MAKE: PROJECTS

Wood Gas Camp StoveMake a simple tin-can stove that costs 99 cents, runs for free, and

sequesters carbon as you cook.

By William Abernathy Difficulty: Easy Difficulty: Moderate

Nearly half the world’s population cooks and heats using solid fuel, much of it burning up

in pits that have seen no improvement since Homo erectus first tamed fire.

This is not a small problem: inefficient cooking fires waste fuel, impoverishing both the

480 395 366 3

planet and the person burning it; they inject startling quantities of soot, carbon dioxide,

and worse greenhouse gases into the atmosphere; and they injure and kill the families

who use them to cook and stay warm.

You can build a simple example of an appropriate technology that addresses all these

problems: a biomass gasifier camp stove. It sounds more complicated than it is. Charring

wood or other natural solid fuels releases gases that burn quite nicely. If you’ve ever

watched a campfire closely, you’ve seen little jets of smoke erupt from the wood ahead of

the flame. If conditions are perfect, a smoke jet catches fire and turns, briefly, into a tiny

geyser of flame. A good gasification stove recreates these conditions reliably, generating

smoke and moving air to produce these little fire geysers on demand.

There are many designs for efficient camp stoves, and gasification is only one way to

boost the efficiency of a cooking fire. The wood gas stove in this article is an elegantly

simple gasifier design called a TLUD stove (for top-lit updraft), also known as an inverted

downdraft stove. If you don’t care how it looks, you can build it with a can opener, a

punch, and a big rock. This design, which I’ve adapted from one I first saw on

Instructables, is built around a 1-quart paint can. It easily boils enough water for a small pot

of tea or a bowl of noodles, using nothing more than a fist-sized charge of scrap wood.

HOW IT WORKS

This TLUD camp stove works in batches: fill it up with twigs and woody bits, and light it

from the top. As the fire burns, it makes a layer of hot coals, and as this burning mass

descends into the can, it becomes starved for air. Enough oxygen comes up from below

to keep the embers alight, but not enough to sustain a flame.

This charring layer slowly descends, releasing flammable gases as it goes — a process

called pyrolysis. The hot gases rise to the top of the camp stove, where they are met by

an inrush of preheated air and, if all goes well, combine completely with this air in a clean

secondary burn that consumes the methane, soot, and carbon monoxide produced by the

primary combustion.

When a TLUD is dialed in, it’s lovely: a layer of smoke hangs over the coal bed like a fog,

and appears imprisoned by a gauntlet of inward-facing flame jets that rush in from the

edges of the stove. While the stove is gasifying, it’s remarkably clean: there’s little or no

smoke and only a faint odor, reminiscent of diesel or creosote. It leaves a trace of soot on

your pot, compared to the heavy blackening an open fire imparts. And when your camp

stove is done gasifying and the flame jets go out, clean charcoal remains in the stove.

This residual charcoal is a fringe benefit: not only can you use it for gunpowder (see

MAKE Volume 13, page 54), but you can cook with it a second time in a clean-burning

charcoal fire. You can also throw it into your compost and bury it. Called biochar, this

buried charcoal enriches the soil and actually makes your carbon-neutral biomass fuel

carbon-negative.

PARTS

Food can, 19oz, steel Commonly used for baked beans, chili, and pineapple chunks, thesecans snap neatly into the top of the quart paint can. The critical dimension, the lip of the can,must be very close to 3-3/8". Do not remove the bottom.

Chicken or tuna can, 12oz, steel to make a standoff that keeps the pot from smothering theflame

Chicken or tuna can, 12oz, steel to make a standoff that keeps the pot from smothering theflame

Scrap wood, 1-1/2"×1-1/2"×7" (or longer) for a backup block, to keep the cans from dentingunder the drill, or spinning and hurting you if the drill bit grabs.

TOOLS

Saw (table or hand), or router

Computer, printer, and drilling templates download from makeprojects.com/v/27

Caliper, ruler, or tape measure if you’re not using the drilling templates. Electronic, dial, orVernier calipers will work.

Machinist’s dividers with layout dye or a Sharpie marker; and woodworker’s marking gauge ormachinist’s surface gauge if you’re not using the templates

Prick punch

Hammer

Electric drill

Step bit, 1/2" It’s safer and cuts a cleaner hole than twist bits, which grab and tear sheet metal.

Can opener

Tinsnips

C-clamp

Half-round file

Vise

Eye protectionSTEPS

WARNINGS!This camp stove produces and consumes carbon monoxide, a deadly poison. DO NOT

EXPERIMENT WITH THIS STOVE INDOORS! Use it only outdoors.

Your stove will get hot. Using it on a wooden bench will leave a scorch mark. Use it on concrete,

a tile you don’t care for (thermal shock may crack it), or on dirt you don’t mind scorching.

PROJECT STEPS1. Prepare the backup block.

2. Mark the 1qt paint can.

ADVERTISEMENT

Step #11: Add the standoff, and get your ramen on!

3. Punch 12 o'clock mark.

4. Divide, scribe, and punch bottom of can.

5. Drill the 1qt paint can.

6. Mark and drill the 19oz food can.

7. Drill the bottom and snap cans together.

8. Mark and drill the standoff.

9. Enlarge the hole and smooth edges.

10. Start the Wood Gas Stove

11. Add the standoff, and get your ramen on!

As the fire burns down past the side jets, blow down on the coals to start pyrolysis. Try to get a

uniform coal bed all the way around the can. Once you see good coals with fire floating on top, put

the standoff on the stove, rim up.

If you see an orderly column of flame rising with no smoke, you’re gasifying! Put a pot of water on top

and get your ramen on.

When the fire goes out, you’re done with this charge. You can pile another charge on top, but you

may need to relight it. To save the charcoal for reuse or sequestration, pour in some water. To reduce

it to ash, leave it for another half hour and it’ll burn away. When you’re done, the standoff nests neatly

between the other 2 cans for easy storage.

You can experiment with changing the intensity and duration of the flame by changing the size of the

hole on the top of the stove. The standoff lets you choose between a 2-1/2" hole or a wide-open top

simply by flipping it over. You can add old can lids with different-sized holes cut in the middle to

“throttle” the flame higher or lower.

WILLIAM ABERNATHY

20 Comments MAKE Login1

Share⤤ Sort by Best

Join the discussion…

• Reply •

Richard Holmes • 2 years ago

Wait, what? You're cutting a 3" deep slot into a 1 1/2" x 1 1/2" piece of wood?

15△ ▽

• Reply •

ccouden • 2 years ago> Richard Holmes

Measurements are updated. Sorry for the confusion!

△ ▽

• Reply •

wabernat • 2 years ago

Richard: I do not know where these errors came from, but I suspect there was an issue with the

fractional characters. The slot in question is 3/8" wide by 5/8" deep.

I will bring this to the attention of management...

Good catch. Thanks.

--William

2△ ▽

• Reply •

Fergus Gallagher • 2 years ago> wabernat

That 32" wide food can is a bit surprising too!

2△ ▽

• Reply •

Alex • 2 years ago

Well, with a Led lampen you can make some kind of stuff similar

1△ ▽

Johnny Gnash • 2 years ago

Is this a variation on a rocket stove? This stove certainly looks nice and looks to be compact and

lightweight.

Recommend 1

Share ›

Share ›

Share ›

Share ›

Share ›

• Reply •

lightweight.

1△ ▽

• Reply •

wabernat • 2 years ago> Johnny Gnash

Rocket stoves burn the fuel directly and maintain a high temperature to ensure complete,

efficient combustion. This design works by charring the fuel and igniting the smoke. Both

designs have their pros and cons.

With no insulation, this TLUD definitely wins on weight!

△ ▽

• Reply •

Jim Wayman • a month ago

see more

Excellent stove and plans, thanks! My first test boiled 2 cups of water in a stainless steel GSI cup

no lid in just over 10 mins.... second test using the same pencil size wood about 1" long boiled 2

cups of water in 5 mins! I used Optimus Terra cup with the fins on the bottom and used the smaller

pan for a lid. I boiled 2 more cups of water still using the first load of wood fuel (filling the can and

starting a fire on top of the wood). The stove fits perfect in the Optimus cup set.

I did drill more on the bottom side if the inter can.

△ ▽

ukdiveboy • a year ago

I used this design as a template, but as I was too lazy (cheap?) to go buy a paint can I scaled back

and used to regular household beans cans.

- http://www.webooma.com/hobo/

@Ruaridh If you want to try this in England, the smaller of the "tins" I used was a Heinz Baked

Beans tin (16oz). The larger is 22oz.

Works great. It am amazed at how much water you can heat with very little wood. A great efficiency

boost over an open fire.

Share ›

Share ›

Share ›

• Reply •

see more

△ ▽

• Reply •

Derek Tombrello • a year ago

I am just curious... where did you find cans of these sizes? My local hardware store doesn't sell

empty quart cans, and the food cans in my local grocery stores (as well as my well stocked pantry)

are only 15 ounces (for the chili, beans, etc cans) and 5 ounces (for the tuna).

△ ▽

• Reply •

AlphaGenesis • a year ago> Derek Tombrello

to get the can to build the stove go to a paint store and tell them you would like to buy a new

unused quart paint can. hop this helped...

△ ▽

• Reply •

Ruaridh • 2 years ago

Does anyone know the equivalent UK sizes for paint tins and food cans, or would someone be able

to give me the dimensions of them separately, I just don't want to approximate it and find it doesn't

fit.

Thanks

△ ▽

• Reply •

paul beard • 2 years ago> Ruaridh

I would guess the same physical sized cans/tins exist, just with different volumes. The

crucial dimension is 3-3/8".

△ ▽

• Reply •

Ruaridh • 2 years ago> paul beard

Ok thanks, that dimension should be on the outside of the food can, but on the inside

rim of the paint can, am I cor

△ ▽

• Reply •

paul beard • 2 years ago> Ruaridh

A 540 ml can is perhaps what to look for. And then measure the outer rim of

the food can, and the inner rim of the paint can, as you deduced.

△ ▽

• Reply •

Ruaridh • 2 years ago> paul beard

Ah ok thankyou

△ ▽

• Reply •

Ruaridh • 2 years ago> Ruaridh

rect in thinking that thanks

△ ▽

Share ›

Share ›

Share ›

Share ›

Share ›

Share ›

Share ›

Share ›

Share ›

• Reply • △ ▽

• Reply •

paul beard • 2 years ago

I made one of these this afternoon: took an hour or so, plus USD2.99 for the paint can (local

hardware store vs big box).

https://www.flickr.com/photos/... and the next one in my stream (Flickr is down at the moment but I

had that one cached) show what mine looks like.

Looking forward to trying it out. A handful of dryer lint, maybe some wax-infused cardboard as

surefire starters, but it doesn't seem to need more than that and does it ever get hot…wow.

△ ▽

• Reply •

Bogeyboyz • 2 years ago

Is the 19oz can supposed to be the same height as the 1qt can, or should the 19oz can be shorter

to allow the airflow through the bottom holes on the 19oz can?

△ ▽

• Reply •

wabernat • 2 years ago> Bogeyboyz

The 19 oz. can is shorter. It should press-fit nicely in the underside of the paint can's interior

rim creases, which will keep it above the bottom rim of the paint can. The 19-oz. can gets

some standoff from the ground, but not enough to prevent charring if, for example, you set it

up on a park bench.

△ ▽

Subscribe✉ Add Disqus to your site Add Disqus Addd Privacy�

Share ›

Share ›

Share ›

Share ›