The Magic Cookpot

Guest Post by Willis Eschenbach

This one is for fun and also for real. The theme of this post is “There’s never enough time.” I worked in the villages of the developing world off and on for a number of years. A recurring issue is the inefficiency of most stoves. The simplest is the “three stone” variety, made with three stones to put the pot on.

Figure 1. An obviously ancient three-stone fire with a modern cookpot in Tanzania. Photo Source 

This is hugely wasteful of fuel, particularly in lands where wood and even branches and twigs are scarce. Among my known defects is that I’m an inventor. Over the years I’ve worked on making and designing a variety of stoves to try to improve stove efficiency. As a result, in one of my peregrinations around the web a few days ago I was intrigued to stumble across the “Kelly Kettle”.

The Kelly Kettle was used in Ireland by the shepherds to brew their cuppa tea. Here’s one at work on a beach somewhere.

Figure 2. Kelly Kettle cooking on a beach. Note the fire coming out the chimney.

The brilliance of the plan is that the water in the kettle surrounds the fire. I looked at that, and my inventor’s soul rose to the fore, and I thought “Man, I could make the radical Dutch Oven using that plan. Here’s what I think it might look like.

Figure 3. What I call the “Magic Cookpot”. Note the split (two part) lids, one of which has been removed, flipped over, and laid on the ground for clarity. Lids will have handles in the final version.

And here’s a cross-section:

Figure 4. Cross-section of Magic Cookpot without the lids. 

No good to throw away waste heat, so the Kelly Kettles have a pan-holder that fits in the chimney to allow you to cook another pot of food on top.

Figure 5. Kelly Kettle with cookpot. Source.

Looks good to me, so here’s my version of the same. This would allow you to cook soup or stew and have a frypan on top …

Figure 6. Potholder inserts into chimney of Magic Cookpot.

OK, advantages of this plan:

• Efficiency, efficiency, efficiency. Even without cooking anything on the top, this will heat water with less fuel than any design I’ve ever seen.

• Cost. Because the stove and the cookpot are one, you don’t need to buy both.

• Portability. It can be moved easily.

• Adaptability. It can use a variety of fuels, including a propane burner.

• Speed. It will heat water fast.

As I mentioned, the theme of this post is the theme of life—there’s never enough time.

In a perfect world, I’d take this idea and run with it and make a big difference in the amount of wood burned around the planet. I don’t have time, I have a bunch of other projects going on. But I’d hate to see this idea die, it’s a really good one that could make a big difference. So I figure I’ll cast the idea free on the web, make a gift of it to the world of stoves, and see what becomes of it out in the greater marketplace of ideas.

How could this rough plan be improved? It needs a damper to control the draft, and some kind of flap to control the air intake. You could probably increase the heat transfer (fire to liquid) by putting some spiral fins up the chimney. This would increase the surface area and transfer extra heat to the cookpot.

In any case, there it is, and I encourage anyone with the time and energy to become the champion of the idea. You’ll make a name for yourself and have women blessing you all around the planet. All it needs are a couple of sharp Brazilian or Indian or Chinese (or European or American) college students who’d like to make a difference in the world.

w.

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174 thoughts on “The Magic Cookpot

  1. Good thinking Willis – although there are some fairly good designs out there already – e.g. the Sierra Stove which doesn’t use the Kelly Kettle principle but instead uses a battery powered fan to blast warm air onto the fire and burn the fuel much more efficiently – http://www.digitalmarketingusa.com/ZipStove.html
    I think there’s another similar product on the market also.

  2. Excellent…I’ve seen parabolic mirror solar cookers here in australia.
    Tools are what we need, better tools…I fear part of the green religion is technophobic.

  3. …while decoupling all that waste cash from the bottlomless money pit of CAGW and applying a fifth of it to providing clean water to put in the pot….

  4. Willis
    We have had a similar working one like that in NZ for many decades (thermette), predates the great depression if Im not mistaken.
    http://www.jackmtn.com/simplog/gear/thermette-vs-kelly-kettle-challenge/
    Im also not sure about trying to control the fire with dampers etc, they never last and also they starve the fire of air creating smoke which is both wasteful fuel and not so flash for health. Best way is simplest way and for my money I would be controlling heat by fuel addition. But its good to see if there are any other ideas that might work and be robust.

  5. These have been on sale in the UK for decades.
    Would not a better idea be to actually supply these impoverished peoples with a cheap form of energy at the push of a switch. It is called Electricity and it has done more to help peoples development than anything else.
    Oh! I forgot that would mean using coal, that cheap plentiful power source, which would mean an increase in anthropomorphic produced CO2!

  6. The whole concept, takes me back to my childhood in Australia, and the old chip heater that we had in the bathroom, it was basically a tall light metal cylinder with an internal copper tank on the upper inside. There was a cast iron door and frame for introducing small woodchips, paper, and internal cast grate that stopped the coals from dropping down into the ash tray.
    Basic operation was to get a fire going and run cold water into one end of the internal copper tank and the other end was a spout outlet to run the hot water into the bathtub, when the bath was a suitable temperature the children all got put through the bath.
    Woe betide you if you set too hot a kindling or chip fire and got the internal circular tank too hot and steam developed, sometimes bursting the copper seams and the sore backside for doing it taught you not to repeat the exercise!!
    Those were less complicated days – good luck with your idea, it sounds good. When they put us back into the dark ages, maybe we will all need such a cooking pot if we are allowed (a) to be trusted to operate it (b) to fuel it (c) to own or possess it (d) rent it from the ruler, with suitable carbon indulgences.

  7. On a trip to China I was treated to traditional food from the north of the country. They brought out a “stove” very similar to figure 4 in which you cooked your own bits of food in the boiling water. The boiling section was also partitioned so that you could cook in water or sauces at the same time. I guess the question is why this device has been invented in many places around the world but not in Africa (or has it and merely been forgotten)?

  8. Neat idea, Willis. However I fear the “Kurd” has it on the nail head when he talks of decoupling monies from CAGW. I fear little will be done to eradicate poverty & hunger & disease around the world via CAGW, despite the paltry sums required to do so by comparison. The “realists” are negative people, always seeing the “problems” with this or with that, you know the type, “it’s all very well you saying that but I’m a realist!”, whereas the “realistics” are practical positive people, those who see the problems & come up with solutions to those problems! Wish I was as clever as you though! 🙂

  9. I have a kelly kettle and it is quick and easy to use. It’s only draw-back is that if you have a good fire burning in it, when you take the kettle off to pour out some water, the burning twigs or whatever will fall over making it difficult to get the kettle back on the stove.

  10. Terry,
    When I was a teenager in the mid seventies (in NZ) we had a Thermette that we took on regular family picnics. It would run on almost anything as long as the fuel was at least semi-dry and would boil about 4 to 5 litres of water in just a few minutes. Very good for coffee, tea, soup etc, and washing the dishes.

  11. The desert soldiers made “Benghazi Burners” that used what ever fuel they had to hand. Thermette developed from that.

  12. KenB says: (May 10, 2011 at 3:10 am)
    The whole concept, takes me back to my childhood in Australia, and the old chip heater that we had in the bathroom…
    That’s where it took me, too, Ken. Absolutely brilliant; and luxurious. Ours was a “Malley” from memory. Bit of newspaper, some wood chips or kindling leading to fearsome bubbling and spurts that became a glorious hot bath on the coldest night.

  13. DocD says:
    May 10, 2011 at 3:24 am
    On a trip to China I was treated to traditional food from the north of the country. They brought out a “stove” very similar to figure 4 in which you cooked your own bits of food in the boiling water.

    Commonly known as a Steamboat. See for example http://uktv.co.uk/food/item/aid/511539

  14. BTW: If you have a gas water heater you can find the spiral fin design in the center flu. It’s a drop-in piece that slows the exhaust gas. It increases heat transfer, but also reduces the amount of carbon monoxide to near zero.

  15. Here’s a couple of images of the ultralightweight kelly kettles and alcohol stoves I make from beer and energy drink cans for my backpacking expeditions.
    http://cache.backpackinglight.com/backpackinglight/user_uploads/1218618150_07167.jpg
    Capacity two cups, boils in 3.5 minutes using 12.5g of 95% pure alcohol. Efficiency is 63%. The kettle and stove setup weighs under 3oz.
    http://cache.backpackinglight.com/backpackinglight/user_uploads/1219072939_07233.jpg
    Capacity 1 cup, boils in 4 minutes is 6g of 95% pure alcohol. Efficiency is around 67%. The kettle and stove setup weighs under 1 1/4oz
    I also have a 4 1/2oz wood burning version made from an aluminium drinks bottle.
    http://cache.backpackinglight.com/backpackinglight/user_uploads/1200954209_04394.jpg
    The double skinned gasifying woodstove it sits on is made from a syrup can and weighs 5oz. I now make titanium woodstoves from 0.005″ material. They weigh under 2oz.
    Finally, and not for the faint hearted. Me on a snowy mountain top demonstrating the all weather applicability of the design:
    http://cache.backpackinglight.com/backpackinglight/user_uploads/1288706825_32605.jpg

  16. As the stove and the cookpot are one, when you lift the lot to pour sloppy food out you have an uncontained fire.
    A tin for making ring shaped cakes like angel food cake would be a basic first step – the bit that makes the hole in the cake being the chimney.

  17. Willis? Excellent idea, one small change, though. Make the firebox/chimney and the cookpot two separate pieces, so that you can lift the main cookpot off of the firebox/chimney. You can still use the chimney top pan holder, and you could use multiple main cookpot sections on a single chimney set. Also, the chimney could be used stand alone as a heat source while not cooking, if needed.
    I have years of experience cooking over all manner of heat sources in in all manner of conditions. Hell, used to cook C-rations on the exhaust manifolds of trucks in US Army, so I am always up for something new!
    Hope to see these for sale soon.

  18. I have a Russian Samovar – it uses the same principle – it heats water very quickly and needs little fire. The Samovar has a long and wide history.

  19. I already came across this as a recognized issue in the news 20 years ago and development projects had been initiated to tackle the problem…

  20. The advantage the three stone fire has is that stones are available everywhere for free. That is an advantage that is going to be hard to beat.

  21. In stoves, you need a hot combustion chamber to burn all gases (the more smoke, the less complete combustion). That’s how best rocket stoves work : with well insulated walls and a good compromise between exhaust gas temperature and speed (the limit being that draft force doesn’t extinguish the fire).
    So I suspect the “Kelly Kettle” to be of pratical use but not very efficient because of by-design cold walls. If you want to use it for cooking, you need to add water even if you don’t want hot water otherwise the walls’ temperatures rise rapidly way over 100°C and the reservoir won’t last long if it’s made of tin.

  22. Nice and good looking. “Form follows function.” But for emergency water purification or even routine camping, it probably wouldn’t pass the Environmental Impact Assessment./sarc [Me, I really don’t care any more, given the “quality” and politicization of Central Governmental services. I’ll look after the “environment” myself.]

  23. A circular cross-section of the chimney presents the least possible surface area in contact with the water. You can increase that by flattening the internal part of the chimney while maintaining the same cross-sectional area.
    Gas water heaters have a baffle in their internal chimney that causes the flue gas to swirl and bring hotter core gas to the contact surface. It’s a simple strip of sheet metal that has spirals and ripples stamped into it.

  24. An excelllent design and always enjoy your posts.
    While AGW receives a lot funding for uncertain future risks, spending a small amount on technologies that people use daily could have real benefits. Given the world’s use of dung, wood, and charcoal, a more efficient stove could have dramatic health, energy, and the environment impacts today.
    A Franklin Energy Project to unlease the creativity to design a new Franklin Stove may be a way to achieve that goal. The Franklin Stove was considered revolutionary and it dramatically increased energy efficiency and safety. Like you offering your stove design to the market, Franklin felt his was a public good and he also made it available to all. (Bet you haven’t been called Franklin in a while?)
    Coincidentally, I learned yesterday in October 2010 at the Clinton Global Initiative, Hillary Clinton pledged $50 million dollars to a UN sponsored Clean Cookstove initiative. Julie Roberts is the Ambassador and it seems to have become both a government project and a Cause Celeb. A review of the program announcement
    (http://aidwatchers.com/2010/09/what-hillary%E2%80%99s-cookstoves-need-to-succeed/) had lots of comments, primarily from former Peace Corps members, that were generally negative on the whole idea primarily for two reasons. The design had to meet the cultural needs of the local cooking style and it had to be really cheap, possibly made of local materials by locals. Past efforts had failed in both of these areas. Any thoughts you or others may have on those comments or ways to advance this worthy cause would be greatly appreciated.
    I wonder what Ben would have thought of AGW?

  25. I have anecdotal evidence of how heating from the inside is much more efficient. I make metal electroforms over hollow plastic patterns and the patterns have to be removed from the inside when completed. You have to work really hard to heat the metal from the outside to soften the inside pattern but if you can get some steam on the inside of the form, everything heats really rapidly. The Kelly stove looks like a great way to use fuel much more efficiently and in my experience, heating from the inside out is much more effective.

  26. Great post, and you got me thinking!
    I took your idea and ran a bit with it (it’s a 3D PDF – click on the image and you can rotate, zoom, and pan):
    1. Added an air insulation layer on the outside to better insulate the hot water/liquid section.
    2. Contoured the inside chimney to shape like a chiminea, a very efficient shape for drawing constant air through a fire.
    3. Added a small lip to the half-lids, so you could use them to keep things warm over the hot water.
    4. Added internal radiators to better couple the liquid to the heat in the center.
    The top would work the same as you showed, or you could use a small insert “frying pan” attachment that would route the heat across the base and out the sides, and end up cooking like a wok (from the center and sides as the fire wraps around the pan).

  27. DocD,
    That’s called, surprisingly enough, a “hot pot”. Usually one side has a spicy, fiery pepper based broth, the other has chicken or mushroom broth, to give you hot and mild. Then you bring it up to boil, dunk in thinly sliced meat and vegetables, and in 20 seconds you can eat!

  28. Willis: you are missing something very important – all the IPCC’s witch doctors are convinced that increasing global temperature of 0.007 oC p.a. (Gistemp 1900-2000)is quite enough to boil some 3 billion kettles of water a day and generate enough water vapor to raise the climate sensitivity for a doubling of [CO2] from 1 oC to 3 oC or even 6 oC.

  29. Thats very nice but as I recall during my service in Her Majesty’s Armed Forces in the dim and distant seventies we had something very similar (very crude construction by comparison) called a Benghazi, and from what the oldies told me they had been in use ever since the war in the desert in the forties.

  30. I have used a thermette since the 50s. They are incredibly efficient at boiling water with a minimum amount of fuel in almost any conditions, rain, wind etc.

  31. My lady is Thai and they cook outdoors some times like we have BBQ’s. They use a simple earthen ware pot with feet and holes in the bottom as a grate. A couple of hand fulls of charcoal is the fire. Atop this sits an annular pot full of water, the central chimney is grated. The vegetables are cooked in the water and meat strips cooked on the chimney grate. Two hand fulls of char coal I have seen feed ten people, then when ever one is fed the coals are tipped out and doused with water, any charcoal left is used next time. I have eaten in deepest China in an old fashioned restaurant where these are built in to the table and you cook your own food. Very efficient. Your cooking device is excellent Willis but too high tech and needs to be 17th century to make a difference. so that the local artisans can make it easily.

  32. good one Willis.
    the Thermette seems to have it already done though.
    you know, why isnt ANYone asking why?
    there are so many folks who havent progressed past 3 rocks?
    I mean come on, a few handsfulls of mud and some more rocks makes an efficient oven that warms, and chimneys are easy to make with mud and even a hollowed ceiling to let smoke escape was invented cenuties ago.
    the smoke preserves seeds and food and deters mozzies so maybe? thats why they are willing to keep doing this?
    now if Gates and all the other bignoting zillionaires really wanted to help..theyd run a education and supply of similar useful things. will they? doubt it.

  33. This is why I love reading at WUWT. Can-do attitude where a low-tech but highly practical invention DOES deserve attention here! One cool technology I have always thought about that might work any country are water powered clock mechanisms. You could water power the solar tracking for photovoltaic systems or solar furnaces. Thanks for this neat invention, it may end up helping the world, we should call it the Eschenbach Crock.

  34. All very fine and all very well. I have no problem with improving the state of the art and health of humanity. Problem is that some people latch on to this and run the wrong direction with it. In specific I am talking about (Robert) Jeremy Grantham of GMO LLC. who wants to put a carbon tax in to finance these in 3rd world countries.

  35. Great thread! You seem to have reinvented the Thermette, but I was delighted to learn about that. Will send a link around to family members who are campers and hikers (and even a ‘sustainability’ nut or two).
    Don’t disparage the three-stones method, though. Nothing is easier when traveling. You don’t need to tote anything except a pot. The only challenge is to find some stones, and some dry tinder and sticks.
    /Mr Lynn

  36. One of the reasons I read The Chiefio’s blog is because I love the survival stuff. It just might come in handy one day, but NOT because of global warming. Thanx Willis and posters.

  37. Good post, Willis, and seems to have got the creative juices and the memories flowing.
    Like most Kiwis, I grew up with the Benghazi Boiler which later became the Thermette. Almost every family had had one of these for a hot cuppatea on a rural job or at the river/beach/down the back of the family farm before barbecues became universally popular.
    If your updated design were to be made by village craftsmen, I would suggest that using ceramics (fired mud) as a construction material may put the device within reach of a huge consumer group.

  38. I just don’t see how you can get the production costs down low enough to be price competetive with the 3 stone model pictured in the article. 😛

  39. If I missed it I apologise, but I couldn’t see any place to start looking for similar devices in the UK.
    What I would like to source is something like a 20 litre (4 gallon) catering urn.

  40. Some nice stoves here, but don’t forget the simplest way to make a fire more efficient: dig a small straight-ish sided hole, and build the fire at the bottom. Then simply put your pans on top. Nowhere near as efficient as surrounding the fire with working fluid, of course, but if you’re calculating efficiency improvements, you should start from the baseline of what’s easily achievable with a little thought but no additional resources.

  41. Shanghai Dan… yeah that was it! I remember the hostess saying it was “hotpot” now. I probably misremember the water/sauce thing, it was a few years ago. Interesting what they gave to dip in the broth to eat…

  42. Not quite off topic, but a large step up from simple cooking, is the MultiMachine. It’s based on using discards from automotive products to build machine tools which can be powered by men, donkeys, water, wind, or electricity. The idea is to build rudimentary tools which can be used to build better tools.
    I’ve been working with a group which has a school in Kenya, trying to get a shop started where the studies in math and science can be applied. For further information see:
    http://groups.yahoo.com/group/multimachine/
    Getting people out of the stone age isn’t as hard when they learn how to make tools to make tools.

  43. “hugely wasteful” might be somewhat of an exaggeration, no? The cost of this thing (has to be imported) could buy you a couple of cubic meters of wood, enough for several years of hugely wasteful cooking with 3 stones. Not much wood is needed to cook anything by any extravagantly wasteful method, and although AGW crowd would disagree, it grows back. As someone that likes to grill things (even more wasteful), I usually get by with a few branches of wood lying around. And efficiency can be hugely improved by such things as described above.. some mud and some more stones. no need for high tech stoves. I somehow doubt that African villagers are as retarded as some people in the west think they are

  44. I’m a big fan of Willis, but this is a crock. Several people have mentioned one problem and that is costs. Who will pay? Between the politicans and the dictators, they will get their dirty hands on any project like handing out cooking devices. Oil for food-That worked great. What to use for fuel? Go to Haiti and try to find a small tree to cut and use-lots of luck there. So, who is going to supply the alcohol or charcoal? Rid the world of petty politicans and educate the people and they won’t need our help anymore unless they vote for thieves and politicans. Sorry I am so cynical . I would like to help and would if there was a truly good way to do it. That problem must be solved before the charity.

  45. Good one, Willis. Excellent info from commenters (the usual exceptional WUWT crew) to gather all the histories of efficient heating and cooking and pass them on to the next generation.

  46. It looks like this could be made locally out of clay. It needs a tap/plug at the bottom of the reservoir to draw off liquid without having to tip it up. (Or a ladle on bigger models I suppose)
    Pause for a moment though. If we are, quite sensibly, taking away the smoke on the grounds of health and efficiency; we need to ask, what else is that smoke doing? One upside of a bit of smoke with a grass roof (no hole) is that it seeps through and kills of insects, so the birds don’t tear up your roof to get at them. As long as the roof is high enough or internal volume large enough people live well under the smoke layer. What are the implications of and solution to removing the positive aspects of smoke?

  47. Ah, the old thermette of my childhood, nicely updated.
    We also have a similar device, a charcoal-fired steamboat (aka Mongolian hotpot). Great for entertaining – you prepare sliced vegetables (bok choy, spring onions, zucchini, carrot), small slices of beef, firm-fleshed fish (small shark is best), chicken, pork, mussels, cockles, abalone, prawns etc. Cook enough rice for everyone. Put the rice and the ready-to-cook veges and meats on the table.
    The hotpot is placed in the centre of the table when the charcoal is at bbq heat. (You need a stone or brick layer to protect the tabletop and if you’re inside, remove the smoke alarm!) Fill the bowl with chicken stock and provide sauces – chilli, soy, five-spice, whatever. Each guest has a plate and a soup bowl, a soup spoon, a fork and an open spoon made of woven brass wire, so that the spoon bowl is a brass net.
    Guests put whatever they chose in their open spoon and put the spoon end in the stock. Hilarious – the food promptly floats, so everybody fishes out what they can when it is cooked. It’s great fun and the taste is divine. The meal lasts at least a couple of hours.
    When all the food is consumed, the stock in the pot, by now highly flavoured by everything that has been cooked in it, becomes the last course. That’s right, the soup.

  48. send it to Steve Jobs!
    Add a bit of glass, smooth off the edges a bit and in a couple of years, we could all be proud owners an ipot.

  49. I kind of surprised no one has mentioned what materials would be used to build the stove. Obviously there would be several different styles. Alloys for the western user who needs weight savings over durability(every day use) and cheaper metals with a focus on durability for those who would use it daily. I am not familiar with all the alloys out there for the camper/outdoorsman, but for the daily user iron would seem to be best for cost and durability. This is a wonderful idea, Willis, kudos to you.

  50. You could incorporporate a tap into the body of it, fairly low down, so that hot water may be drawn off, without having to shift and tilt the unit. That would mean that you could continue to use another pan on top, undisturbed.

  51. great idea — the example looks like cast iron which would need to be seasoned and is inclined to rust — stainless steel would be lighter and easier to maintain but would lack the mass to retain heat. The fuel source is still the primary problem.
    As gross as this sounds, why not use human waste to generate methane and use the methane for cooking? Or, split water and use the hydrogen as fuel. Storing hydrogen is a problem but using it at point of use would work. Might be able to use urine and produce clean water and fuel?

  52. Excellent Post!
    My wife did Peace Corp in west Africa and currently manages a social projects department for an American oil company in west Africa. She came across a project that allows doners to gift a solar powered (Don’t write it off yet!) flashlight to villages in regions that are desperately short on fluel or places where poor fuel sources like trash are burned indoors . The light is needed in the evenings, and is bright enough to replace a roaring fire.
    https://www.bogolight.com/Articles.asp?ID=136
    I’d love to see a similar project set up where a custom designed and massed produced “Watts” stove could be gifted. The aim would be to reduce deforrestation (an ACTUAL environmental problem) and improve health. I’d much rather have one of these donated in my name at Christmas than receive another (choose one: sweater, tie, fruit cake, coffee table book, etc). Besides you’d never have to worry about accidentaly ‘re-gifting’ one of these to the original giver.
    If anyone would like to take off and run with this idea, I’d love to be a part of it.

  53. Old Goat says: May 10, 2011 at 6:58 am
    You could incorporporate a tap into the body of it, fairly low down, so that hot water may be drawn off, without having to shift and tilt the unit. That would mean that you could continue to use another pan on top, undisturbed.
    Oh yes? Would that other pan on top be a container of cold water … hot water my foot! Nice try, but it’ll never wash with the excise man.

  54. Yes, an ideal version of this, imo, would have an all-clad aluminum center that would extend from the top of the inner cone chimney along the bottom up through the top of the the outside walls. We wouldn’t want any hot spots while cooking, now would we? 🙂

  55. Of course, the three stone method has other purposes. The hefty rocks in the image at the top have a fair sized thermal mass. So although the cooking process is inefficient in terms of how much of the heat goes into the food compared to the rocks, it should be remembered that an integral part of the reason people use such big rocks is because they act as storage heaters, keeping the hut warmer throughout the night, after the fire is out.
    It’s rather like the reasoning people have for keeping their incandescant bulbs. They want their room warm anyway.

  56. good point tallbloke — the old bed warmer…
    This from 3 years ago but the problem is electricity to split the water which is inefficient. Although the car version in the video is using the 12 volt battery to do it so I suppose solar and battery storage might work in the bush. Addressing potable drinking water, sanitation, and conservation of energy in a holistic way would be amazing. Who knows, if this were developed the UNFCC might get off its duff and actually implement something that has a true benefit. Probably not but one can dream.
    [youtube http://www.youtube.com/watch?v=Zu-Hg6ntgqI&w=640&h=510%5D

  57. Sadly, in today’s environment, casting a novel idea afloat on the internet may only provoke the unscrupulous to capture it and attempt to patent it, thereby creating the irony of a situation in which the actual creator could be legally prevented from using his own idea.

  58. I love the comments and the idea, but the 800 pound gorilla that I see in the room is that the central heating idea makes it very hard to clean and cook anything in the water.
    It will work great for boiling water for tea, and noodles but that is about it. A pot is much more efficient to actually cook in and clean.

  59. Make a green version to include-
    Small wind turbine and solar panel to power fan to provide forced airflow
    CCS device fitted to the chimney
    CO2 sensor to calculate carbon footprint
    Software package to run on iPhone so green campers can monitor their footprint in real-time
    Sell above version via NatGeo etc to green people with more money than sense, use profits to subsidise the stripped down practical versions for those that would benefit.
    Curious though how design matches typical cooking and diets in areas that could benefit, ie whether it could be improved with options for roasting/grilling/baking.

  60. Hot water heaters work the same way as mentioned earlier. 75% of India and China still cook and heat with corn stover, wood, charcoal, coal trash etc.

  61. Tall Bloke, my brother from another mother!!! I have made camp stoves using various sizes of metal coffee and soup/food cans, for use with wood, charcoal, trioxine tabs and even candles. Have made candle lanterns from beer cans, one from a Fosters can that we used for several years.

  62. Nice design. You may want to consider posting it at http://bioenergylists.org
    Take some time to review the site. There is a wealth of information there, almost to the point of information overload. Your interest and insight would also be welcome on the Stoves list.
    @wcp2, It is not an exaggeration. A couple cubic meters of wood might last a few weeks for a family who must cook every day with it. A 3-stone fire tended by a skilled cook can be as efficient as many “improved” stoves, sometimes more efficient, given perfect conditions. The problem is that there are not many cooks whose priority is the efficient burning of wood and conditions are rarely perfect. Most improved cook stoves provide significant savings for the user and many are quite inexpensive. Yes, wood can grow back, if allowed to. In areas of high demand, wood is consumed at rates far higher than its capacity to grow back, like overgrazing. Time spent gathering fuel, and/or money spent to purchase it, puts a tremendous burden on the family, particularly women and girls. Most improved stoves also improve air quality which gives a significant health benefit. Any significant reduction in fuel consumption compounds the overall benefit to the family and society.

  63. Nuclear power is one hell of a way to boil water. – Albert Einstein
    I wonder whether nuclear energy is more efficient than other forms of energy. My more interesting thought is, if you have nuclear energy, do you need to care about efficiency optimization? Why should we worry about a lack of twigs to boil water, or dung? Is that the life we want?
    Japan is likely going to have a bit of shortage of electricity this summer because the Daiichi nuclear plants will be offline. Japan has quite a shortage of twigs to keep the Ginza lit. It also has a shortage of oil.
    The rest of the world does well when we develop technology that can be shared. Tech development requires concentrated capital and facilities to develop new ideas and manufacture new products. Spreading the wealth would limit our ability to develop new tech and would tend to diminish the quality of life for those at the bottom.
    This principle was evident during the Depression. Will Rogers said, “America is the only country where people drive to the poor house in their car.” Our poorest today live better than kings of 500 years ago. Go to third world countries and you will see satellite dishes on shacks. There are compact clean water systems being developed that will help prevent disease. Pharmaceuticals also help save lives all around the world. These drugs require almost a billion dollars each to develop.
    Social justice, whatever that is, will kill people. A true free market and a benevolent modern society will save millions of people suffering elsewhere. The way to do that is not to bring the top down, but to bring the bottom up. Life is not a zero sum game. Let the top end of society rise, and the bottom will go up too.

  64. Willis, I don’t think that the technology described here:
    http://www.jetboil.com/files/Helios%20Tech%20Brief.pdf
    would be of much use in the more primitive parts of the world but it is interesting. Backpackers want to carry as little fuel as they can so efficiency is important. I have one of their units which will boil water very quickly.
    It does seem that cast iron pots could be made with fins on the bottom and up the sides radiating outwards. The pot could rest on the fins instead of on rocks, etc. If the fins where deep enough, there could be space in the center for a small fire. The heated air would move up through the fins and out which would tend to draw cool air in at the bottom for the fire. That would be somewhat like the draft of a chimney. The cool air moving over the fins at the bottom would be pre-heated which might improve the combustion efficiency. There would probably need to be a base so that the fins would not lose heat to the ground. Or the fins could rest on rocks with only a small area of contact. Just a thought.

  65. As a former kitchen boy, I wonder about clean-up. Even if water were readily available, I might soon be cursing the inventor, especially if the cook burned the stew that evening. I now have twice the surface area to clean.

  66. We cooked a one-pot supper for a family of six on a tiny camp fire in a hole in the sand while on the way to Ayers Rock in the NT of Australia back in 1984. A strange couple in a massive converted school bus camped near us. They used a moped to drag back a huge chunk of dead tree, lit it, and left it smouldering overnight, and left it still smouldering (under a live tree and surrounded by spinifex) when they departed the next morning. We felt we had to extinguish the remnants before our own departure. The lesson: with care you do not need to use much fuel to cook for a family, even without a stove.

  67. The further lesson, of course, was that there are always wallies around who do not care for the environment, and for whom wastefulness and pollution are a way of life. We were absolutely staggered at their attitude. It goes without saying that they also polluted the environment with their loud radio and ghastly muzak.

  68. John from CA said: “As gross as this sounds, why not use human waste to generate methane and use the methane for cooking?”
    A good idea. In Nepal, India and China and elsewhere human and animal waste is made into gobar gas.


  69. the Dakota hole fire place is much simpler. No special pot to carry and very efficient.
    The side chimney turns it into a blast furnace. It was used to keep wild fires from spreading on the plains in high winds. We used it to boil( with a grate on top) or to bake (putting the dutch oven inside) many years ago when I was on the staff at Boy Scout Camp in northern Minnesota.

  70. John Marshall says:
    May 10, 2011 at 3:03 am

    These have been on sale in the UK for decades.

    If by “these” you mean Kelly Kettles, yes, you are right. If you mean a cookpot like I imagined, I don’t think so.

    Would not a better idea be to actually supply these impoverished peoples with a cheap form of energy at the push of a switch. It is called Electricity and it has done more to help peoples development than anything else.
    Oh! I forgot that would mean using coal, that cheap plentiful power source, which would mean an increase in anthropomorphic produced CO2!

    Sure, that would be better, much better. And it would be better if the impoverished people lived in nice houses and had good food and medicine and proper schools. And ice cream. Lots of ice cream …
    Meanwhile, in the real world, the sad truth is that we can only advance one step (or one stove) at a time. Installing an electricity grid for an entire country sounds good, but the emphasis is on “sounds”. That’s a long, long ways from today. So I leave such lovely armchair fantasies to folks like yourself, I’m more interested in actually doing something practical for today.
    w.

  71. Mr Lynn says:
    May 10, 2011 at 5:32 am

    Great thread! You seem to have reinvented the Thermette, but I was delighted to learn about that.

    Nope. You can’t boil potatoes in a Thermette, but you can in my magic cookpot …
    w.

  72. wcp2 says:
    May 10, 2011 at 6:15 am

    “hugely wasteful” might be somewhat of an exaggeration, no? The cost of this thing (has to be imported) could buy you a couple of cubic meters of wood, enough for several years of hugely wasteful cooking with 3 stones. Not much wood is needed to cook anything by any extravagantly wasteful method, and although AGW crowd would disagree, it grows back.

    That all sounds great in theory, wcp2. But in practice, when a woman is walking five miles a day in search of a few sticks and twigs, fuel efficiency becomes hugely important.
    You should travel around the parts of Africa that have been nearly denuded of wood, and think about the picture. “Buy you a couple of meters of wood”? Sure … if there were wood around to buy. Your theory is the third world equivalent of “let them eat cake”.
    Finally, even poor folks understand the importance of running cost, and how it may be much more important than initial cost …
    w.

  73. jack morrow says:
    May 10, 2011 at 6:15 am

    I’m a big fan of Willis, but this is a crock. Several people have mentioned one problem and that is costs. Who will pay?

    People buy cookpots today. Why would they not buy a cookpot which hugely increases fuel efficiency? Sure, it will be out of the price range of some.
    But that is true of anything and has never been a reason to throw up our hands and declare something a “crock”.
    w.

  74. Methane from human and animal waste? Nope. Not enough methane made to be worthwhile. You do make enough to run a waste solids digester, but not enough to return it to a city. And there is a bunch of H2S you have to remove.

  75. Michael J. Dunn says:
    May 10, 2011 at 7:57 am

    Sadly, in today’s environment, casting a novel idea afloat on the internet may only provoke the unscrupulous to capture it and attempt to patent it, thereby creating the irony of a situation in which the actual creator could be legally prevented from using his own idea.

    No can do, and I’ve put the design out here specifically to prevent people from patenting it. To patent it they have to show that they thought of it first, that there is no “prior art” … and if it’s on the internet that’s gonna be real tough.
    w.

  76. Carl Brady says:
    May 10, 2011 at 8:01 am

    I was rather surprised that no one mentioned that LP gas would probably be better as a fuel. See one one LP gas company in India is doing to supply community LP gas kitchens for rural communities, http://www.exceptionalenergy.com/uploads/Ressources/WLPGA%20-%20community_kitchens.pdf.

    Indeed, and you should be able to use a cookpot like the one I drew above to improve the efficiency of your average stove.
    w.

  77. Tallbloke, awesome photos. I love the undying ingenuity of the human species.
    w.

  78. Might be wrong, but I believe this has been done in Vietnam for centuries and is used to cook dish called “Luo?”. Bowls of water/wine surrounding a central column containing rising heat from the source located in a ventilated pan at the bottom.
    Probably a derivative of the Chinese tech noted in an earlier post…
    =8-)

  79. I love this blog. Which would be more efficient- a thermette or a rocketstove? I am not familiar with thermettes and I know rocket stoves can vary based on insulation and materials used. But would anyone here have a rough idea?

  80. Michael J. Dunn wrote (snipped): “casting a novel idea afloat on the internet may only provoke the unscrupulous to capture it and attempt to patent it”
    My understanding of patent law (which could be written in five lines on a small piece of paper) is that things that are self-obvious or already known to the public can’t be patented. They have to be new and original to be patentable.
    IanM

  81. Russians will declare a samovar to be their “national heritage device,” and demand a huge royalty from anybody trying to sell anything resembling it.

  82. Better start handing these out in the UK. It will be thing folks can afford once the cost of wind power hits home.

  83. But that is true of anything and has never been a reason to throw up our hands and declare something a “crock”.
    If it were, would that make this a crock-pot? =)

  84. Thanks, Willis! I’ve long been a big fan of these simple, aluminum solar cookers;
    http://www.sunoven.com/about-us.php
    However, no sun = no heat! Problem solved. Your proposed scheme reminds me of an industrial steam-tube boiler with economizer for waste heat recovery (namely, soup/stew).
    Lesson: there is no “one size fits all” for these gadgets, and developing countries could use a mix of low-cost technologies. This will save resources & lives, as indoor pollution load from particulates (generated while burning kerosine, manure, wood etc.) is a huge problem for those folks. Keep up the good work!

  85. Another Gareth says:
    May 10, 2011 at 8:43 am
    John from CA said: “As gross as this sounds, why not use human waste to generate methane and use the methane for cooking?”
    A good idea. In Nepal, India and China and elsewhere human and animal waste is made into gobar gas.
    =========
    Thanks Another Gareth, very interesting read.

  86. In stead of the pot holder you have on top, make it a grill. You could still place a pot on it, but could also grill without the pot.

  87. Alexander Feht says:
    May 10, 2011 at 10:28 am
    Russians will declare a samovar to be their “national heritage device,” and demand a huge royalty from anybody trying to sell anything resembling it.
    =======
    Good point Alexander Feht,
    Here’s a modern example that’s very similar to Willis’s idea but its a design patent not a mechanical patent. The original idea is so old it isn’t patentable and design patents are only as good as your ability to protect them.
    http://www.manworksdesign.com/sam_eng.html

  88. Mike Bromley the Kurd says:
    May 10, 2011 at 2:49 am

    …while decoupling all that waste cash from the bottlomless money pit of CAGW and applying a fifth of it to providing clean water to put in the pot….

    If it’s cheap (in terms of energy) you can boil water, which protects your kids today from any germs, bacteria, or parasites in the water. Waiting for clean water to arrive takes time. I know it doesn’t solve some water problems (heavy metal content), but it’s a huge step.
    w.

  89. Lots of good work has been done by many people on cheap 3rd world cookstoves, most based on gasifying the wood to provide clean burning and high efficiency a google search on _top lit updraft gasifier stove_ will give you many interesting hits. I built a demo unit myself from two soup cans and some steel hardware cloth, with excellent results. Actually much simpler than your design, and more versatile, check it out.

  90. JohnL says:
    May 10, 2011 at 3:51 am

    BTW: If you have a gas water heater you can find the spiral fin design in the center flu. It’s a drop-in piece that slows the exhaust gas. It increases heat transfer, but also reduces the amount of carbon monoxide to near zero.

    Thanks, JohnL. That works. What I’m trying to do in addition to increasing heat transfer through existing surface area (as you rightly propose) is to increase the surface area. For this purpose spiral fins are better.
    As a thunderstorm man I’ve always been fascinated by vortices. I’ve made working Hilsch vortex tubes from the design in the magazine back when Scientific American was actually scientific.
    So I figure that I need to set up my own little fiery inverted tornado inside the magic cookpot. Put spiral fins in. Round off all of the corners. Set up the air intake to introduce air in a spiral direction. Make the shape of the funnel up the middle like a trumpet bell for the best coupling.
    The advantages to this method are
    • Longer contact time. The spiral path up the chimney is longer than a straight-up path.
    • Increased turbulence at the metal surface. The air will be better mixed near the metal.
    • Increased pressure at the metal surface. The centripetal force will press the air into close contact with the metal walls. This will increase the heat transfer rate.
    • Increased surface area. The fins will transfer their heat to the metal container and thus to the water.
    I haven’t drawn it up yet. I’ll post it when I do.
    w.

  91. Also, TLUD gasifiers overlap strongly with biochar, which puts crop waste to good use while improving clayey and sandy soils. The AGW folks ought to love biochar because it can sequester carbon _as carbon_ for thousands of years, but somehow saving the world from that debbil CO2 *without* requiring massive government intervention doesn’t seem to appeal to the usual suspects.
    It’s hard not to become more cynical when cost effective, positive value solutions are downplayed in favor of taxes and cap-and-trade schemes. It’s just too damn hard to skim off enough graft from a hundred million small biochar operations.

  92. I designed and build an solar oven, it works great. I did a 4lb tri-tip roast in it in about 4 hours in the Sierra Nevada summer sun. I had to move it twice or so because there are a lot of tall trees around.
    It ought to work well in a place like Tanzania.

  93. Willis Eschenbach says:
    May 10, 2011 at 9:32 am
    Tallbloke, awesome photos. I love the undying ingenuity of the human species.

    A Brit’s desire for a truly fresh cup of tea is the mother of invention.
    Cheers. 🙂

  94. 2Hotel9 says:
    May 10, 2011 at 8:28 am
    Tall Bloke, my brother from another mother!!! I have made camp stoves using various sizes of metal coffee and soup/food cans, for use with wood, charcoal, trioxine tabs and even candles. Have made candle lanterns from beer cans, one from a Fosters can that we used for several years.

    Cheers to you too. I love tinkering with lightweight metal materials. One design I have in progress uses some high tech. It’s a woodstove with three peltiers on the side which drive a motor and fan. The heat from the stove generates electricity via the peltiers. The fan cools the peltiers and a duct forces the warm exhaust into the base of the stove for enhanced heating rates.
    The tricky bit I’m trying to perfect is a titanium strip which deforms at the correct temperature to shut off the forced air supply before the soldered joints in the peltiers melt…

  95. A few ideas:
    Nice idea – it isn’t new, but it is innovative.
    1. The lid needs handles.
    2. If the lid was one piece you could add a hook to one of the pot handles to hang the lid on. This would keep dirt off the lid while stirring whatever is in the pot.
    3. Make the base separate from the pot so the pot can easily be removed and put back without disturbing the fire.

  96. Genghis says:
    May 10, 2011 at 8:02 am
    I love the comments and the idea, but the 800 pound gorilla that I see in the room is that the central heating idea makes it very hard to clean and cook anything in the water.
    It will work great for boiling water for tea, and noodles but that is about it. A pot is much more efficient to actually cook in and clean.

    Using the KISS principle, how about just using a pot like an angle food cake pan with the central chimney on the three rock system. Accessible to put stuff in the hot water, more surface area to transfer heat, already available in mass production, just not available in the areas of the world that need a more efficient stove/pot.
    If you were custom designing such a pot, replace the conventional conical chimney with a hyperbolic chimney as used in cooling towers to produce a better draft, and add a central swirl insert to lengthen the residence time of the hot gases, and if bonded to the walls of the chimney, act as fins to increase heat conduction.
    Add a small fitted lid like a dutch oven and you have an easy to clean pot that has multiple uses, the top could be used to increase heat by putting hot coals on the top like dutch oven or could be used as a food warmer from the steam produced by the boiling water.
    Teach the users to make a clay outer jacket the pot fits in for insulation and you have additional heating surface and ducted exhaust around the outside surface too.
    Larry

  97. Nice refinement of the Thermette Willis. Brought back many memories of camping alongside the NZ South Island Alpine rivers.

  98. Willis Eschenbach says:
    May 10, 2011 at 12:03 pm
    • Longer contact time. The spiral path up the chimney is longer than a straight-up path.
    • Increased turbulence at the metal surface. The air will be better mixed near the metal.
    • Increased pressure at the metal surface. The centripetal force will press the air into close contact with the metal walls. This will increase the heat transfer rate.
    • Increased surface area. The fins will transfer their heat to the metal container and thus to the water.

    I fold my energy drink can chimneys with a concertina of ridges. This increases surface area and provides the taper which increases gas velocity near the top where the exhaust gases have cooled and contracted. a separate spiral hanging in the chimney like in a gas flue isn’t such a great idea because the heat can’t be transferred to the liquid. Making the chimney out of material as thin as possible and with as high a heat coefficient as possible helps rapid energy transfer. Aluminium is good. Copper is even better, but heavy and weak.
    The spiraling intake idea is already in use on the 4 dog titanium woodstove.
    http://www.fourdog.com/

  99. Build a slightly bigger “Dakota-hole” fire pit with 3 stones (or bricks) in the bottom.
    A conventional pot fits down the hole and sits on the stones with 1 or 2 inches of clearance, so it is heated on the bottom and the sides at the same time.
    Efficiency would rate with the best.
    A steel mesh can be placed over the top to warm your buns, grill the steaks, heat your coffee, dry your laundry, etc.
    Feed the fire from the hole with long chop sticks, or from the top by removing the pot.
    “Fail-Safe” Uranium fuel-electricity is so much cleaner and easier…
    these ideas are so stone age… sigh.

  100. re Willis

    Thanks, JohnL. That works. What I’m trying to do in addition to increasing heat transfer through existing surface area (as you rightly propose) is to increase the surface area. For this purpose spiral fins are better.

    But potentially harder to clean, especially if fuels are dirty. Think hexamine gunk and having a simple design that can be cleaned with a handfull of sand.
    Or.. what about combining with the Multimachine initiative wsbriggs mentioned earlier to make a better version of this-
    http://www.brad.ac.uk/archsci/depart/resgrp/amrg/Rievaulx02/Rievaulx.htm
    similar principles seem like they could be used to make low costs smelters to turn scrap into cookpots?

  101. There are a couple more refinements IMNSHO.
    A ‘straight-through’ air intake is a problem in windy areas, the water is still going to convect a decent amount of heat to the outer wall, and the placement of an actual pot on top has room for improvement.
    The link at the end of this paragraph doesn’t have all of your improvements – but several of the ones they do have are easy – and not overwhelming pricewise – additions to yours.
    http://darfurstoves.org/our-solution/science/
    Note that the entire thing has a ‘double wall’. The base of the wall has cutouts for fresh air, but I’m not certain you need them – the ‘chimney’ is well away from the ‘inlet’ even if the outer wall was a simple straight cylinder with notches for the handles. The intervening space then becomes a pre-heater for the air and makes for -very- little convection from inner-to-outer wall as the air is actually flowing into the combustion chamber. The ‘outer wall’ is completely non-load-bearing, and can be whatever can stand up to the local winds.
    A second thing they’ve done is shape the heater’s exhaust around the pot itself. They can do this because they’ve standardized on a specific pot. But with your ‘X on the chimney’ design, there could be different inserts for different pots. A basic ‘outer pot with hole in center and crosspiece to support inner pot’ retains that much more of the heat.
    Considering making one out of a $10-20 aluminum bundt pan:
    http://www.amazon.com/MIRRO-Aluminum-Bundt-Cake-Baking/dp/B003AYHX58/ref=sr_1_6?ie=UTF8&qid=1305057376&sr=8-6

  102. Smokey says:
    May 10, 2011 at 12:28 pm
    tallbloke,
    Maybe this is what you’re looking for.
    ===========
    Thanks Smokey,
    So much for the link I provided earlier related to the hydrogen car conversion. Found this from your site link related to muscle wire.
    http://www.switch2hydrogen.com/h2scams.htm

  103. There are some very ingenious solutions in use ranging from pottery and metal cans to wrapping wood sticks in aluminum foil. Use a search engine with the search term “wood gas stove” or “wood gas stove” and “Africa” The same searches on YouTube bring up some good videos. See the YouTube videos featuring “wood gas stove” and “aluminum” or “aluminum foil”. Here are a couple of links:

    http://e-woodgasstove.blogspot.com/2006/06/woodgas-stoves-made-with-potters-clay.html

  104. Smokey says:
    May 10, 2011 at 12:28 pm
    tallbloke,
    Maybe this is what you’re looking for.

    Thanks Smokey, I’ve been messing about with the arm off my busted titanium specs frame. 🙂

  105. clipe says:
    May 10, 2011 at 2:04 pm
    Is there a practical way to produce electricity from a pot?

    From your link:
    http://www.alternative-energy-news.info/waste-heat-to-electricity/
    This was one of those content free press releases I find so dissatisfying.
    “Thermoelectric devices designed by Bergfield and Stafford can generate power that can lit a 100 Watt bulb or increase car’s efficiency by 25%.”
    Yeah? Cool. How much does it weigh and how much heat is required?? It only exists as a computer simulation, but just supposing it really can increase a car’s efficiency by 25%, let’s think how much power they are claiming to convert and how efficient the process would have to be.
    Cars are pretty inefficient to start with, so improving that situation by 25% might not be all that exciting. Added to which a good percentage of the waste heat is normally used to keep the car’s occupants warm on cold days, leaving less for conversion into electricity.
    The current best solid state thermoelectric generators cost a lot for small returns. I’ll await developments with some resignation.

  106. I’m no engineer, but looking at figure 4, the cross section, it looks like the shape of the firebox might be optimised a bit – maybe made into a shape that’s a section of a sphere so it would naturally concentrate the heat of the fire into the centre of the firebox. Of course you’d have to then have some holes in that sphere section, probably with sliding covers so that you could control and optimise the volume of air flow through the firebox and perhaps add additional fuel to a flagging fire.
    Granted it would increase the complexity of any casting, provided you were contemplating manufacturing this as a cast piece…

  107. I love this!! And you have published it to the world meaning that it can’t possibly be patented. Now anyone can make this and help the world instead of one greedy person getting all the money.

  108. Let’s not forget the immortal Trangia stove. Weighs nothing, works outside in a storm, no moving parts, runs on alcohol. I’ve used my two for over thirty years. They don’t wear out, and I can simmer as well as boil. Top converts to a frying pan!
    I wonder if a sturdier household version wouldn’t help in poor and remote areas. If we can run Prince Charles’ Aston Martin on alcohol, we should be able to cook rice with the stuff.

  109. kbray in California says:
    May 10, 2011 at 12:41 pm

    … “Fail-Safe” Uranium fuel-electricity is so much cleaner and easier…
    these ideas are so stone age… sigh.

    I agree, but there is such a thing as “appropriate technology”. As I said above, you can wait for the gummint to bring you clean water and cheap cooking technology … or you can roll your own.
    w.

  110. Willis Eschenbach says:
    May 10, 2011 at 3:50 pm
    you can wait for the gummint to bring you clean water and cheap cooking technology … or you can roll your own.

    Quite right. And speaking of which:
    http://greensteamengine.com
    Ubercool 70% efficiency with the recondensing and distilling rig too.

  111. Heat transfer fins. Into the fire box {flame path} protruding from the fire box directly into the water. Force the heat to spiral upward. The stew pan needs vertical heat transfer fins into the stew, and vertical heat transfer fins into the flame {heat path}.

  112. Dont know if anyone picked up on this !! In your bottom pot section, you need to have 2 x removable pots (shaped in a 1/2 donut shape each) that fit in and are removable. You cant cook inside the actual heating unit iteself because cleaning this thing will be too hard, so you have to have insertable pots that fit inside.

  113. Hi Willis
    Like many here, I have used the Thermette for years – available in two models – one tin the other copper.
    My copper one is very thin-walled, so every now and then it gets a huge dent in it that drastically reduces the water capacity – but I discovered that compressed-air reshapes it nicely.
    Tragically though, the Thermette has soldered joints – it’s not the first time – and I’m sure it won’t be the last when I’ve let it boil dry and had to spend hours gently resoldering
    How do you propose to make your device waterproof and free of such problems?
    Andy

  114. Hey Tallbloke, great photos.
    I’ve built several alcohol stoves, and a couple of wood stoves – but I never tried one of these. Do you have build instructions of your stove, or just the photos?
    Thanks for the ideas!

  115. Willis, keep the original design. The mods might be on the base to reverse the flange out for stability and possibly making manufacturing a little easier. Cast Iron might be the material of choice as it has proven to stand up to the rigors of being cookware. And instead of a fancy radiator to maximize the heat area, turn groves inside and outside of the chimney with would increase the surface area.
    And the benefit of cast iron is that all the thermite junkies could fix their broken Willis’ with it. 😀

  116. In our home, we have a middle aged, attractive lady to make cold food and liquid warmer. How she does it is her business, but she is very good at it. She is also more shapely than a chip heater and does not smoke. We have not had to think about this before, but I think we would call it “civilisation”.
    There was a time in history when all countries had about the same degree of civilisation. The differences we see now are a direct consequence of political decisions including warfare.
    If funds are to be expended, they would best go into showing individuals everywhere the ideals of self-respect, self-sufficiency, altruism, pride in self-advancement. We won’t get there by taking farming land to grow potions to power motor cars.

  117. Martin Hale says:
    May 10, 2011 at 3:10 pm

    I’m no engineer, but looking at figure 4, the cross section, it looks like the shape of the firebox might be optimised a bit – maybe made into a shape that’s a section of a sphere so it would naturally concentrate the heat of the fire into the centre of the firebox. Of course you’d have to then have some holes in that sphere section, probably with sliding covers so that you could control and optimise the volume of air flow through the firebox and perhaps add additional fuel to a flagging fire.
    Granted it would increase the complexity of any casting, provided you were contemplating manufacturing this as a cast piece…

    Agreed. This is a first crude unit. Further refinements will occur.
    I’ve never considered anything but cast iron for this. If it’s made out of thin metal it’ll burn through and be harder to make. The cookpot should be castable as a single piece, although you might want to separate out a firebox that you could lift the pot off of the firebox. Complexity of the casting (within reason) doesn’t increase cost beyond the increased cost of mold-making.
    w.

  118. Jarryd Beck says:
    May 10, 2011 at 3:42 pm

    I love this!! And you have published it to the world meaning that it can’t possibly be patented. Now anyone can make this and help the world instead of one greedy person getting all the money.

    You got the plan exactly. Now it just needs someone who is sandcasting and making cast iron cookpots to modify their design slightly …
    w.

  119. AndiC says:
    May 10, 2011 at 5:49 pm

    Tragically though, the Thermette has soldered joints – it’s not the first time – and I’m sure it won’t be the last when I’ve let it boil dry and had to spend hours gently resoldering
    How do you propose to make your device waterproof and free of such problems?
    Andy

    Cast iron … so it’s just like a cast iron stove, doesn’t need to have water in it.
    w.

  120. http://www.trangia.se/english/
    I neglected to post a link before. I’d love to buy a new Trangia but the old ones won’t wear out, and there’s nothing to break or malfunction if you are using alcohol. I have the Trangia Mini for indoors and in-tent, the storm-cooker for outside. I’ve faced the storm-cooker into high wind and rain and it actually boils better than with no wind. Why not engineer a larger, more solid version? I’d love to own one for domestic purposes when there are blackouts and picnics. Of course, Willis’ idea is a great one, and the storm-cookers vent system may be encumbered by patents.
    That said, it’s so utterly simple, patents may not restrict much.

  121. As mentioned above, these kettles use the same design as typical gas fired water heaters (or maybe it’s vice versa).
    I would not think that cast iron would be a suitable material to use. The secret to heating the water quickly is the quick transfer of heat through the sheet metal. Cast iron has more mass, requiring more btus of energy in order to heat it before it begins heating the water. Additionally, the thickness (mass) of the cast iron will result in higher temperatures of the cast iron inside the flue, which will further reduce thermal transfer efficiency.
    In other words, I would stick with the sheet metal versions, perhaps with the addition of an exterior insulating barrier of some sort.

  122. AndiC says: “…Tragically though, the Thermette has soldered joints – it’s not the first time – and I’m sure it won’t be the last when I’ve let it boil dry and had to spend hours gently resoldering.”
    Uh, don’t you mean brazed? I hope you’re not using solder in any wetted joints. Lead, and all that.

  123. Too much good stuff here to comment on all of it. I’ll just cite Tallbloke, Hultquist, Shanghai Dan, and John Johnston, in addition to Willis, for their fascinating comments. There are others, but I haven’t time to list them all.
    One negative aspect: A friend of mine who was employed by a global do-gooder organization worked on a device intended for use in third-world countries where the poverty level made lives short and miserable. It would have helped hundreds of thousands. The project was a failure–not for engineering reasons, but for economic reasons: the level of bribery necessary to import such devices made it impractical to proceed. It must never be assumed that “redistributing wealth” and throwing money at undeveloped countries will improve the lives of their citizens. Graft is a bottomless pit.

  124. One more comment:
    (1) I agree that cast iron is the best material. It’s durable, a better heat conductor than stainless steel, and cheap, plus it holds heat well for nighttime heating, where needed.
    (2) Avoid hard-to-clean fins or other accessories. Make any spiral internals removable and easily replaceable.
    (3) Avoid nesting parts in the heat conduction path, unless they are really necessary and carefully designed. Any air gap will impede heat conduction significantly. If the gap is wet, steam may form, with consequent bumping problems.
    (4) Consider developing a mantle holder that clips onto the top of the chimney, as in a kerosene lantern. This could provide light at night, if made strong enough to permit removal and handling, or cheap enough for frequent replacement.
    (5) Consider allowance for embedded cast-in serial numbers to reduce theft.
    (6) Stick to one piece construction, if possible, also for anti-theft purposes.
    (7) An alternative project would be a reusable, fast-release mold for local manufacture of ceramic cookers at reduced cost. Be aware, however, that the collapse of an unreinforced ceramic chimney or firebox could be dangerous.
    (8) Don’t use any overseas manufacturer that has a habit of putting lead in its alloys or ceramic products, or melamine in its milk.
    Doug: got any pictures?

  125. An interesting source of ideas here. I have been considering a similar problem for boat heating because it seems that to buy anything “off-the shelf” I have to spend more than I paid for the boat! I had considered putting an inexpensive parafin (kerosine) greenhouse heater inside something like a kelly kettle vented through a chimmney in the cabin roof. The chimney was formed around a copper or aluminium archimedes screw in good contact with the thin copper chimney to increase the effeciency of what is in effect a heat exchanger/chimney combination. Add in a pressure relief valve and a small 12V in line pump on a radiator loop taking the hot water around the boat and hey presto! We have an inexpensive boat heating system. Adding in a samovar tap and we have hot water on demand! Seems there is a first world business opportunity here also.
    eco-geek

  126. Ron Dean says:
    May 10, 2011 at 6:06 pm
    Hey Tallbloke, great photos.
    I’ve built several alcohol stoves, and a couple of wood stoves – but I never tried one of these. Do you have build instructions of your stove, or just the photos?
    Thanks for the ideas!

    Hi Ron,
    I haven’t written up instructions for constructing the ultralight kettles I make. One day I’ll make the time. Basically, the trick for the small one relies on the fact that the diameter of the body of an energy drink can is the same as the diameter of the neck of a standard size beer can. So if you cut the inside edge of the lid of the beer can out, you can fit the energy drink can to it and roll/press the flange left by the removed lid to make it watertight. It’s tricky, the failure rate is high, and it requires patience and dexterity. I did a four year engineering craft apprenticeship as a teenager.
    Some people just epoxy it in place, but I make no recommendation about that, as some others don’t like the idea of the epoxy being in contact with the water you drink. Annealing the aluminium near the joint first helps. The completed kettle weighs 30 grams.
    It takes a good deal of experimenting to get the vapourisation rate of the mini penny stove right for an efficient burn too, and this varies according to the altitude you use the stove at, and the ambient temperature. I’m still working on perfecting an adjustable stove, but I found a neat way to get a limited range of adjustability. I drill the jet holes in a pattern such that by changing the rotational orientation of the kettle relative to the stove, the proximity of the folded chimney flutes to the flame jets affects the amount of heat reflected back onto the stove. I make the stoves out of 40mm diameter lip balm pots. They weigh 4 grams complete. The priming ring is press fitted after cutting from the bottom edge of the energy drink can.
    Nothing goes to waste. 🙂

  127. The other big advantage of using the central chimney design is that you can extend a removeable chimney through the hut roof. The health hazards of cooking over charcoal indoors are alleviated. It increases the health hazard of setting fire to the roof though, a mesh spark arrester is recommended.

  128. For those of you who don’t think a change in how you cook can greatly change a landscape, I suggest you check out before-and-after pictures of certain parts of India, where over-grazed and denuded hills have been successfully reforested.
    I visited the area around Amednager in 1974, and again in 2000, and the change was striking. A harsh and desert-like landscape was softened by the tops of many young trees. There did not seem to be fewer goats, (which got the blame for denuding the landscape in the old days,) but there did seem to be less smoke from cooking fires.
    In 1974 cooking seemed largely done, away from the city, by fires of twigs and dried dung. In 2000 propane was much more widely used. Trucks delivering many, small, individual tanks were a common sight on the rural highways.
    Effort was needed, when it came to planting all the trees. It was also important to educate the young boys who herd the goats not to climb trees and rip down branches for their goats. However I think the introduction of propane greatly reduced the stress on the environment. In essence the desert bloomed.
    Here’s a different example of how a changed economy can dramatically alter a landscape:
    In New Hampshire the landscape was 90% treeless in 1900, and hay was a great export, for horsepower in the cities to the south was dependant on imported hay. The change to cars and gasoline resulted in hay becoming less valuable, and New Hampshire is now 90% forested.

  129. Why not just wrap the meal in aluminium foil and wire it to the overheated gearbox of the nearest windmill, of which there will be millions if some people have their way. Or, if you fear ladders, wire it to the focus of a solar parabolic, of which there will be millions if some people have their way.

  130. Geoff Sherrington says:
    May 10, 2011 at 6:56 pm
    In our home, we have a middle aged, attractive lady to make cold food and liquid warmer. How she does it is her business, but she is very good at it. She is also more shapely than a chip heater and does not smoke. We have not had to think about this before, but I think we would call it “civilisation”.
    —————————————————–
    Geoff, your comments are usually worth reading, but this kind of ‘all boys together’ crap is not worthy. As someone said, I fear that we do not see you at your best.
    What is interesting about this thread is that it is clear that many devices not unlike that suggested by Willis have been around for a long time. The real question is – why have they not been utilised? When billions of dollars a year are being spent in international aid, how come the existing devices, tried and tested, like the New Zealand ‘thermette’ are not already out there?
    ‘Invented’ things to save the world are a dime a dozen. The hard questions are about implementation. In the case of cooking, the low status of women in many Third World cultures might be a reason. Another might be the priorities of donors, who prefer things they can point to and be photographed with. Perhaps the ‘thermette’ does not work in those environments – who knows?
    While it has been fun and interesting to read this thread, there is no doubt that chronic poverty is not solved or even ameliorated by building a better mousetrap.

  131. johanna says:
    May 11, 2011 at 9:39 am
    Geoff Sherrington says:
    May 10, 2011 at 6:56 pm
    Winston Churchill and Lady Astor.

  132. Classy, Caleb.
    Did you think I would not understand the reference?
    For those who missed it, he is saying that I am ugly, and that he will be sober in the morning. It is quite possible that one of those statements is true.
    Not really in keeping with WUWT manners.

  133. johanna says:
    May 11, 2011 at 9:39 am

    … While it has been fun and interesting to read this thread, there is no doubt that chronic poverty is not solved or even ameliorated by building a better mousetrap.

    Say what? Better mousetraps, in hundreds of different ways from better stoves to inexpensive modern clothing to vaccinations to cheaper communications, have been of great use to ameliorating the lot of the poor of the planet.Your claim is not only meaningless, it is totally wrong and an insult to those who have worked in the field.
    Go ask a woman who now has some kind of improved stove if she would go back to the old one before you start this kind of nonsense. Go ask a man with a flashlight why he doesn’t use a burning reed torch, and if he’d go back to it.
    I love you armchair experts, you’re likely great folks and you have great fantasies … but all I can say is, go out and learn something in the field before you write about your fantasies, people like you are dangerous when you start claiming those fantasies are real.
    w.

  134. W.
    you should look at the various wood-gas camp stoves on the market … they are able to burn alot of the low volume fuel (twigs, etc) available in the 3rd world and can burn the fuel down to ash … i.e. very efficient …
    some of them do require batteries but many designs require nothing but fuel …
    I’ve experimented with a small (less than 4 inches across) homemade version and have been able to create smokeless blue flames at the top of my mini stove that can heat up a pot of water very quickly …
    the basic concept is that they seperate the generation of burnable gases and the actual burning of the gas … in other words the bottom of the stove “cooks” the fuel in a low oxygen environment, generating very hot burnable gas which rises to the top where it is mixes with clean air that “ignites” the gases … they cook the fuel down to ash in the process …
    the typical campfire tries to generate the burnable gases and burn them with the same air and location which leads to left over fuel in the form of charcoal and unburned fuel which escapes as gases before burning …

  135. Willis, your assumption that I am an ‘armchair expert’ is not only unfounded (you don’t know me), it is incorrect.
    “go out and learn something in the field before you write about your fantasies, people like you are dangerous when you start claiming those fantasies are real.”
    What fantasies? Please explain.
    You said:
    “Go ask a woman who now has some kind of improved stove if she would go back to the old one before you start this kind of nonsense. Go ask a man with a flashlight why he doesn’t use a burning reed torch, and if he’d go back to it.”
    Please reference where anyone in this thread (let alone me) suggested anything of the kind. Who are you railing against? What kind of nonsense? Since you linked it to my post, I would appreciate your explanation of the colorful phrases about burning reeds and torches, in particular.
    As we say in Australia, you’ve lost it, mate.

  136. Willis, you nail it, right out of the park. The “better mouse trap” analogy is precisely what has raised humans form grubbing around in the dirt. BooYaa, Brother Man! BooYaa.

  137. you guys are really missing the boat.
    as the white haired gentleman who had been writing camping columns in “Guns & Ammo” said about thirty years ago when asked to divulge what the greatest camping
    gadget invented in the last century was????
    “My Airstream trailer” no doubt about it.
    C

  138. Johanna,
    You wrote,”…there is no doubt that chronic poverty is not solved or even ameliorated by building a better mousetrap.” Then you would solve or ameliorate chronic poverty, how?
    Writing as only slightly more than an armchair quarterback, I agree that implementation(marketing) of an invention is a hard question. The Patent offices are filled with good ideas that never caught on, and we are forced to choose between often mediocre products because of superior marketing and market manipulation (Microsoft comes to mind). The world is also littered, quite literally, with the cast offs of usually well intentioned development and aid projects, much like the heavily subsidized wind and solar farms that are being rammed down our throats.
    The customer needs to want the product and it needs to make economic sense or it will fail. If it needs a subsidy, it doesn’t make economic sense. Poor shouldn’t imply absence of income, intelligence, pride or dignity. If a given product passes a poor consumer’s cost benefit analysis, a way will be found to pay for it.
    In the case of cooking stoves, there are dozens of possible solutions for any given situation, but the successful solution will meet the local buyer’s requirements. Many successful implementations of improved cooking stoves have been local adaptations of good designs, variations of the “rocket stove” and TLUD gasifying stoves being well represented.
    Kerosene and Propane stoves have seen much more widespread acceptance, though the fuel is often subsidized (heaven help anything combustible when the subsidies are dropped. Weren’t some people burning their books to stay warm in England when the electricity failed or they could no longer pay for it?). I will give a shameless plug for solid wax as a fuel — safe, non-toxic, easy to transport and store.
    An improved cook stove in every household may not solve chronic poverty, but I am convinced that it can ameliorate some of its symptoms, so it is certainly worth some effort, but there are probably more appropriate places for carrying on the discussion than WUWT.

  139. I’m thinking a small metal grate at the bottom for greater oxygenation of the fire/coals and finning on the chimney inside to improve thermal efficiency via greater surface area. Good idea.

  140. Jeff Carlson says:
    May 11, 2011 at 11:35 am

    W.
    you should look at the various wood-gas camp stoves on the market … they are able to burn alot of the low volume fuel (twigs, etc) available in the 3rd world and can burn the fuel down to ash … i.e. very efficient …
    some of them do require batteries but many designs require nothing but fuel …
    I’ve experimented with a small (less than 4 inches across) homemade version and have been able to create smokeless blue flames at the top of my mini stove that can heat up a pot of water very quickly …
    the basic concept is that they seperate the generation of burnable gases and the actual burning of the gas … in other words the bottom of the stove “cooks” the fuel in a low oxygen environment, generating very hot burnable gas which rises to the top where it is mixes with clean air that “ignites” the gases … they cook the fuel down to ash in the process …
    the typical campfire tries to generate the burnable gases and burn them with the same air and location which leads to left over fuel in the form of charcoal and unburned fuel which escapes as gases before burning …

    Thanks, Jeff. The gasification of wood was used in WWII by the Germans as a way to power trucks. They used that process because (obviously) wood doesn’t fit well into the cylinders of an internal combustion engine.
    However, while gasification provides energy in a different form, I’m unaware of any study showing that gasifying wood provides more energy than you can get by simply burning the wood. If anyone is aware of any, I’d love to see it.
    Finally, the cookpot I’ve shown above can be used with any fuel—wood, propane, wood gas, natural gas. It’s just an efficient way to transfer heat from hot gases to a pot.
    w.

  141. johanna says:
    May 11, 2011 at 1:09 pm

    Willis, your assumption that I am an ‘armchair expert’ is not only unfounded (you don’t know me), it is incorrect.

    “go out and learn something in the field before you write about your fantasies, people like you are dangerous when you start claiming those fantasies are real.”

    What fantasies? Please explain.

    Johanna, you claimed that technical progress was of absolutely no use to the poor. Your words were:

    … there is no doubt that chronic poverty is not solved or even ameliorated by building a better mousetrap.

    Chronic poverty can certainly be ameliorated by technical innovations (your “better mousetrap”). The number of examples is large. I gave some in my reply.
    So … in answer to your question, your fantasy is that chronic poverty is not ameliorated by technological advances. That’s what makes you an armchair expert, no matter how much time you’ve spent in the field.
    If you don’t see that the lives of the poor have been greatly improved by a host of “better mousetraps”, innovations in a variety of fields from medicine to energy over the last three hundred years, you’ve “had the experience, but missed the meaning”, as T. S. Eliot remarked.
    w.

  142. johanna says:
    May 11, 2011 at 10:57 am
    “Did you think I would not understand the reference?”
    Actually I didn’t think you would misunderstand, but apparently you did misunderstand.
    I was not referring to any specific quote, but rather the relationship.
    The specific quote that springs to my mind, when thinking of those two, goes like this:
    Lady Astor: Winston, if you were my husband I’d poison you.
    Winston: Lady Astor, if you were my wife I would drink it.
    I think the quote you were referring to went:
    Lady Astor: Winston! You are drunk!
    Winston: Yes, and you are ugly, but in the morning I shall be sober.
    There were others, for when those two got together the sparks flew. Lady Astor could drive Churchill wild. For example, she travelled to Russia and on her return she spoke glowingly of all the good things communism was doing. Churchhill knew about the famine she wasn’t shown.
    When sparks flew between them other people hushed, and watched, because it was apparently good fun. Despite the fact they were miles apart, politically, and quite rude to each other, they apparently liked each other. There was no false-front smiling and back-stabbing later. Each was bluntly honest, and appreciated honesty. When they conversed people shut up, because they said things “one simply doesn’t say in public.”
    That was what I was referring to, when I commented on the exchange between you and Geoff.
    I’m sorry if you thought I was saying you were ugly. That was not my intent.

  143. Willis,
    You said, “I’m unaware of any study showing that gasifying wood provides more energy than you can get by simply burning the wood. If anyone is aware of any, I’d love to see it.” I don’t have the references at my fingertips, but IIRC, the gasifying stoves get more heat out of the wood by burning flue gases that are normally wasted. That is not to say that other stove designs cannot be as efficient, but there are not very many.
    Proponents of gasifying stoves will also state that their stoves can cook the same amount of food as conventional wood burners for the same, or less, amount of wood, and leave the user char which can be used for other purposes, including, dare I say it, carbon trading, if the char is buried.
    Another positive of gasifying stoves is their ability to successfully utilize unconventional bio-fuels, such as rice husks and other agricultural waste.
    You brought up an important point when you wrote, “It’s just an efficient way to transfer heat from hot gases to a pot.” Heat transfer is at least as important as efficient combustion in reducing fuel consumption. The addition of a pot skirt to a three-stone fire may reduce fuel consumption as much as some improved stoves, though perhaps not as consistently. Separating designs for heat transfer from combustion give the cooking stove designer more flexibility in meeting local requirements.
    Using a Hay box (poor man’s crock-pot?) in place of simmering can also reduce consumption significantly.
    Please go to http://www.bioenergylists.org to find reports and documentation on gasifying stoves and many, many other designs. You may enjoy reviewing Micheal Trevor’s work on Majuro in the Marshall Islands. http://www.bioenergylists.org/en/taxonomy/term/1155

  144. Roger Carr says: May 10, 2011 at 3:38 am
    We put rubber tubes into the ‘wood chip water heater’ [modified gas cylinders] for 5 years while the Centre for Appropriate Technology sent the same design for use all over the desert communities of NT/SA/WA.
    Hot water in 10 minutes.
    The ironic thing was that SANTOS was to our south! And Mereenie fields to the NE. http://www.santos.com/exploration-acreage/production-processing/mereenie.aspx
    Our solution saved taking the Toyota out and pushing down mulga with the bull bar to cart back to the community. That was hard work on a cold night, such are desert nights. Aerial photography of the communities will [perhaps] show the dust bowl effect due to loss of vegetation that occurred as women went (or begged those with vehicles) to get fuel for cooking and heating purposes.
    John Marshall says: May 10, 2011 at 3:03 am
    I think you are switched on!

  145. Johanna
    http://wattsupwiththat.com/2011/05/10/the-magic-cookpot/#comment-658100
    Correcto.
    The reason that many women DO NOT use these technologies is that they are in a vulnerable situation.
    Cooking for the family in the family home, with daughters and young children about is a sole female occupation.
    Observe any such situation.
    Is there a spear, long handled knife in the picture? A gun?
    or even better a long length of burning firewood? Or hot saucepan?
    No.
    No.
    No.
    Is there a number proportionally larger than is expected to prepare a simple meal? Yes
    Yes
    Yes
    Yes.
    Nice try fellas and much appreciated. But your examples are for the camping, nuclear types. The types that are educated, employed and don’t need to rape women and kids for their next land conquest. Or satisfaction.
    Go try wearing a frock and living and feeding your kids (and elderly parents) in a tribal village or refugee camp.
    You’d be better off designing for women that would serve both [real] hunting and protection purposes.

  146. Geoff Sherrington says: May 10, 2011 at 6:56 pm
    In our home, we have a middle aged, attractive lady to make cold food and liquid warmer. How she does it is her business, but she is very good at it. She is also more shapely than a chip heater and does not smoke. We have not had to think about this before, but I think we would call it “civilisation”.

    That is a very funny comment Geoff.
    I realised when reading ALL the links and videos on the ‘bidet’ blog the cognitive differences among the view of bloggers. http://wattsupwiththat.com/2011/04/23/new-mystery-appliance-is-the-antithesis-of-the-green-dream/
    For instance I was reading the comments and something didn’t seem quite right.
    It was then I realised that the ‘model’ in the picture that I thought after viewing the picture ‘crikey, that model with the remote is sure hot, good spotting there Anthony’ was in fact not the model being referred to in the post.
    C’est la vie.
    False positives?
    Anyway, an excellent post Willis, yet again. Thank you.
    In response to Phil’s Dad http://wattsupwiththat.com/2011/05/10/the-magic-cookpot/#comment-657140 and
    ws briggs http://wattsupwiththat.com/2011/05/10/the-magic-cookpot/#comment-657129
    Smoke also seems to serve a purpose of equality in ‘smell distribution’ in some environments.
    Realities are:
    – Unwashed bodies (including the numerous infants) due to various reasons;
    – Infections with a high detectable smell factor (granuloma inguinale, pseudomonas, http://www.pseudomonas.com/p_aerug.jsp trichomoniasis etc);
    – Food preparation in such closed/populated areas requires ammunition (wood missiles are generally retrievable). Cooking attracts scavengers (human and animal) into the near vicinity of the household (eg anyone reading NT News will have read of the campdogs pulling down and attacking humans), though h/hold pigs are shocking and as rightly pointed out
    – Smoke minimises mosquito loads.
    Interestingly electricity including the powering of running water may serve to reduce all these realities whilst cooking. Possibly a hugely boring and tedious daily task (s).
    A TV could also be plugged in to keep the little hordes in one spot and under watchful eye! As would a fan to mimic seasonal wind direction and serve as a crude damper as a replacement for physically moving the ‘kitchen’ with the seasons.
    While some will go on with endless discussion of cultural (voodoo) factors as to the cultural purpose of smoke, this is generally because maths and science was not taught (or actively eschewed for a variety of reasons) in these environments. The lexicology and use of the word ‘no’ (positive/negative) has in my experience proved useful.
    Many bloggers possibly enjoyed the spectacular sunsets of the tropics in the burning off season.
    Jenness Warin (Jessie)
    Dave Wendt (question on need for LED brightness on the bidet model). Assuming you are male, I suggest a few test runs (could try double blind randomised). The designers most likely factored this in when designing the model. 🙂

  147. Willis,
    Your posts I always read because you deal with real people, their lives and deliver good ideas.
    Here is an accurate account of ‘the rocket’ as we used to call it, which heated water.
    http://ramblingsdc.net/Firewood.html
    Note no women (or kids) in the blurb.
    Interestingly ‘the rocket’ was used in the general area where the Blue Streak Rocket (Woomera, South Australia) is situated. http://en.wikipedia.org/wiki/Blue_Streak_(missile)
    I would upload some photos of students learning to use laptop computers for the first time in their adult lives many years later in my remote work, but I haven’t learned how to upload as yet. The female students used to go back to their wood fires to prepare the evening meal and heating up 1/2 44 fuel drums to wash kids. The washing of kids in hot water (which only occurred for a short time) significantly decreased skin diseases.
    Then the women returned to study in the evening, where we powered up with a little sine-inverter generator to use computers, projector, fluoros, fans (keep mozzies at bay) etc.
    I was grateful to have a local leader (and some other men) support the inclusion of women being educated, fighting (nicely) over various matters as we did do at times!
    On consideration, I think the local leader had never had a woman tell him he had enough lovely wives and me being a fourth would just give him more headaches. Or something along those lines. He agreed with that observation in the end. So we happily called each other by name only, rather than having to be fitted into a kinship system. With all the exhausting factors of such a system.

  148. The best for Africa may be very simple, because:
    – needs to be low cost
    – needs to be light for portability (which works against durability I suppose), because many people there are nomadic by tribal nature or by forced displacement
    – needs to be easily manufactured locally (I guess cast iron using sand molds would be though not light, aluminum is castable but more expensive, similarly the pottery device someone described herein )
    – using empty food cans may help facilitate in some areas
    – with the lack of a justice system in so many places theft will be a problem
    with the lack of a justice system in so many places
    – it is also a bad environment for learning, though the people are keen (recall the US Olympic runner who was taught school by older boys in a refugee camp, sitting on the sand using it as slates, with one makeshift blackboard hanging on a tree).

  149. As for building a fire in a hole, don’t you need an air inlet at the base? Otherwise it sounds useful to contain the fire, but needs something to sit on top to support the container for cooking?
    But a solar device sounds useful in the dry country of Africa.
    However from the variety of designs noted in this thread it appears technology is not the holdback – see my comment about society in a previous post.

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