebullrider (author)JakeY162017-05-08

Haha, thank you so much!! I'm really glad you enjoyed it. I will :D.

pfred2 (author)2016-11-06

I've heard of gassifiers. They were popular in World War Two in Germany.

tatebullrider (author)pfred22016-11-07

Found this pic.

Wood gas car3.jpg
pfred2 (author)tatebullrider2016-11-10

Yes when you look at Google images of gassifiers the first couple rows are all WW2 German in origin.

ThomasK19 (author)pfred22016-11-30

Some are still/again in use esp. in rural areas in Russia and Scandinavia for cars. But here in Germany you can actually buy those for heating your house. The following link is in German and I'm not affiliated with them, but bottom right you find a schematic of what the OP has build on its own. These gasifiers come at a price of ca. 5k € (or $).

tatebullrider (author)pfred22016-11-07

That is correct. They were popular all over Europe at the time, due to the fuel shortages. I was debating whether or not to add a little history, but the instrutable was already quite long.

paul29690 (author)2016-11-26

Hi tatebullrider, thank you for an excellent instructable. I think you
should be commended for your acquired knowledge and passion for an
alternative lifestyle. Your parents should be commended equally for
having the sense to keep you away from the 'sheople factory'. Stick with
your passion, your gut and your insatiable appetite for knowledge and
how that can be converted into making things. You are a survivor, a
warrior and a valuable asset to any community.

tatebullrider (author)paul296902016-11-26

Wow... you have no idea how good that makes me feel :). Thank you so much for the kind words!!!

offseidjr (author)2016-11-21


tatebullrider (author)offseidjr2016-11-21

Thank you, i'm glad you enjoyed it. :)

Razanur (author)2016-11-08

Awesome build!

I've been toying with the idea of building a gasifier for a long
time (but you know, time - the one thing ppl over 18 always claim to
have less of than anyone else). But my idea was more in
the direction of plastic gasification for third world countries. Right
now, plastic (together with everything else) usually gets burned in smouldering
open fires on the streets. I would love to be able to burn it in a hot
and more or less clean fashion and get energy out of it. Especially
since a lot of cars run on gas anyway (e.g. in Pakistan or Iran), or
people cook with it (though with 20% CO you might not want to use it for
cooking ;))

So what do you think? Could you use this gasifier with plastic? Or a mixture of plastic and wood?

tatebullrider (author)Razanur2016-11-08

You can absolutely make fuel from plastic, via indirect heating. And it's way simpler than one might think. Essentially all it is, is a sealed metal container filled with plastic, paper, wood, coal or really any suitable substance. Heat that container over a fire, and run the resulting gasses through a series of condensers and collection containers. I would probably have a series of at least 3 condensers with a collection container between every one. What you will be left with is whats called "biocrude." The biocrude is then refined via the same process. (indirect heating and condensing). The results are a crude form of gasoline.

If you build one of these please let me know. It's great to see people like you, out there making the world a better place. Thanks so much for the comment!! :)

ed-romes (author)tatebullrider2016-11-10

On. This comment you say over a fire have you ever concidered using the sun ?? Any light reflecting item such as a parabolic dish or a freisenell lens like those found in old time image projectors that are really the same as a magnifying glass with rings !! Some can get one spot hot enough to melt lead or solider !!! Or star a fire :-D

tatebullrider (author)ed-romes2016-11-10

This is a good idea, but unfortunately I don't think you could get even enough heat distribution. In order for pyrolysis to occur, the fuel has to reach 451 degrees fahrenheit while in the sealed metal container. I am absolutely not saying that this is not possible though, just a bit harder to achieve than lighting a fire. Thank you for the comment, and keep on coming up with good ideas. :)

ed-romes (author)tatebullrider2016-11-10

With correct size and angle you can get up to 1000 degrees or more lead has a higher melting point than 450

tatebullrider (author)ed-romes2016-11-10

Like I said my only concern would be even heat distribution, but if you could figure that out it would probably work. If you try this please let me know I want to see how you did it. :)

aebe (author)2016-11-09

Very nice build . I helped put one together ('78) that went on a '53 Studebaker with a little flathead six . Owner loaded it up and headed off towards Missouri .

tatebullrider (author)aebe2016-11-10

Wow, that sounds cool. Thanks for the comment.

Edgar (author)2016-11-10

Great Instructable, went a link to my Blog, and this can also improve some impoverished folk's lives, this Winter, as the base for a Oven and Water Heating project... Here's the Blog:

Straw_Cat (author)2016-11-09

How much biochar does this produce?

tatebullrider (author)Straw_Cat2016-11-09

There seems to be very little of any bi-product (ash,char, tar,etc...)being produced so far. But I really haven't been running this to often so... as of now not much lol.

boatmakertoo (author)2016-11-09

Tatebullrilder, Congratulations this is clearly a very evolved device: After WWII gasifiers were used in Europe and Britain to power motor vehicles including tractors. In some cases the gas was collected in large bags and strapped on the back of the operator of a powered cultivator or even a motor bicycle. Those were desperate times there and not unlike an apocalypse. Fuel and food were scarce as was everything else. Along with the charred wood and the tar produced is a small amount of methyl alcohol which is a useful fuel. If you add a condenser you might be able to collect this as well. (Don't drink it. It's poison.) The ash is a source of sodium hydroxide and potassium hydroxide, good for apocalyptic soap making and dissolving zombies.- Boatmakertoo


I entered this in our local county fair and included a presentation board, and I had to do alot of research for it(obviously) and I came across lots of cool stuff like that. I don't know why this technology isn't more used. I have plans for another build soon, a sort of "refinery." Turning household garbage into gasoline. I'll probably show an instructable on that when it's finished.

wheeets (author)tatebullrider2016-11-09

Please do

tatebullrider (author)wheeets2016-11-09

I'll do my best!!

ron.walker.1690 (author)2016-11-09

Hi Tatebullrider, I enjoyed your instructable. I have a few comments. It is important to get the tar and other condensate stuff out of the gas stream before it gets to the filter. So cooling the gas does that and if it is a separate section, it can be cleaned out by just a pull through(?) The tar & stuff could clog an engines innards, not to mention any dust in the gas. Your filter looks like it would get the dust OK. keep up the good work. If you wanted to burn larger pieces of wood it might be necessary to have a tapered fire tube so that nothing could be caught in a corner. I made a similar burner for heating out of bricks and the pieces of wood all slid down to the hot zone readily. However I had problems with controlling the rate of burn, but the engine would control that.

Ron W


Thank you for the comments, I am absolutely no expert, so any words of advice are greatly appreciated. Yeah this was more of a learning project. Its far from perfect, but I plan on taking what I learned in the building of this one, and building a second one. And actually I am left with quite a bit of liquid in the collection jar when I am finished using it, do to the cooler walls of the cyclone filter.

M. DwayneS (author)2016-11-08

Entertaining 'ible! Well done. Seems to me there are always several wood-gasifier vehicles in the Mad Max movies with the dearth of oil/gas after the apocalypse. Guess, you'll be ready. Just be one of the good guys, ok.

tatebullrider (author)M. DwayneS2016-11-09

Maybe I will... Maybe I :)

nealalan (author)2016-11-08

Enjoyed reading your instructable!!! You should check out a post-apocalyptic reality show the Discovery Channel aired in 2009, called "The Colony". They build a couple wood gasification systems and I believe hooked it to a small motor attached to car alternator.

They also built a number of other awesome projects that really inspire any maker!

Not sure if there is a place online to watch it all, but I'm sure you can find some photos and Wikipedia has a lot of details on it.

BTW, where are you located? (What state?)

tatebullrider (author)nealalan2016-11-08

Yeah I watched both seasons of "The Colony" and really enjoyed it. And yes I remember the generator they made, I believe it was a pressure washer engine hooked up to a car alternator. That's actually where I first heard of a gasifier lol. I am located in Oregon btw. I am assuming you're asking because of the background in the pictures? And thanks for the comment.

jaxboy (author)tatebullrider2016-11-08

On the History channel, the series "Mountain Men", Eustace in the mountains of North Carolina ran his truck with a gasifier, and it enabled him to drive up some fairly steep hills carrying a medium-sized load. He used the truck to go back and forth to town when he had to purchase things. He had a saw mill, and used sawdust as his fuel, if I remember correctly.

achollowell (author)jaxboy2016-11-08

i remember that also in one show they were going up in the mountains and ran out of fuel got out walked to edge of road and cut more wood to fuel truck

JerryS42 (author)jaxboy2016-11-08

There were tens of thousands of wood-gas powered cars in Sweden during WW2. Performance-wise, wood is a quite attractive alternative to petrol i cars, if the practicalities can be solved.

tatebullrider (author)jaxboy2016-11-08

Hmm.. I don't think I have seen that episode yet. I'll have to look that up. Thanks.

MakerMichaelB (author)2016-11-08

Awesome build! I really like the simplicity of this setup. Couple questions:
* Could you post a pic with the flare tube on fire to show a rough example of how much gas it produces?
* How do you get it going with the pellets? It looks like they'd fit through the grate & not leave room for combusting.
* Do you use any type of hopper or does the fire tube give you a pretty good burn time? Do you have a rough idea how long it'll burn using what type of fuel(s)?
* How do you empty out the ash?
I'm looking into building an enclosed unit for heating up my shop this winter & your build has me all fired up to get started. :-) If you're thinking of powering a vehicle or enjoy random alternative energy stuff you'd enjoy the videos posted by MrTeslonian on YouTube. He has a small pickup run by gasifier that also collects different grades of biofuel. He has multiple condensers set up like grates above the sides of the truck bed. Pretty slick setup. Here's a link to his page: There's a couple hours worth of amazing Maker activities on there.

Gordyh (author)MakerMichaelB2016-11-08

"How do you get it going with the pellets?" Most people start with a layer of charcoal on the grate then add the pellets or wood, then shut the system down before everything in the burn tube burns to ash so you have the charcoal already there.

For heating a shop you'd be better off building a batch box rocket heater, look on Youtube. It will be a lot less complicated to build and very much more trouble free ;-)


Hey there, thanks for the comment.

Question 1: About the flare tube, the amount of gas produced is dependent on the suction. the suction pulls air through fire tube which fuels the combustion. So in a way, the suction of the engine only makes enough fuel for itself to run.

Question 2: So far I haven't had any problems with the pellets falling through. You just have to space the rebar grate right.

Question 3: I have never run a full fire tube through so I really don't know, sorry.

Question 4: There is an ash clean out port located on the bottom of the barrel.

I hope that this helps, please let me know if you have anymore questions.

And yes MrTeslonian is one of my favorite Youtube channels lol.:)

IanC15 (author)2016-11-08

Episodes of "The Colony" available on Youtube
(Keyword search) "Discovery channel the colony"

Quite Composed (author)2016-11-08

Excellent project and instructions! I have enjoyed reading about your project and the photos of your build.

The last time I visited Lane Motor Museum in The Nashville area, they had a vehicle from the 1940's that have a coal conversion (gasifier). In the 1970's the magazine "Mother Earth News" carried a couple of interesting articles on a gasifier that the builder used to power his small pickup. He would start burning the wood, then start his pickup with gasoline and once enough wood had been burned and collected into a collection tank he would switch to the fuel from the wood sending it to the warm motor through a dual source carburetor (originally designed for gasoline and propane (I believe he may have changed the size of the propane orifice)). Eventually, he added a trailer to allow him to carry extra fuel (wood).

May I suggest a few things to consider for your next build? (Please understand that the following thoughts/suggestions are NOT a critique on your work, just some things to think about.)
My first "suggestion" is one that you have already mentioned, i.e. the addition of a condenser after the cyclone and I am only urging you to follow through with your idea.
The second suggestion, (an important safety suggestion) is the elimination of any and all steel wool. Steel wool and flammable gases are never a good combination, especially when heat and oxygen are involved. Without going into detail, I know of several instances in manufacturing facilities where the use of steel wool ignited flammable gasses causing damage in the facilities. For the shaker area, I would consider packing material as used in valves that service flammable gases, and I would use a different media than wood shavings or steel wool. Perhaps some small gravel or chat might be worth considering after cleaning it to ensure that you are not passing any contaminants to the motor. You can watch heated steel wool on the Internet by Googling "9 volt batter and steel wool."

One last thought...
When looking for a motor to use with your generator (if concerned about an apocalypse), you should attempt to locate an older motor that uses points as it is less likely to be damaged if there were an emf pulse in your area. Typical electronics are expected to be damaged.

Have you considered looking at Stirling engines to generate electricity? Although Stirling engines have a few negatives (for instance, they do not create a lot of torque and they are an EXTERNAL combustion engine), but they will reach a good rpm using any external heat source that you decide to provide (wood, solar, animal dung and many other fuel sources.). Depending upon the build (using excellent bearings and a heavy flywheel), a Stirling engine is capable of QUIETLY working for a little while after its heat source has been removed.

Just some ideas which you may have already considered, but thought I would mention in case you had not yet considered them.

Thank you for posting your project for all to see. Again, your build was fun to see and read. Please let us know if you make a video showing your gasifier running a motor as I (and I'm certain others) would love to see more of your project.


Thank you for the comment. And I appreciate any and all ideas to improve this design, so thanks again. And I did know about the whole steel wool thing. I am planning on possibly using rock wool. The generator I have is a homemade one, between 15 to 20 years old, so I am not concerned about hurting it lol.

Gordyh (author)tatebullrider2016-11-08

On the steel wool issue. I saw one guy build the pipe and rod thing like you did, But he lightly greased the rod and filled the pipe with high temp RTV silicone. The grease kept the silicone from sticking to the rod and gave a nice tight fit.