[Stoves] ***SPAM*** Cooking Hole Modification to Three Stone Cookstove - Update

[Robert Taylor]

Hi Kevin

Very interesting. What's the significance of the hole size and shape, 25 
x 25 x 25 cm? Is it optimal for good combustion, or simply convenient 
based on pot size and fuel quantity?

Best regards

Robert

On 22-Jun-22 5:13 AM, K McLean wrote:
> Adding a 25x25x25 cm hole to traditional open-fire cookstoves may end 
> the collection of firewood from forests in many areas.  By piling fuel 
> in the hole beneath the cookpot and lighting the pile on the top, the 
> fuel burns long, hot, with no tending and with less smoke.  And by 
> quenching the embers, cooks make biochar.
>
> We found that most woody biomass bigger than thin twigs burns well in 
> the cooking hole <https://youtu.be/DmzQFCp2kNI>.  Firewood the size 
> that is typically burned in unmodified three stone cookstoves burns 
> for three hours without tending.  Much less smoke is emitted than from 
> an unmodified three stone cookstove.  A colleague estimates that the 
> amount of wood in the cooking hole would burn for 30-40 minutes in an 
> unmodified three stone cookstove.  Here's a video 
> <https://drive.google.com/file/d/15V4vTJxO1Lcm0wFzB96pQT9jvgjaXkwh/view?usp=sharing>. 
>
>
> Thick twigs burned without tending for 1.5 hours.  Thick twigs and 
> small branches are abundant and unused in much of Africa.
>
> The cooking hole also works with crop waste (maize stalks and cobs, 
> cassava stems, banana peels, bean stems, ...), elephant grass, bamboo, 
> large sawdust and wood shavings, sawdust briquettes, dung patties and 
> more.  Depending on the fuel, the fire will burn without tending for 
> 20 minutes to several hours.  Here's our training video 
> <https://youtu.be/DmzQFCp2kNI>.
>
> Women can:
>
>     - All but stop collecting firewood.
>     - Leave the kitchen to do other things once they start the fire.
>     - Make biochar.
>
>
> And 8-12 common bricks can support two cookpots over one cooking hole 
> allowing two meals to be cooked with the same amount of fuel and time 
> it takes to cook one meal.  The time to boil is only a few minutes 
> longer than for one pot.
> 2 burner drawing.jpg
>
>
> In much of Africa, most people know how to make bricks.  We show them 
> how to make free custom bricks to line the cooking hole.  Here is a 
> video 
> <https://drive.google.com/file/d/1b2WvePKX_ofnELUWhexqQZR4NyCrXxnH/view?usp=sharing>.
>
> Kevin McLean
> Sun24
>
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