In June my friend Aldo and I attended a training: how to
construct “cocinas mejoradas” (better or imporoved stoves) in La Libertad, the
departamento next to Lambayeque, where we live. “Improved stoves” is really a
misnomer, what cocinas mejoradas do is replace no stove at all, they’re for
people who cook in their houses over open flames from fires fueled by wood.
That practice is indeed as bad as it sounds, the walls of their kitchens are
black with soot and you can deduce from that what the lungs of the poor women
who cook over those fires must look like. They also get cataracts from years
and years of exposing their eyes to the heat and smoke.
A cocina mejorada is essentially a very efficient
pot-bellied stove. A chimney provides draft, the fire burns hot in a very
confined space and uses much less wood than an open fire or “fogón.” The health
incentive probably wouldn’t be enough to convince many families to use a cocina
mejorada but that, paired with the economic benefit, is often enough to change
their minds.
Aldo is an “albañil”—a bricklayer—so he was the right man
for the job. We finished our stove in about eight hours spread over two days.
Here’s how the work proceeds:
First you pour the “losa,” a slab of concrete that forms the
stovetop and burners. It’s made of concrete so as to be resistent to heat. You
trowel the concrete over wire mesh and rebar, which provide internal
reinforcement. The preparation time is about two hours, more when there’s
competition for materials and tools from 15 other Peace Corps volunteers and
their community partners.
While the losa is drying you construct the base of the
stove, made of adobe bricks held together with mud. Because the dimensions of
the base and all the parts of the stove are standard and—due to engineering
tolernces—unalterable, you have to hack up adobes with a machete to make them
fit. Here’s Aldo constructing the base:
Next you construct the most important part of the stove, the
“cámara” or combustion chamber. It’s made of fabricated clay bricks, seventeen
of them, in order to be more resistent to the intense heat generated inside the
stove. The interior of the cámara is 14.5 cm square, it’s height is 38 cm.
These measurements evidently are ideal for the efficient generation and
conduction of heat.
After you construct the cámara you basically bury everything
in mud. You encase the cámara en adobes, then fill in all the gaps. Next you
construct a low rim around the “mesa”—the upper surface of the stove—using
chopped-up adobes. Into the exposed part of the mesa you shovel “barro
mejorado” (better or improved mud), which is mud mixed with straw, goat shit
and ashes to ensure better cohesion and better resistence to heat. You trowel
the imporoved goat shit onto the mesa, using the same two pots you used when
you poured the losa to define the positions of the two burners. You cut out a
bit of extra space to allow heat to flow up and around the pots while food is
cooking and a tunnel that allows heat to flow from one burner to the next and
finally to the chimney.
Next you construct the chimney, which needs to measure
exactly two meters, say the engineers. These two meters can be pure metal (more
expensive) or adobe and metal as was the case with our chimney.
Finally, you install the concrete losa, seal it in place
with mud, and attempt to light the stove. In order to better accommodate a
fire, you need to rub down the still wet interior of the stove with ashes, then
you plug one burner, drop a wad of paper and some splinters of wood down the
other, then drop a lighted wad of paper into the hole and, if your lucky, the
draft created by the combustion chamber sucks a pillar of flame up and out of
the burner and you’re in business.
The owner of the new stove is very happy. Ideally, she’ll
paint the walls of her kitchen, maybe the stove, too, and neither she nor
anyone else in her family will die of or fall ill from a respiratory infection.
Since the stove will burn 60% less wood than did her open fire, the stove and
stoves like it will help slow global warming and deforestation. Not bad for 150
soles, fifty bucks.
Aldo and I plan to build ten in the next two months in
Callanca and, if the owners seem happy with the results, fifty more in the next
year.
Posts
