A new project is using solar energy to transform toilet waste into efficient cooking fuel, in an initiative to improve hygiene for people in communities without indoor sanitation and at the same time reduce the felling of trees for charcoal.
In the communities around Naivasha, about 90 km (56 miles) northwest of Nairobi, Sanivation, a Kenyan social enterprise, a for-profit company also focused on social good, has begun providing toilets to homes that lack proper sanitation.
The locally made toilets, called "Blue Boxes", are portable and require no fixed plumbing. Users pay a monthly charge to have them serviced twice a week.
The health implications for a community with little access otherwise to modern toilets is significant, said Dr. Oren Ombiru, Naivasha’s health officer.
The leading cause of death for children under five in Kenya is diarrhea, a problem exacerbated by poor sanitation, he said. Most homes in semi-urban areas do not have indoor plumbing, and some people have no choice but to defecate outdoors, he said.
"Safe waste disposal is one of the best ways to prevent diarrhea. This is a challenge for the vast majority of peri-urban dwellers, who are mainly low-income people,” Ombiru said.
Around 80 toilets have been provided so far, serving over 400 people. But it's what happens to the waste after it is collected from the toilets that makes the project more than a simple effort to improve sanitation.
Mix, cook, and burn
The waste is mixed with charcoal powder and with waste plant material from nearby flower farms, which has been burned and crushed into fine powder.
Sanivation uses solar technology to concentrates the sun’s rays and heat the toilet waste to a high temperature, sterilizing it and making it safe for reuse.
The mixture is turned into smokeless briquettes that people can buy for cooking at home.
Benjamin Kramer-Roach, director of energy at Sanivation, says theirs is one of very few projects that use this model to transform human waste into solid fuel.
Naomi Wanjira Chege, a mother of three children from Karagita area, about 15 minutes' drive from Naivasha, has been using a Blue Box toilet at home, and cooking with Sanivation’s briquettes for a year.
"The fact that the toilet is portable means that it can be used in any room of the house. So you don't have to worry about getting outside to use the toilet," she said.
Chege uses half a kilo of the briquettes to cook a meal. Although at 25 shillings ($0.25) per kilo they cost a little more than she would pay for ordinary charcoal, she says they burn for longer – up to four hours.
"You don't keep adding fuel when cooking, given that it can last for a long time," Chege said. Another advantage is that the briquettes produce no smoke or odours, she said.
"When customers use our briquettes, bought at a higher price than charcoal, the efficiency from the long burn time actually saves them 10 to 15 percent per month on fuel costs,” Kramer-Roach estimated.
He pointed to sales of 5 tons a month as evidence that the price hasn't put people off.
Since the briquettes burn longer than charcoal produced from wood, every ton sold saves the equivalent of 88 trees, he said.
The toilets are popular, too, he said. Sanivation installs them without cost but charges a monthly fee of 600 Kenyan shillings (about $6) to remove the waste.
Kramer-Roach acknowledged that this cost is hard for some people to afford. But "because the payment is monthly, we have found people are able to plan ahead and save just like they would for electricity or rent," he said.
Although users can choose to end their subscription to the service each month, the re-subscription rate is over 90 percent, he added.
People choose the service because it offers them a chance to have a clean toilet in their own home.
"All toilets are odorless and allow everyone, including elderly and disabled users, to use the bathroom with dignity and safety," he said.
Sanivation processes one tonne of toilet waste each month, and the Kramer-Roach said they hope to triple that in the next six months.
He believes the portable toilets could also be used in environments such as refugees camps where there is a high demand for simple sanitation.