Nov 20, 2010

Homemade woodgas backpacking stove

This afternoon I built my first woodgas backpacking stove. I must say, it works pretty damn well. I gave it a test run in the woods behind The Cloisters here in upper Manhattan. It boiled water in less than 5 minutes and I only used a handful of tinder. The environmental impact from this type of stove is virtually nonexistent and its a great piece of gear for the minimalist backpacker. It's great to be able to carry a small, light stove like this and not have to worry about bringing fuel canisters for it. All you need are dry sticks and you're all set. I made the stove using a small soup can and a piece of scrap stainless steel I pulled from a dumpster at work. I'd like to thank a few bloggers out there for motivating me to make my own woodgas stove: Heber in particular for his detailed construction notes. “Stick” for his videos of his version of the woodgas stove (by the way, check out Stick's Blog, it's an incredible resource for backpacking gear, tips and information) Lastly, I want to thank Ray Garlington who designed the stove. A quick video and pictures of the construction are below. The video is geeky, I know, but it was actually fun to make. The next time you see me using this stove I will be deep in the Catskills.


Above: I love/hate how noisy the Henry Hudson Parkway is in this video.


Above: This is the top of the stove. Note the four vents near to top of the stove. These, work in conjunction with the vents at the bottom of the stove to facilitate what is called an "inverted downdraft gasifier". In short, this enables the fire to burn from the top, down to the bottom of the fuel source (tinder).


Above: This is the bottom of the stove. The screen keeps the tinder off the ground and allows air in through the vents which double as a support for the screen.


Above: I used a coffee can to make a wind screen. This prevents the fire from being blown out when it's windy (it was windy today!) and also works as a chamber for preheating the air around the stove, further aiding combustion. The coffee can is an ideal height for use as a pot support as well.

8 comments:

stick13 said...

Mike, great job with the stove. Looks like it worked out great. Thanks for mentioning my blog too. I am going to add your blog to my blogroll as well.
About the stove, how long did it take before everything was burnt out? This was one of my issues with these types of stoves. It seemed like I would load mine down with wood, but then I would have to wait forever for it all to burn out enough to scatter the ashes without concern for another fire starting. And it didn't seem like I could necessarily counter this by just putting a little bit of wood in because then it would never burn hot enough to get the water boiling.
My other issue was the soot. It didn't look like your pot had much soot on it after boiling the water in the video. My concern here is that I would have to pack up those sooty items back in my pack with gear I try to keep clean. Speaking of pot, what kind of pot was that? I haven't seen one shaped like that. Do you have a stuff sack for the set-up?
Anyway, sorry for all the questions. Again though, congrats and thanks for the shout-out!

Heber said...

Nice video! I haven't made the jump to posting videos on my blog yet but perhaps I'll have to try it one of these days.

I'm glad my plans were helpful to you.

I might be able to answer some of stick's questions.

Once the stove is lit it seems to go for 8 to 10 minutes with a good flame. Enough to bring two to three cups of water to a roiling boil anyway. At that point the flame weakens and dies and you are into the charcoal phase and that does take perhaps 15 minutes to go completely to ash. But at that point I'm re-hydrating my food and then eating it. By the time I'm done eating there's nothing but ash in the stove.

Soot (or, more precisely, creosote) is definitely an issue anytime you use wood as a fuel. When I backpack with this stove I keep the pot in a separate stuff sack from the stuff that I don't want to get all black.

Michael O'Hara said...

Hey Stick:

Heber's comment is dead on. I had nothing but ash after about 15 minutes. I dumped it out and rubbed it into the dirt with my shoe.

I don't have a stuff sack for this set up, but I think I'll look for one tomorrow downtown. There's an EMS Store I need to get to.

As for the pot, I picked it up at an Army Navy store. It's some type of military pot. It's shaped like an old army canteen. It's not light and it's made of steel but I don't care if it gets black. Funny thing about it though, it got black but it doesn't rub off... I'm not complaining.

stick13 said...

Thanks for the clarification on the time frames. I may have to drag my DIY woodgas stove out and play with it some more. Then if it doesn't work correctly still I could always build another one. Coffee cans and soup cans aren't hard to come by, and I bought enough hardware cloth to last a lifetime for my use.

recumbent conspiracy theorist said...

Hi Mike,
This project looks almost too good to pass up. I got enough raw materials from my last chili cook to make at least 3 of these stoves. And what 9 year old wouldn't love to play with that thing in the back yard.

Michael O'Hara said...

Hey RCT:

Yeah I think you should definitely give it a go with your boy. Explain the theory to him, build it with him and then fire it up! Make some soup or something. Definitely check out Garlington's site for the theory and operation of the stove; he is the inventor. Heber's blog has great contruction details.

Mike

Doug said...

What's that gray thing you put in with the twigs. Something to help them light?

phattire said...

Doug:

Yep, that's some drier lint. Great fire starter!