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Dave and Anke
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Sunday, January 29, 2012

HiLow Tech Stoves: Rocket and Holey Roket (sic)

Photo from Photosfan
In the third world, much of the cooking is done around open, wood fires. We shantyboaters, living as we do in a third world of our own, can benefit from recent innovations in stove technology. Their workings are high tech, but their construction is low tech (or appropriate, if you prefer).

One of the odd facts about wood fires is that, without efficient combustion, up to half the energy of wood goes up in smoke. This means twice as much wood need be gathered for a given amount of heat, leading to deforestation in many areas. Smoke is, of itself, toxic, and women and children (predominantly the ones doing the cooking), suffer heavily from emphysema and other lung conditions and cancers.

The Approvecho Center, with Dr. Larry Winiarski, developed the Rocket Stove to address these problems.

It is essentially an insulated, L-shaped combustion chamber. The horizontal portion accepts wood and air, the hard turns at the angled join provide efficient mixing, and the upright portion is the chimney. The combined effect is a very hot burn, both of the wood and the smoke. Remaining hot gasses emerge from the upright chimney under appreciable pressure.

There are many ways to adapt this concept, including cookstoves, thermal mass heaters, steam generators and so on. For inside use, they may be enclosed in a box and vented outboard.

Holey Roket Stove with Holey Bio-briquettes
One of the more intriguing variations is the Holey Roket Stove. Instead of wood fuel, this uses donut shaped bio-briquettes. These are DIY from slurried biomass (manure, paper, sawdust, peat, weeds, etc.), formed and baked right on the stove. In areas where wood is scarce or protected, bio-briquettes offer a wide range of options for scroungers.

Of course, they needn't be mutually exclusive... with good design, a Holey Roket could burn either wood or Holey briquettes.

StoveTec is offering ready made (outdoor) rocket stoves in a roughly 5-gallon pail format for quite reasonable prices. These would make great deck or 'patio' cookers. You may also purchase stoves for Third World families at very low cost.

So look this stuff over. See how it can be worked in to your situation. The technology is highly scalable and versatile. Chances are, some variation will enhance your life.

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  1. Grover makes a nice camp rocket that seems a bit more efficient (their "heavy duty", square model) than the pictured stove-tech model. It could easily be copied and welded up out of scrap steel plate. Rocket stoves ROCK: why gather and burn more wood than you have to? In addition to burning it much more efficiently. Great post on appropriate tech..... thanks.

    1. Hi Gomez,

      Those ARE nice stoves ( thanks for pointing them out.

      I notice the Heavy Duty model has a briquette accessory, which might work for some bio-briquettes, as well.

  2. I would like to know the bio-briquette recipe. I have been amazed at the heat output and longevity of the pressed fire logs that are 100% wood sawdust. If I could make a contraption to let the ocean depth be my press, I could make my own compact fuel briquettes for the boat stove. Always looking for something to burn hotter and free from the forest.

    1. Hi Ken,

      Here are some bio-briquette recipe, tool and info links:

      The first is general, the Legacy Foundation is recommended by Rok Oblak (Holey Roket Stoves) and others, while the third is DIY-candy.

      RE: Ocean depth press - There's a wood artist in Tenakee Springs, AK who uses that method for his glue-ups. His 'device' is plastic wrap. Sends the wrapped (water-proofed) item down in a crab pot. For briquettes, you might have to at least partially dry them, first.

  3. Hi,

    On WAYWARD, we have a small wood range with a fixed stack, deck flange, more stack and smokehead.
    We send it through the deck at right angles (canted outboard), so the 'leveler' is dead simple... we level the smokehead by adjusting its struts.

    On MUSTELID, we built a smokehood that fits over the top of our EcoZoom Versa Rocket Stove (we can flip it up and remove the stove for outside use). From there it's about the same deal, except that, since RSs push their exhaust with thermal expansion, we don't need extra stack between deck flange and smokehead. This helps keep the aft deck clear above shin height.

    Small Boats Magazine (about to change it's name) is putting out a 15 part video series on MUSTELID, starting 7 July 2023. I THINK it will be at their YouTube channel, @smallboatsnation., and will be released one part per week. Part 4 Outfit will have a section on the stove installation.

    Hope this helps!

    Dave Z