A dash through Nairobi streets paints a grim picture of a city chocking in its own garbage. The garbage problem in the city is like a multi-headed serpent. If you chop one head, another emerges.
Everyday 3,000 tonnes of trash are collected. In fact, the county government has admitted that the rate at which Nairobians are generating waste surpasses its capacity to handle it.
Now, with the introduction of a simple stove that uses rubbish as a resource to produce heat for cooking, the amount of garbage sent to dumpsites could be reduced by about 50 per cent as well produce fuel that is relatively clean and more energy-dense than normal firewood. The community cooker is a sustainable community energy system invented by Planning System Services. It is made of welded steel insulated with firebricks.
The top of the cooker is made of five or six cast iron plates, which serve as cooking surfaces. It has an oven that can be used to bake several loaves of bread at a go and storage capacity for heating more that 500 litres of water.
A flue channels the smoke from the combustion chamber to the chimney’s outlet high above the roofline. Garbage is sorted out to remove rubber, glass and metal and stored in a three-step mesh rack next to the cooker.
Once dry, the rubbish is bundled to the size of football and pushed through a wide metal chute by a cook operator into the firebox, which burns it hot enough to destroy toxins.
“The cooker burns rubbish at over 850 degrees Celsius producing almost odourless white smoke, achieving 99 per cent combustion within the World Health Organisation minimum standards for incineration in developing countries,” says Wakina Mutembei, the Community Cooker Foundation Manager.
Due to its huge size and high rubbish consumption rate, it is suitable for institutions such as schools, children homes, hostels, hospitals, hotels where there is continuous cooking as well as a larger number of people as opposed to domestic use.
It is a cheaper option to charcoal, firewood, gas and paraffin, the main of source of cooking energy in most institutions.
“We offer training in solid waste management to ensure that non-combustible materials and material, which create harmful fumes are intercepted and removed, such as torch batteries, spray cans, glass and rubber. Biodegradable scraps that fall through become compost manure.
The rest of the trash as as paper, plastic bags, textile, packaging and even food scraps, are placed on the second tiered rack for drying. Dry materials are bundled and burnt,” Mutembei says.
It is also deliberately designed to be labour-intensive and to use locally available materials so that members of communities and institutions can easily carry out repairs, maintenance and operation.
The cooker can be used non-stop by institutions or community groups to cook food for their own use or as an income-generating activity. “By use of this cooker, institutions will not only be helping to clean up the local environment and save their fuel costs, but they will also contribute indirectly to forest protection,” she says.
Four institutions are currently actively using the community cooker including Mirema School, Kawangware Children’s Garden Home, Presbyterian University of Eastern Africa, Mathare Community Centre and another one is under construction Naivasha Mixed Secondary School.
At Mirema School, the cooker cooks for 770 pupils two times a day for all the children and staff and three times a day for boarders. The school has saved up to 87 per cent on firewood costs.
They used to consume 500 kilogrammes of firewood per week cooking on firewood jikos, which is 7,000kg per term of 14 weeks. That translates to about Sh300,000 saved every year.