Improving the Tibetan dung-stove with wire coat-hangers

Liz To has designed a coat-hanger-based disassemblable stove for Tibetan nomads who cook indoors. It's a clever way of recycling one of the more pernicious waste products of western society (coat hangers) and relieving one of the worst health problems faced by Tibetan nomads (indoor pollution from dung fires). Apart from the rather unfortunate orthography (it's called "thab." -- all lower case, with a superfluous period), this is just great.

thab. is designed for Tibetan Nomads who live and cook inside tents. For cooking, they usually use the three stone cooking method however that causes health issues. They use yak dung as their cooking fuels.
They often boil water or soup therefore thab. must be strong, durable, efficient, safe and inexpensive.
Tibetan Nomads travel from one place to another every few months therefore thab. is designed to be disassembled so it can be portable.

thab. - designed by liz (Thanks, Avi!)

I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.

MORE: design • Gadgets • poop • tibet

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The World Health Organization’s website has some interesting information on indoor air pollution from cooking fires, which is far from just a Tibet problem. Worth a glance to go beyond the somewhat non-cited stats on the thab. page

http://www.who.int/mediacentre/factsheets/fs292/en/index.html
http://thisisonlya.blogspot.com robcat2075

Cooking with dung.

My grandfather was a minister in Minnesota around 1900. In his memoir he recounted having dinner with one farm family and watching the wife prepare dinner by cooking with one hand and using the other hand to feed the stove fire from a pile of cow dung brought in for that purpose.
nixiebunny

Coat hangers are one of the better “found” construction materials out there. Much stronger than baling wire. They hold their shape well and can be formed into all manner of useful items. We hardly have any left in our closet, as I’ve used them for everything from costume cheetah tail supports to Jacob’s Ladder electrodes.
- petertrepan
  
  Don’t forget bowtie antennas. You can make a homemade bowtie antenna with coat hangers that outperforms anything bought from a non-specialty store.
- fuzzyfuzzyfungus
  
  Even if they weren’t so useful, pieces of mostly steel with a little protective varnish or similar hardly seem like terribly pernicious items by the standards of the contemporary waste stream…
  
  Compared to say, plastic bags, they are much more recyclable and don’t disperse nearly as readily. They tend to be re-used a moderate number of times, and they don’t contain anything terribly unpleasant even if subject to exposure to the elements or crude recycling procedures.
- wrybread
  
  I agree that coat hangers are very useful, but aren’t they a *lot* harder to work with than regular bailing wire? And much much much harder to transport? For these reasons I’m guessing the nomads would greatly prefer using bailing wire, since they’re going to be disassembling these things when they move.
  
  And of course one could argue that coat hangers are cheaper (free) than bailing wire, but something tells me once you transport those coat hangers to Tibet you’ve lots any cost savings and then some.
  
  And are coat hangers really such a “pernicious” problem? This whole coat hanger angle, combined with the ridiculous name is really setting off my shtick detector.
  
  I’d be really curious to hear what the nomads think of these stoves, and whether they wind up actually using them after a month of trials.
  - Antinous / Moderator
    
    Wire escaping captivity and being ingested by cattle is a well-known problem. Not sure if a yak could gag down a chunk of coat hanger.
dragonfrog

Wow, the extraneous period really does make it difficult to read.

“They often boil water or soup therefore thab.”

Wait, what does that sentence even mean? Oh, I see. Sigh. It’s only four pixels, but it’s tremendously disruptive.
- http://www.facebook.com/profile.php?id=557683737 Adam Greenfield
  
  I don’t understand the point.
waetherman

This is a fantastic design – very well thought out for both economic and health impact on local communities. I do wonder though about the amount of reduction of pollutants – does the “combustion chamber” really increase the temperature to the point where it burns off more toxic gas? what about particulates? I can’t imagine it actually does anything about soot and such, and that seems to be the biggest cause for COPD. In other words, venting and education would seem to have greater impact.
- KWillets
  
  The rocket stove design has been studied quite a bit, and yes, it does reduce particulates.
- fuzzyfuzzyfungus
  
  Fuel sources with high levels of contaminants are a different matter (ie. the sulfur or mercury present in some coal isn’t going to get warm and fuzzy no matter how well you burn it); but if you are dealing with some largely benign organic fuel, completeness of combustion makes a big difference.
  
  The imperfect combustion that occurs at lower temperatures and/or under inadequate oxygen conditions can produce a grab-bag of nasties. Particulates, carbon monoxide, aromatic hydrocarbons, and so forth. The closer you get to complete oxidation of the material, the closer you get to the Chem 101 ideal of CO2+H2O as the outputs.
- KWillets
  
  To elaborate a bit, the combustion chamber often reaches over 1000 F, enough to ensure that almost all fuel will oxidize if mixed with oxygen. Part of that high temperature is due to reducing the flow of excess air which cools the fire, and part is due to insulation of the sides using, eg, porous ceramic or rocks with airspaces as in this design. It also relies on a continuous feed of small amounts of wood or dung to avoid flooding the stack with excess fuel.
  
  I believe most of the remaining pollution (there is still a small amount) is due to incomplete mixing of fuel and air. As it happens, hot gases are more viscous than cold ones, so the hot combustion section has less mixing than one might expect.
  - waetherman
    
    Thanks for that info; very helpful
- chellberty
  
  For anyone looking for more information on rocket stoves and their efficiency –> https://www.youtube.com/watch?v=HWM3BELk8Uo
SamSam

It’s really annoying. to read sentences that just seems to end randomly.

I’m guessing there’s some reason it for the name that relates to Tibetan nomads, but they don’t seem to explain it on the site.
http://twitter.com/fossilfuels Funk Daddy

Why is she sticking the S’mores she just made in with the dung?
http://thisisonlya.blogspot.com robcat2075

And no one seems to be addressing that they are cooking with dung. As if that were a completely benign practice. Do Tibetan nomads have suitable supplies of clean water to wash with after their contact with the dung?
- AviSolomon
  
  FYI dung is sterile, I’ve plastered village mud hut floors with it every day to get a clean new floor – sure beats washing tiled floors:) Also, the Tibetans would be using dried dung cakes in the stove.
  - sarahnocal
    
    Dung is sterile? It’s actually full of e coli, parasite eggs and all sorts of noxious stuff. It’s POOP!
    - AviSolomon
      
      We’re not talking about human poop. Have you ever been to a village in India?
      http://www.persee.fr/web/revues/home/prescript/article/paleo_0153-9345_1998_num_24_2_4677
    - Antinous / Moderator
      
      It’s POOP!
      
      Which most of humanity has used as food, fertilizer or a building material for most of history.
      
      It’s actually full of e coli, parasite eggs and all sorts of noxious stuff.
      
      What ever the yaks have, the people who live with the yaks also already have if it’s transmissible to humans.
  - fuzzyfuzzyfungus
    
    Dung is hardly sterile (your intestinal normal flora probably outnumber you, cell-for-cell); but most of the microbes involved aren’t necessarily human pathogens.
    
    Also, if you live in the treeless plains, getting to cook your food is probably a net health gain, even if you do catch the occasional bug.
    - http://www.facebook.com/profile.php?id=557683737 Adam Greenfield
      
      Even when dried?
    - AviSolomon
      
      It’s COW Dung:)
      http://vimeo.com/14033621
MossWatson

Is this essentially just a rocket stove surrounded by stones for support?
http://en.wikipedia.org/wiki/Rocket_stove
- KWillets
  
  Yes, it appears so. The L-shaped clay combustion chamber is actually the key part. Any metal in that area will melt or burn out fairly quickly, so I don’t see the point of the inner wireframe, except to establish the shape before textures are applied.
  - AviSolomon
    
    Liz To’s video gives a better idea of the stove’s construction:
    http://www.youtube.com/watch?v=Xev_dWT2DD0
http://profile.yahoo.com/STV76PTYDXBEJ6W7CTCEJ6RSNE SMichaud

I have no idea why there is a period about “thab”. It is usually transliterated just as “thab”.
Tibetan orthography is notorious for having silent (although they change the pronounciation) initial letters and ending letters.
It makes English orthography almost look rational.
sarahnocal

”one of the more pernicious waste products of western society (coat hangers)”

REALLY? I don’t think I ever throw away coat hangers, and I seriously doubt that it is even in the top 100 of pernicious waste products. Srsly.
- pKp
  
  It’s. A joke.
- http://www.facebook.com/profile.php?id=557683737 Adam Greenfield
  
  http://www.youtube.com/watch?v=XOILKHmZBwc
  - KWillets
    
    I confess this story gave me a vision of Joan Crawford travelling to Tibet to deliver the coat hangers (in a compost-powered car).
RedShirt77

How does three stone cooking method cause health issues? How does this stove solve the problem. The implication seems to be about smoke but this stove has no chimney. Why does this entry seem like it went through a bad translator?
http://www.facebook.com/profile.php?id=10135598 Ben Harper

Nobody ever wants to hear from the grammar police, but as I see this error constantly, I thought I’d speak up.

“More” is not a less agressive form of “most.” It’s used to form comparative adjectives or adverbs, whereas “most” is used to form superlative adjectives or adverbs. Use “more” when comparing two things, and “most” when comparing three or more. Coathangers are “one of the most pernicious waste products of western society.”

The interesting thing about this particular grammar error is that it’s typically made by the intelligentsia.

BONUS ROUND: People use comparatives as meek superlatives all the time! Can you find the commenter who committed this grammar sin in this very comment thread?
- alxr
  
  The Google Books corpus shows ‘one of the more’ becoming more common over the 20th century, seemingly stabilising in the 70s at roughly a tenth of the frequency of ‘one of the most’. That sounds to me like a fairly established usage, even in an corpus made up of (presumably) edited sources – I’d expect to see higher frequencies in conversation, for example.
  (Also, I’m not convinced that ‘one of the more pernicious products’ and ‘one of the most pernicious products’ are truly equivalent, at least to my ears.)