They call them “flying toilets” – the bags of human poo that are thrown out of the windows of the thousands of small shacks that make up Nairobi’s slums.

The largest of Nairobi’s informal settlements is Kibera, just three miles from the city centre. An estimated one million people live there, and toilet facilities are scarce. The bare earth streets are carved with gullies: equal parts open sewer and rubbish dump. The nearest toilet for most people is a hole they have dug in a bare patch of ground at the back of their shack.

But Josiah Omotto, a managing trustee of the Umande trust, has high ambitions: he wants Nairobi to become an open defecation-free city. It’s a big challenge to set for yourself. “If open defecation was banned in Nairobi today, every member of the informal settlements would have to queue for two days to use the existing toilet facilities,” he says.

Umande and the British charity Practical Action have devised a solution that turns the mountains of odorous human waste from a problem into an asset.

They are building bio-centres – toilet facilities where human slurry is collected and put in a digester which collects the methane emitted from poo as it breaks down. The methane is sold back to the slum dwellers as biogas, used for cooking within the centres or to power hot showers.

“Every individual creates 300g of human waste each day, and 60% of Nairobi’s four million inhabitants live in its informal settlements – that’s 2.4 million people,” says Omotto. “What we have in Nairobi is 720,000 kg of shit. We want to turn it into biogas so that we can tackle the energy crisis.”

Methane is a greenhouse gas. If released into the atmosphere it is many times worse for the environment than CO2. Steps are being taken worldwide to reduce emissions but since we humans are likely to carry on defecating for many years to come, human poo could be considered the ultimate source of renewable energy. It’s much better for the environment to burn the methane from poo than from fossil fuels, after all.

Umande and its partners have built 57 biocentres in Nairobi, which have so far managed to collect at least 60,000 kg of poo, according to Omotto.

Some biocentres also have other facilities incorporated within the same block, including spaces for recreation, social activities and small businesses.



The Stara biocentre in Kibera is run by women who also manage an orphan school. At the bottom of the centre they offer hot showers powered by biogas, and the first floor is let out as a legal advice centre. The orphanage earns 45,000 Kenyan shillings a month from the biocentre, which they use to fund their work with the children.

Aidah Ebrahim, project director for Umande, says that between 350 and 1,000 people visit each of the toilet blocks every day, paying three cents each to use the loo, and a few cents more for a hot shower, if those are available.

But the project was not without its challenges. Transporting heavy building materials across dirt streets riven with gullies and piled high with detritus is not easy, and theft of building materials is commonplace in Kibera. Umande held negotiations and the community helped to transport the building materials, and keep them secure while the facility was being built.

“Most of the projects are funded by grants from donors, but since last year we have partnered with financial institutions who are providing loans to pay for future sanitation projects,” says Ebrahim. “This came after we definitively proved that the projects are bankable, profitable and scalable.”

Umande is working with engineers from Denmark and the Netherlands on converting the bioslurry into fertiliser, and to see how we can recycle the water. They are also working with a private company from Thailand to bag large quantities of gas for resale to small businesses in the city. In the future, Umande would like to incorporate solar panels to buildings and biodigesters to existing toilets so that they do not have to build completely new facilities to create energy.



Practical Action is replicating the project in other countries. In Vattavan, Sri Lanka, they power their digester with animal waste, providing cooking gas and lighting in rural areas. One of the project’s fans is Sakunthaladev Kathiravetpillai who lives with her husband and four children. She used to spend each day collecting fire wood for cooking but now she uses biogas and has more time to grow food, or earn money for the family. She uses the dried out manure that is left after the poo has decomposed as fertiliser on her vegetable garden.

This week, Umande broke ground on the first of a series of toilet block biocentres in a slum in Kisumu, near Lake Victoria. City officials reached out to the group after seeing the success they’d had with the biocentres in Kibera. It seems the renewable energy potential of poo is an idea worth spreading.



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