gum or clay, among other materials. But the
Sanivation briquette is possibly the most
efficient one currently on the market, and its
binding agent is certainly ubiquitous enough.
It is also more sustainable than wood charcoal
and releases fe wer particulates and about 30
percent less carbon dioxide into the air when
burned, Sanivation claims.
Paul Manda, who is Sanivation’s site
manager, previously worked for organizations
that made briquettes out of other binding
agents, but this is his first experience working
with human waste. Manda beams about what
Sanivation has developed. “If I may say so, I
think the product is super cool.” He acknowledges that there are ongoing issues to deal
with, such as teaching people how to use the
briquettes efficiently, but he genuinely feels
that Sanivation is heading in the right direction. “This is a product I am very much proud
of,” he says.
Foote says their briquette was the result
of trying to figure out where they could offer
the most value in the fuel sector, and how
they could provide a lower-cost and higher
performing fuel than what was available.
Sanivation charcoal is not a silver bullet
however, as Manda’s “efficiency” comment
suggests. One of its main drawbacks is that it
is more difficult to ignite than wood charcoal.
Also, its heating capacity is not as high,
though it burns for longer. “The calorific value
of wood charcoal is around 26 megajoules per
kilogram. Our briquettes are anywhere from
19 to 22 megajoules per kilogram,” Woods
says, which makes Sanivation briquettes better suited for cooking over a slow and steady
temperature, rather than boiling water.
The team is currently experimenting with
how to produce briquettes that can achieve a
hotter and faster burn—not as a replacement
to the current recipe, but as an alternative. “It
is not the feces binder that affects the burn
temperature but the density of the overall
material,” explains Woods. “The higher the
density, the less oxygen that can flow through
the material, so the result is a lower burn.
Standard charcoal is less dense so it achieves
a higher airflow and burns off faster.”
She adds, “Because we now have the
agglomerator, we can start playing with the
particle size or turning the machine more
slowly, so we’ll eventually come up with a
briquette that is less dense or smaller in size.”
They may have a hotter-burning briquette
ready as early as 2017.
A more pressing issue is the pace at which
they can produce their existing briquettes, for
which the demand far exceeds what they can
currently supply. “We have all of these contracts for two to three tons a month. People
say as soon as we can make more, they will
buy it,” Woods says.
Sanivation sells its charcoal to institutions
that can buy in bulk—hospitals, restaurants and
schools, for example—which means that its
charcoal customers are different from its toilet
service subscribers. The team initially tried selling their briquettes directly to households and
quickly ran out of supply, but they turned to an
institutional sales model because institutions
are willing to pay the same price at a much
lower distribution cost for Sanivation.
An obvious question is why so many
people are eagerly signing contracts to cook
food with human waste. “We get asked
about that a lot, but it’s been less of an issue
than people might think. Fuel is a big need
right now; people are looking for anything
they can use. They like that our briquettes
burn better and cleaner than local charcoal,”
says Woods. “Plus they don't look like or
smell like poop.”
THE LESS OBVIOUS S TIGMA
In fact, Woods and Foote found that the
word “toilet” was more of an obstacle when
they were setting up Sanivation because
“toilet” has negative connotations in many
parts of Africa. They named their toilet the
“Blue Box” to remove any association with
For the Blue Box, Sanivation’s design
is portable and easily made out of locally
available materials. The box part is made
out of locally sourced wood, while the toilet
seat is a standard plastic toilet seat that
Sanivation purchases at local hardware
stores (and likely originates in China, says
Foote.) Inside the box are two separate
containers: one for feces and the other
for urine. The containers are repurposed
items, like buckets and oil jugs, that are
readily available in Naivasha. A metal urine
diverter—basically a funnel that is made by
a local machinist—ensures that the liquid
waste gets into the right container.
Each toilet costs about $60 to make, but
Sanivation’s team says that it needs to eventually get this cost down to $35 per toilet.
The urine diverter proved the most difficult part of the design for the team to solve.
Foote explains that for the sake of smell, the
two types of waste have to be separated.
When left by itself, solid waste dries out
and does not smell—an important detail for
FIG 3: Fuel comparison
TRADI TIONAL CHARCOAL SANIVA TION BRIQUE T TES
Calorific Value 29 KJ/kg (100%) 19 KJ/kg (65%)
Burning Time 3 Hours (100%) 4. 5 Hours (150%)
Smoke Emitted 83ppm (100%) 27ppm (33%)
Price $0.30/kg (100%) $0.20/kg (66%)