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10 Woods, who serves as Sanivation’s C TO.
Having the ability to fill that need and being
able to adapt their product for different uses
are the most thrilling parts of Sanivation’s
work for Woods. “We have never had a solid
fuel that can be specifically designed to meet
users needs,” she says. “Every day we are
mixing up the recipe. Our setup allows for that
kind of tinkering and that gets me excited.”
years old. They started with an idea for a solar
toilet, which gradually evolved into something
radically different: a subscription-based waste
collection service for urban communities.
Seventy percent of sub-Saharan Africa’s
nearly one billion people do not have access
to hygienic sanitation facilities. Many ( 30
percent) still practice open defecation and
the rest use communal pit latrines, which are
unsanitary and often dangerous. Assaults
on women and children are common around
these stations, as they are often unlit and
located away from where people live. Woods
witnessed many of the problems firsthand
while working on sanitation infrastructure
projects in several countries, Kenya included.
“Many women and children stop drinking liq-
uids after 5 p.m. so they don’t have to use the
toilet after dark,” she says. “The number one
reason people use our service is because they
want access to a safe toilet in their home.”
It took years for Foote and Woods to arrive
at the concept of turning human waste into
fuel, but once they did, they discovered that
their market is enormous. A recent United
Nations report cited that human waste, if
harnessed as an energy source on a global
level, has the potential to generate energy
for 138 million homes, and estimated that
the market for human waste as charcoal
could be worth US$9.8 billion. In Kenya,
Foote says that feces-based charcoal has the
potential to meet 50 percent of the country’s
charcoal demand.
“Even with an ambitious growth plan,
Sanivation might be able to reach 0.5
percent of the market in the next five years.
That’s about $5 million in annual revenue
from what used to be a waste product,”
he adds. Other ventures are also developing solutions in different segments of this
space, like Nairobi-based Sanergy, a company that uses a franchise toilet model and
transforms the end product into electricity
and fertilizer.
THE BUSINESS OF SANITATION
Woods and Foote formally launched
Sanivation in 2014 as comprehensive service,
offering everything from in-home toilets
to the production and sales of waste-based
charcoal “briquettes.” The venture offers a
subscription-based sanitation service, where
customers pay a monthly fee of 600 Kenyan
shillings (about US$6.50) for a Sanivation
employee to install a toilet and then pick up
the waste t wice a week and transport it to
Sanivation's work site.
At the site, the feces is transferred into repur-
posed metal paint drums, which are attached to
large parabolic mirrors that act as solar energy
concentrators. As the sun beams down, it
heats the waste to a high enough temperature
to deactivate pathogens. The exact amount
of time Sanivation leaves the waste in the
concentrator depends on how bright the sun is
on any given day. If the temperature in the metal
drums reaches 85 degrees Celcius, one hour is
sufficient. If the drums only reach 65 degrees,
the waste stays for six hours.
As human poop is heated, it transforms
into a sticky substance because of its high
lignin content, which is basically insoluble
plant fiber. Heating lignin transforms its
chemical bonds, turning it into what Woods
and Foote found is a perfect binding agent
for a non-wood-based charcoal briquette.
After the waste is treated, it is processed
in a mixer to homogenize its composition,
and then it is combined with rose waste from
local flower farms. (Naivasha, which is in
western Kenya, is a major supplier of roses
throughout Europe, so rose waste is plentiful
in the region.) Prior to mixing the rose waste
with the poop, Sanivation carbonizes it in a
carbonizer and then grinds it into a powder in
a flower mill. The resulting powder is mixed
with the heat-treated feces, and the mixture
is put into a slowly turning agglomerator,
where the briquettes naturally form as a
result of centripetal force, like a snowball
rolling down a hill. The briquettes are then
put out to dry on tables made of chicken
wire. It takes about three days for the
briquettes to be fully dried and ready for the
market, where they sell for roughly the same
price as standard charcoal, which costs about
$0.30 per kilo in Naivasha.
The endeavor might seem fairly straight-for ward, but Woods equates it to running 10
companies at the same time. “It is complicated and difficult, and the only reason we are
handling all of the steps right now is that we
have to prove all of this first,” she explains.
Her vision is to eventually produce the binder
only and sell it on to others “who are better at
making briquettes.”
A CREATIVE FUEL RECIPE
Sanivation is not the first to use alternative
materials to create charcoal. One organization that Woods encountered in Naivasha had
some success combining molasses and charcoal dust. Others have used cassava, acacia
Human waste has the potential to generate electricity
for 138 million homes and become a US$9.8 billion
charcoal market globally.
