UPDATE! Backpacking Gasifier Stove





Introduction: UPDATE! Backpacking Gasifier Stove

About: I'm not reinventing the wheel here, I am just trying to make stuff that actually works.

Hello, this is Quark- and I am here to show you how to make your own TLUD (Top Level Updraft gasifier stove), and you can look them up at http://www.build-a-gasifier.com/gasifier-wood-stov.... They are essentially a stove that burns the fuel not once, but twice. The base thermos holes allow air into the fuel, while the top holes allow preheated air down into the stove to basically burn the fires smoke. I recently learned about the design while looking up specification for the popular Biolite Campstove, a design which I sought to make. Only then did I learn that it was a gasifier, and the rest is history. They are often used in third world countries, due to the fact that they are incredibly cheap to manufacture and are 10x more efficient than just a plain fire. Because of the double-walled construction, it is easy to use a simple food thermos to make one of these beauties. Enough talking, Onward!

Step 1: What Does It Do?

A gasifier stove consists of two walls. The outer layer then has holes drilled along the bottom on the outside, while the inside has holes drilled in the bottom and the top. Air then flows into the bottom holes on the outside, and flow into the inner layer, into the fuel. Some air then rises between the walls, becoming heated and flowing out of the holes in the top of the inner layer, essentially becoming little jets of fire. For this project you will want a thermos, and various drill bits.

The thermos I used is: http://www.amazon.com/gp/product/B00408LQN8/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Step 2: Outer Layer

First, you need to drill the outer holes. Make sure you drill these outer holes above the indentation you see about 3/4 above the bottom, as this part of the thermos is separate from the rest of the unit. I drilled on small hole, around 1/2 inch above this dent, with maybe a 1/8 bit. Then I gradually went upwards until I used a 3/8 inch drill bit. Then I took a measuring tape and used it to evenly distribute the holes along a line parallel to the base, for a total of 12 holes. This is also nice because you will inevitably push through the outer layer a little hard, and end up denting the inner layer. Don't worry this is good. YAY!

Step 3: Inner Layer

Then take a 3/16 bit and drill into the dents created by the previous layers drilling. This will leave you a straight shot from the outside into the bottom of the thermos, and an easy ventilation route for air to get in. This is probably the easiest step, and is also the fastest.

Step 4: The HARDEST Part :(

The next part is to drill the inner top holes. I really hated this part as it took forever. I used a rotary tool burr to make a small dent in the rim, and followed these small holes up with a 3/16 inch drill bit. It was easy after the initial burring to make the dent and was straightforward after that, but I ruined several burrs in the process. You want to drill these above the protruding lip, but below the threads.

Step 5: Test

I tested the stove several times without anything on it. You can see from the pictures that it quickly developed hot coals in the bottom. I filled it with some wood scraps and paper towels, and after about 2 minutes, it stopped smoking and started gassing! This process usually takes at least 1 minute, but after that it is golden. The fire eventually starts to come out of just the inner holes, and looks really cool. I prefer to light the stove through the bottom holes, as it gives me a straight shot to the fuel.

Step 6: Pot Support

For the pots, I needed some form of support. This took me a while to figure out (with my dad's help) and it worked out very well. I ended up using some 1/8 inch thick, 1 inch wide aluminum bar. They pull apart in pieces, and stack into a cross that fits neatly unto the top of the stove.

Step 7: Finished

I have yet to finally boil water in it, but I assume it would take anywhere from 6-10 minutes to boil 1 liter of water. I plan on making a fan assisted box to help move the air in the bottom, and will update when ready. I would love suggestions on how the holes could be altered to provide better gasification, or how it can be made better.

Thanks for reading until the end of my first instructable, and I would love your vote in the Make: Energy Contest, and others. Thanks, Quark-

Step 8: Thermoelectric Fan Box Update

I just couldn't wait to post. No tests have been performed, nor has the sugru even dried. For the first update, I made a thermoelectric fan box to blow air into the box and create turbulence. This should hopefully generate more of a furnace type stove and cause more efficient gasification. It functions by using a peltier element to cause a temperature differential between the side facing the stove and that facing away. Aside from the fan, it has no moving parts.

You will need:

Thermoelectric module and compound: https://www.sparkfun.com/products/10080

and https://www.sparkfun.com/products/9599

Aluminum enclosure: https://www.sparkfun.com/products/11735

Squirrel cage blower: http://www.amazon.com/gp/product/B008P72QYS/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Schottky diode: https://www.sparkfun.com/products/10926

Sugru (or other method of ducting the fan): http://sugru.com

Step 9: Attaching the Fan and Copper Nipple

Firstly, drill 2 holes and position the blower in the manner mentioned above. Make sure not to attach it too well, as this is merely a testing stage. Next, drill the hole for the copper nipple, at the bottom of the box. I drilled this out with a 7/16" bit and tapped the hole, then gluing to keep it in place. For a matching hole for the nipple, make sure to drill one of the bottom 3/8" combustion holes all the way into the inside layer for additional screw space.

Step 10: Attaching Thermoelectric Module

First, drill 2 small, 1/8" holes in a spot so that the wires run directly from the module into the holes in the box. Then, run the wires into these holes and hold them at the other side. Now, attach the fan, red to red, black to black, with a Schottky diode on the red lead, white line facing towards the fan. Solder these in place, and make sure to run heat shrink over these leads before fully soldered, in order to prevent short circuits. Warm this tubing to shrink the tube over the leads, and, done! On the outside of the box, take some thermal compound and drop a little glob on the enclosure, squishing this over the cooler when you place it down. I also added little rolls of sugru around each edge of the module to keep it in place.

Step 11: Ducting Fan

Take one packet of surgu, and roll it around the copper tube in the bottom. Then, take the other packet and fold it into a small sheet, then smoothing them together and making an airtight seal.

Step 12: Adding Air Intake for Fan and Finishing Up

Simply drill a large 3/8" hole in the lid of the project enclosure in order to allow the fan to breathe and filter air. After this step, you are practically done! I would love feedback and ideas on grille shape and design, but this is what I went with. I included images of the nipple fitting into the hole I drilled in the canister, as well as it in the stored position.

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38 Discussions

Wow, no more having to buy those wasteful expensive gas canisters every time I go on a camping trip


1 year ago

You should consider adding a lm7805 12V/5V voltage regulator and an usb connector. With this setup you might be able to charge your Smartphone at your campfire (with a cable long enough!). ;)

If you need to, add a few capacitors, but make sure, that they can withstand the high temperatures!

Before connecting your electrical device ensure first, that the output voltage does not exceed the required 5V at the USB connector. Elsewise you might fry your device!

Great build! Would be awesome to hear how the fan worked out!


2 years ago


Would the sugru not melt due to heating? And it would be great if you posted somemore pics of the copper nipple attachment and such thanks! Overall great project cant wait to build

Increasing the top ventilation holes could also be done via your dremnel tool by cutting slots in between the holes. Also do this at the base where the fan blows in and also at the box holding the fan then use the surgu to make a square duct both inside and in between. That should boost the air volume. You may not want to drill through to the firebox at the fan output site or reduce the size of the holes...IMHO


3 years ago

I just want to thank everyone in the Instructables community for the amazing support and the win in the Burn it contest, as well as the finalist position in the Make Energy contest. Thanks everyone, I am sorry I haven't posted in a while I will have a 1000-2000 lumen bike light coming soon.

Congratulations on the first place finish and a great build!


Technically speaking, this is a pyrolyzing stove, not a gasifying stove. Gasification converts the carbon content of the biomass into CO and H2 gas. Pyrolysis merely heats the biomass until the combustible volatiles come off the fixed carbon. See this graphic I prepared while working at a biomass gasification equipment manufacturer: http://www.allpowerlabs.com/wp-content/uploads/201...

The smoke gets burnt to produce CO2 and H2O vapors at a very high temperature; these then get percolated through the red hot charcoal, which is highly reactive with oxygen at high temperatures. The carbon in the charcoal has such a high oxygen affinity that it yanks the oxygen off the CO2 and H2O to produce CO and H2 gases (carbon monoxide and hydrogen), both of which burn hot and clean. That's what gasification is. This stove only carries out pyrolysis.

The stove could be too long, with the bypass air going into turbulent flow and restricting total bypass flow. Just look at the smoke from a lit cigarette, and how the smoke goes from smooth flow to all curly. So.. Maybe use a shorter thermos, or build a ash trap into your design... And move the bypass air holes?

1 reply

The smoke from a cigarette goes curly when it cools to near ambient temperature and is no longer buoyant in the air.

Outstanding! What would you say is the total cost of this project? Also, have you had results from your testing yet? I am very interested to see if the fan helps much?

Great tutorial, upvoting it in the contests!

I would love to see it working. I want to know if the peltier built worked.

Very nice stove and Instructable! Your stove is a much more refined, finished product than most hiking stoves of this type.

Two questions: 1) How long does it burn or need more fuel sticks to be added? 2) Is there possibly a mod that could be made to side feed fuel sticks so you wouldn't have to remove your food from the flame for continuous heating?

1 reply

Hello, in reply to the mod idea for sideways feeding the fire. If you look up an rocketstove you can see that it's not that hard to add. Goodluck!

Great job!! Keeping the fuel off of the bottom of the burner might help some. I made a "wood gas stove" out of a large pork and beans can once that is very similar to your build. I cut a piece of 1/4 inch screen just larger than the inside diameter and wedged it in just above the bottom holes. This allowed for unobstructed air flow due to fuel blockage. I also added air via large blown up punching bag balloons and a small copper tube with the smallest hole a could drill in it. This was slipped into one of the lower holes and acted much like a pellet stove. My survival buddies were blown away by the whole set-up. It boiled water faster then a Jet Boil and only used miniature pine cones for fuel. Hope this helps and keep up the good work.

1 reply

3 years ago

You can put a fair amount of wood into it, as the original thermos held 2 1/2 cups of water. I need to test the length of the burn and the difference in cooking speed between the stove and the stove with thermoelectric fan.

I am wondering about usefulness.

For this size how much wood can you put into it?

How long will it burn?

How much does it cool down if you add more wood.

If you need to, say, cook pasta you need to boil the water then cook the pasta for 7-10 minutes. Would this do that without having to move the heavy pot to add more fuel?