[Stoves] (stoves) Haitian cooking

Crispin Pemberton-Pigott crispinpigott at gmail.com
Wed Jun 29 17:25:13 CDT 2011


Dear Tom and All

Having done quite a number of tests in Maputo to establish the cooking
efficiency of stoves using uncontrolled cooking tests (UCT), the result came
back with the following: the number of grams of charcoal per kg of meal was
related not only to the device's efficiency, but to the size of the meal. In
other words there is a different answer for each meal size.

The results were expressed in the total mass of meals that could be cooked
with 1 kg of fuel. It was a 'food production efficiency' or 'specific food
production' number (SPF).

The efficiency of cooking a small meal was relatively low and as the meal
increased in size, so did the overall efficiency - that is, it took less
charcoal per kg of food as the meal increased in size.

The difference between the traditional stove and the improve stove (in that
case the ICS was the MCS / POCA) was small with small meals. As the meal
size increased, the evidence for 'improvement' became stronger and stronger.
The improved stove was much more efficient cooking average meals (42% saved)
and even better with large meals (60% saved).

So when asking the question, 'what is the cooking efficiency' or 'specific
food production' value, the answer is a formula needing the meal mass as an
input. It does not have a single answer. Stoves do not have a fixed thermal
or fuel efficiencies across a range of tasks.

As stoves can be optimised for particular meal sizes, it can sometimes be
worth the effort to tune the stove to a particular task (like heating water)
or a type of food (like a rice cooker) or regional diet (like stir fry) and
score big savings. Obviously if stoves are only tested doing one thing in a
certain way, little can be known about how it will perform in the field.

Stove science should be predictive thus incorporating the charcoal
production and the stove consumption numbers into the evaluation is
obviously beneficial.

Regards
Crispin





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