RE: [Biochar] New stacked fuel cookstoves with brick walls in Africa – renewable fuel, less smoke, char.

Kevin,

This is really great.   “stacked-fuel” stoves have (IMO) great potential in the institutional category of cooking.   Larger pots and more heat and more space to put the cut fuel.

Some suggestions that you might have already considered:

1.  For a modest one-time cost, consider having two rails on which the large pot could SLIDE to the other cooking position.   I suggest two parallel pieces of 90 degree angle iron, upside down sort of like this:

Pot è        |________|

Rails è         ^           ^

Bricks è  BBB          BBB

Also nice if under or between them would be 2 (maybe  3 or 4) cross pieces to keep them securely spaced.   Sliding will allow the use of even larger pots (that can be too heavy to lift when full) and/or so that smaller people (female cooks,
not two strong men) could do the sliding.

2.  Also consider having a pot skirt to  keep the flames close to the  pot.

3.  Adds more expense, but portable (removable) barriers on the back side and/or on the front side could keep in the flames under the pot while protecting the legs of the cooks / pot-movers.   Be sure to have spacers at the bottom and top
for the entry of the necessary ambient air for the nice combustion.  

4.  The name “top-down burn” (with stacking of fuel) is good and descriptive.   Not to be confused with the Top-Lit UpDraft (TLUD) technology pioneered by Tom Reed and Paal Wendelbo (and named by me in 2005 when the Champion TLUD received
recognition.))     TLUD has some additional expectations (and expenses) that should not be objectives or inclusions in the top-down technology.   You have something different that needs to be recognized separately.

5.  Again as some  small expense, consider having a metal  sheet (corrugated roofing is excellent) to be under each stack of fuel.   Let it extend a bit to the front and back so that it can be “handled” for transfer of the biochar into
some container / extinguisher.    A couple of longer  pieces of re-bar (wired to the curve of the roofing material) will make handling the biochar (and ashes) much easier and safer.

Best wishes,

Paul