[Stoves] Simple Modifications to Traditional Wood Cookstoves - Rocks and Clay Grates

[K McLean]

Sun24 and its partners operate at the primitive end of the cookstove
spectrum.

We have found that both rocks (or broken clay bricks) and a clay grate
improve open-fire wood cookstoves' efficiency.  Here are examples of rocks
and a clay grate in a three-stone cookstoves:
[image: Rocks in 3-stone.jpg]
[image: Clay disc grate in 3-stone stove.jpg]
SNV tested
<https://drive.google.com/file/d/183kPF5DrwIR5mdDhE7xC9AaNJLaorGZt/view?usp=sharing>
the rocks and clay grate in its open-fire stove.  Here are SNV's results:

Rocks vs unmodified open fire

+30%    Thermal efficiency

-27%     Wood fuel used

-53%     CO

-57%     PM

Clay grate vs unmodified open fire

+52%    Thermal efficiency

-47%     Wood fuel used

-57%     CO

-58%     PM

Early user feedback suggests that rocks in traditional charcoal cookstoves
also improve efficiency.  We are expanding our informal field testing and
hope to test in the lab soon.

Since rocks and broken clay bricks are free and ubiquitous, we only need to
disseminate the idea, not a product.  We are rapidly disseminating the idea
with success in Kenya, Uganda and India by training women group association
leaders to train others who then train at the local level.  In Kenya and
Uganda we are working with the Catholic and Anglican Churches.  In just a
couple months and at low cost, we have trained tens of thousands of women
to use this simple modification.  The trainers' feedback is that the users
love it.

Here is our occasionally-but-not-frequently-enough updated Cookstoves
Overview
<https://docs.google.com/document/d/1ZryS7gQ1q3zKLZPM2KcXdtIHbOYQp4PbloPqMvrlZ5Y/edit?usp=sharing>
.

These cookstove modifications are a transitional first step but they are
important.

All suggestions are welcome and appreciated.

Kevin

*Kevin McLean, President*
*Sun24*

*https://sun24.solar <https://sun24.solar>  Sun24 Cookstoves Overview
<https://docs.google.com/document/d/1ZryS7gQ1q3zKLZPM2KcXdtIHbOYQp4PbloPqMvrlZ5Y/edit?usp=sharing>*
*Tampa, Florida, USA*
*+1 (813) 505-3340*
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