Adventures with the Rocket Stove

The two-pot top with damper control didn’t quite work as intended and was soon discarded. It is now a one pot, stove used only when there is a large gathering. Finally, there is too much steel and fabrication that went into this stove.

That set me thinking. The core strength of a Rocket Stove idea is its simplicity. It seems quite the wrong thing to walk away from this virtue.
There have been numerous variations of the idea for many purposes. However, the simple idea, capable of being cheaply, locally self-built appears to have been seduced by globalisation. There are instances of the stove being mass produced in China and distributed worldwide by well meaning souls in the West. Here are two examples, the EnviroFit and StoveTec. It would be interesting to compute the total energy cost of these stoves; even the monetary cost in India at least, is unaffordably high.

I revisited my Rocket Stove design. The new design objectives were these: use natural materials, keep costs low, design for cooking a maximum of 1kg of rice, make it locally. I talked with my potter friend Ramalingam showing him some sketches. He made a couple of samples that I tested out.

The defining issue was the height. Somewhere between 15″ and 18″ is the ideal height; if side higher, the flame doesn’t lick up and if lower, a sufficient updraft is not induced. The fuel feeding mouth is about 4″x4″. There are tiny holes on the walls of the fuel chamber through which thin rods can be inserted to form a grate. Placing fuel sticks on top of this would leave a clear space below for drawing air. But in practice i found this unnecessary. If one takes enough care not to stuff the mouth with firewood enough space remains for drawing air.

In about 3 months after 4 prototypes, we had the right one. As you can see, it’s a pretty one too. It was a pity to conceal this work of art in mud but I had to do it in the name of fuel efficiency. The earth acts as an insulator and the skirt delays the flame licking out wastefully heating the ambient air; instead, the skirt directs the flame over a greater surface area of the cooking vessel. I have two such encased Rocket Stoves functioning now. User feedback is good.

In India good ideas need not be evangelised. They are copied or adapted in quicktime. I may distribute about ten such stoves and see what reports I receive from housewives. Quite apart from the pompous motive of saving the planet, I have a less lofty one: I want Ramalingam to have a new product line so that he’s always there in business, to develop new ideas with. May be the village of Dargas where there were once tens of potter families [and now alas, but two] will revert to its tradition again.

10 thoughts on “Adventures with the Rocket Stove

  1. sujatha…
    firewood remains the fuel for a majority of india’s poor. one is better off reducing the quantities used and making them smoke free. that’s what rocket stoves do. in any case, use of twigs and brushwood found in neighbourhoods is quite sustainable.
    briquettes are a good route too but they need a centralised unit and some manufacturing skill. they’d certainly be wonderful if they are easily available everywhere, which they are not. till that catches on efficient smoke free stoves seem a good bet
    -dv

  2. sujatha…
    stoves achieve freedom from smoke by ensuring sufficient updraft, which makes plenty of air for combustion available. how do they manage that is the issue. the designs you have flagged use tall chimneys, which are good if they are affordable.
    then comes replicability at user level.
    evaluated from these points of view, pointReturn’s pottery Rocket Stove appears to have some advantages
    -dv

  3. dear sir,
    with reference to efficient wood burning stoves,have you heard about the sarala ole and the astra ole?there is some information regarding them here –
    http://www.ias.ac.in/currsci/oct102004/926.pdf
    http://www.teri.res.in/terragreen/issue42/feature.htm
    http://www.tide-india.org/products/06household-cooking-stoves.html
    http://www.pciaonline.org/files/Proceedings/2007IndiaProceedings/pdf/1.8%20Srinivas.pdf
    what do you think about them as compared to the rocket stove?
    warm regards,
    sujatha

  4. Hi DV
    May ramalingam and his folks have busy schedule. I had seen stoves made from tin with a small hole near bottom and centrally packed with husk being used. its cost was about 40Rs 30 years back but only packing husk was a skilled issue. may this news spread to many in our myriad villages. thannx

  5. Hi DV,

    Very interesting. One question though. I have seen pot based stoves in my village when I was a kid ( about 25 yrs ago)but they were open and not rocket science ( i mean rocket stove technique).

    How do you handle the issue of ashes accumulating from burnt out firewood? did you face that issue?

    May a ‘pushin – pullout’ removable base layer underneath the vertical shaft separated by a steel grill collect all the ashes that can be removed ?

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