Kibera Letter Rob CrillyAs a solution to one of the developing world's most pressing environmental problems, the giant, concrete-clad oven seems a trifle, well, toxic.
Choking black clouds of smoke are billowing from one end, while a stinking stream of plastic bags, battered trainers and maize cobs is being stuffed into an incinerator box at the other.
None of which seems to bother the men and women of Africa's biggest slum who are queuing to use the community cooker.
Pans filled with water are coming to the boil on its hotplates, ready to make chai - the gently spiced, milky tea loved by all Kenyans.
And pots filled with pasta are simmering inside the oven, where temperatures reach 500 degrees.
"It might smell a bit but it doesn't make our food taste any different," says Virginia Wamaitha, as she pours sugar into her steaming pan of chai. "It will taste just like chai should."
The principle is simple. Kenya's slums are awash with rubbish. With no refuse collections, the open drains are clogged with plastic bags, goat bones and empty tins creating a fetid, disease-ridden hell.
At the same time, the country's forests are dwindling, cut down to produce charcoal for cooking.
So why not use the rubbish for cooking? If the pilot project in Kibera - a cramped, stinking shantytown of one million people - works, it could offer hope to slum dwellers as the world faces up to an explosion in urban living - and the waste it creates.
Pauline Nyoto, of the Umande Trust, which runs the pilot project, says the benefits are clear.
"It is only a pilot and we need many more cookers to clean up Kibera, but we have already seen a difference in the area we are targeting. The drainage ditches are much cleaner - just waste water when before they were clogged with rubbish."
The project is the first of its kind, according to the United Nations Environment Programme which provided €7,500 for the launch.
Youth workers are paid a few shillings a day to go door-to-door collecting rubbish. They are also allowed to use the cooker for preparing hot meals or to fill buckets with hot water for washing. The target is for the cooker to consume half a ton of waste every day. Its success has already prompted the country's biggest supermarket chain to pledge funding for 20 more.
Kibera's problems with waste are mirrored in Nairobi's other slums and are the result of rapid, unplanned expansion as families give up their rural way of life for the city.
It's a trend seen throughout the developing world.
Earlier this year the UN Population Fund reported that for the first time more than half the world's 6.6 billion inhabitants would live in urban areas by 2008.
Without adequate planning, warns its State of the World's Population 2007 report, there will be an explosion of slums, with the associated environmental damage and human disease.
"The changes are too large and too fast to allow planners and policymakers simply to react," it concludes.
Nairobi's unplanned sprawl is already reaching crisis point.
Henry Ndede, of Unep's Nairobi River Basin Project, said rubbish from the city was killing off Kenya's famous plains.
"The degradation of the environment of the Nairobi rivers is reaching a critical stage. With the increasing of population now to more than three million people, the waste problems have actually overwhelmed the ecosystem," he said, adding that the city now generates 3,000 metric tons of waste a day.
Governments in the developing world are slowly waking up to the problem.
Architects in Nairobi have even suggested moving to a new capital to allow planners to start afresh, ensuring adequate roads, refuse dumps, clean water and sewerage.
That is probably a pipedream.
For now the biggest battle is tackling the scourge of the plastic bag.
They block drains and kill livestock that eat them. They help spread malaria by holding warm pools of water - the perfect habitat for mosquito larvae. They choke soil and plants, and bleed chemical additives into vegetables and fruit as they grow.
The phenomenon began in the late 1990s when new technology made production cheap and easy. The consequent throwaway culture meant plastic bags quickly became an ugly but ubiquitous part of the African landscape.
At one time, Kenya was producing 4,000 tonnes each month.
Several countries are trying to reverse the trend. South Africa, Uganda and Kenya have all introduced minimum thickness rules. Others are slapping levies on plastic bag production to encourage shoppers to reuse them. The measures have yet to have much of an impact in Kibera.
Plastic bags hang from trees, get snagged on barbed wire and mix with the mud underfoot.
Many have been used as "flying toilets" - filled with excrement and then hurled into the narrow dirt streets.
And then there's that acrid smoke to deal with as they burn in the community cooker.
George Arabbu, an architect with Planning Systems, which designed the cooker, admits the smoke is a potential hazard but that the people of Kibera cannot wait for a perfect solution.
However he adds : "At the end of the day, it's a case of weighing risk against benefit and the rubbish itself is a menace."