Sunday, May 6, 2012

Kenya's Waste-to-Energy Community Cooker

An exchange between Global WTERT Council (GWC) associates Perinaz Bhada and Professor Nickolas Themelis about the the community cooker fired by solid waste operating in Laini Saba slum in Kibera, Nairobi, Kenya.

Perinaz Bhada: This community cooker in Nairobi's slum uses garbage as fuel.  Apparently, it achieves temperatures up to 850C by dripping sump oil and water onto a super-heated plate.  This eliminiates the toxins from burning the garbage.  What do you think?  Is it possible to eliminate most toxins in this way on such a small scale?  And if so, can this idea be replicated?  If the toxins can really be removed using this method, then this could potentially be a good way for getting rid of garbage in many slum areas, protecting the environment from reduced open burning, reducing the use of firewood, and providing a source of heat for cooking, heating water, etc.

I look forward to hearing your thoughts on this.
Laini Saba slum, Kibera, Nairobi, Kenya's community cooker fueled by solid waste. A waste-to-energy success.

Prof. Themelis: Dioxins and furans are formed from combustion of materials that contains some chlorine. Food wastes, green wastes and even wood contain a small amount of chlorine, PVC contains about 40% of chlorine.  Burning oil will sustain the fire but even if 850 degrees C temperature is achieved, there will still be dioxin/furans at an estimated concentration of about 100 ng TEQ/standard cubic meter (same as incinerators produced before MACT* APC**). However, the amount of flue gas from such furnaces will be small and all residential wood furnaces produce dioxins/furans but we still use them because the chimney conveys out of range of the occupants. If these African stoves are equipped with proper enclosures and chimneys that lead the furnace gas above the building where the furnace is located, they should be all right.

* MACT: Maximum Achievable Control Technology
** APC: Air Pollution Control