Rocket Stoves

December 6, 2010 5:47 PM

As winter rolls around, my thoughts turn to warming myself. And I can't think of a more efficient way to do it than with a rocket stove.

Dr. Larry Winiarski of the Aprovecho Institute discovered the principles and designed the first one in an attempt to reduce the developing worlds reliance upon wood. Rocket stoves can cook a meal using paper or weeds, instead of logs. Now they are being used around the world


But I don't need them to cook my food, I want them to warm my mass. (and replace my 1950's fireplace!) Luckily others are already ahead of me on that and rocket-stove-based mass-heaters are well developed and the technology is definitely do-it-yourself friendly.
They range from the simple to the more advanced to the amazing

posted by psycho-alchemy (28 comments total)

Wow, I did not know about these. Amazing how such a simple idea can create so many possibilities.
posted by localroger at 5:56 PM on December 6, 2010

Well, I finally have the technical vocabulary to explain the traditional Russian stove. "Thermal mass"!
posted by Nomyte at 5:57 PM on December 6, 2010

pro rocket stove since 2008!
posted by tarantula at 6:21 PM on December 6, 2010

pro rocket stove since 2008!

I liked them before they were hot.
posted by The White Hat at 6:27 PM on December 6, 2010 [9 favorites]

well that's quite a coincidence. I was looking at woodfired oven building books right now and came across rocket oven books for the first time in my life, all of five minutes ago!
posted by wilful at 6:32 PM on December 6, 2010

We used to get technicians in from the rural energy bureaux to teach people how to make these in the project I used to work on out in the sticks. People were generally pretty handy by dint of being subsistence farmers so maybe that doesn't speak to the ease of making one as a DIY job, but definitely not a great technical challenge.
They're great in just about every way, and in that bit of rural China especially for the women, who not only got to spend less time collecting the already sparse fuelwood, but also (as it says at the how-to link) were far less likely to suffer the health consequences of smoke inhalation.
posted by Abiezer at 6:41 PM on December 6, 2010 [2 favorites]

They were the subject of a very kind article in the New Yorker not long back.

The work they are doing is great; personally, I was most intrigued by the mention in that article of the super-efficient pizza oven they put together for the workshop. I've considered building a wood-fired pizza oven, so the idea of a modern efficient version caught my attention.
posted by Forktine at 6:56 PM on December 6, 2010

Oh hey! They have a manual on pizza ovens on their site -- I think I might have found my winter project.
posted by Forktine at 7:03 PM on December 6, 2010 [4 favorites]

I wish to complain. None of these stoves actually use rockets in their construction. (/comicbookguy)

But, seriously, great stuff. It's small, (relatively) easy changes like this that do so much more than any number of expensive, trendy, cause du jour campaigns. I will now go back to lusting after a pizza oven in the backyard, thanks to Forktine. :)
posted by ninazer0 at 7:16 PM on December 6, 2010 [2 favorites]

I wish the graphic linked above was actually readable.
posted by amethysts at 7:16 PM on December 6, 2010 [2 favorites]

Russian stove?, please, the Finns didn't kick their asses in WWII just to have their stove technology appropriated, they're called Finovens.
posted by 445supermag at 7:22 PM on December 6, 2010 [2 favorites]

amethysts - to enlarge, use View/Zoom or Ctrl + (just like in Photoshop)
It takes 4 or 5 clix to reach legibility, but it's there.
posted by hexatron at 7:32 PM on December 6, 2010

Oh hey! They have a manual on pizza ovens on their site -- I think I might have found my winter project.

Oh god, please don't make comments like this.

Mods: please delete this post before my SO starts reminding me of certain unwise promises that certain people may or may not have made...
posted by pompomtom at 7:47 PM on December 6, 2010 [1 favorite]

Love the idea, but is it just me or is the text in the image TINY!
posted by russmaxdesign at 7:56 PM on December 6, 2010

Mods: please delete this post before my SO starts reminding me of certain unwise promises that certain people may or may not have made...

mate, have I got a project for you...
posted by wilful at 7:59 PM on December 6, 2010

there's a "A4 printable image" link in the upper tight corner that goes to a larger version. text is still not that great, but it's legible.
posted by russm at 8:08 PM on December 6, 2010

I thought this whole thing was really cool, then I looked at the other pages attached to this. Mainly how to pick perfect coffee cherries. This was a little unsettling, rather then how to feed and protect your family, it reads like: How to be a better impoverished export crop worker.
posted by Felex at 8:37 PM on December 6, 2010

I thought this whole thing was really cool, then I looked at the other pages attached to this. Mainly how to pick perfect coffee cherries. This was a little unsettling, rather then how to feed and protect your family, it reads like: How to be a better impoverished export crop worker.

It's a lot easier to feed your family when your cash crop sells for more money than it is to feed them on bare-bones subsistence farming. Just like it's easier to feed them when your improved stove uses a fraction of the fuel that the old one did.

Mods: please delete this post before my SO starts reminding me of certain unwise promises that certain people may or may not have made...

If I promise to build you a stove, and you build one for me...
posted by Forktine at 9:12 PM on December 6, 2010 [2 favorites]

I'd make one, but I'm all out of anthill soil.
posted by Joakim Ziegler at 9:37 PM on December 6, 2010 [1 favorite]

I like the simple materials and construction in the instructions.

It seems like this is just a conventional stove, so it's efficient in comparison to an open fire, but not, for example, compared to a stove that uses secondary combustion. Or am I misunderstanding how it works?
posted by Pruitt-Igoe at 9:51 PM on December 6, 2010

It seems like this is just a conventional stove, so it's efficient in comparison to an open fire, but not, for example, compared to a stove that uses secondary combustion. Or am I misunderstanding how it works?

That's my understanding, but the idea behind rocket stoves is to burn the fuel as hot as possible to get as complete and thus efficient combustion as possible. Forced-draft wood-fired devices with secondary combustion (which are essentially just wood-gasification units) are very efficient these days, but they are in a whole other realm technologically.
posted by ssg at 10:35 PM on December 6, 2010

Efficient? A rocket stove? You have got to be shitting me.

You can tell if a furnace is efficient by the material used in the chimney. My large commercial propane furnace uses PVC pipe. If you climb on the room and hold you hand over the exhaust, it's about as warm as your breath, maybe less.

Or you could put on a heated jacket.
posted by ryanrs at 12:42 AM on December 7, 2010

Efficient? A rocket stove? You have got to be shitting me.

They're very efficient compared to an open fire or primitive stove designs. Obviously comparing them to carefully engineered and machined, computer controlled furnaces available to the wealthy world they're not much. I kind of doubt that you could build a commercial propane furnace (for which they don't have fuel anyway) with anthill soil.
posted by atrazine at 1:14 AM on December 7, 2010

I kind of doubt that you could build a commercial propane furnace (for which they don't have fuel anyway) with anthill soil.

You're right - I could not. The ants in my neighborhood are complete slackers when it comes to producing anthill soil.
posted by Kirth Gerson at 4:06 AM on December 7, 2010 [1 favorite]

Efficient? A rocket stove? You have got to be shitting me.

I think you're confusing the efficiency of heat transfer with the combustion efficiency. Of course, burning propane, your furnace is also likely to be combusting more efficently because that's easy with propane. It's not so easy when you're burning logs, paper and bits of waste biomass. A rocket stove is hugely more efficient than an open fire (which is appallingly inefficient), but as atrazine said - of course it isn't as efficient as (for instance) a good gasifying wood boiler, but you can't make those out of cow shit and they need some way of storing energy to make them practical.
posted by silence at 5:44 AM on December 7, 2010

The cob mass heater links are interesting, but I think what you're really looking for, psycho-alchemy, is DIY Masonry Heater.
posted by richyoung at 8:29 AM on December 7, 2010 [1 favorite]

There are cheap/makeshift stoves like the Avan Stove (scroll to the bottom and read up) that use secondary combustion without a blower. I doubt they work much better than a rocket stove, though.
posted by Pruitt-Igoe at 12:56 PM on December 7, 2010

They are not as efficient in the burning process as the gasifying wood boiler shown above. (It is difficult to beat 100%) But that sort of comparison is not completely fair. The wood boiler is reliant on electricity and that energy should be accounted for as well.

We could also examine lifetime energy expenditures for manufacturing and fuel in order to get a more clear picture.

But I will stick with a straight comparison. A rocket stove while running should have a fire that is burning at least 1800 degrees in the combustion chamber. This does allow for gasification of the wood and complete burning of the volatile gases, the temperature at the end of the exhaust run is typically between 80-100f. The emissions of a a masonry stove is comparable to an EPA Phase II rated wood or pellet stove and the rocket stove mass heater is a refinement of that concept that allows better draft and smaller fuel. Estimates put forward put a well designed rocket stove at between 75 and 90% efficient at transferring the fuel in the combustion chamber to usable heat. However a lot depends on the operator.
posted by psycho-alchemy at 3:10 PM on December 7, 2010