of irrigated land yields about five tonnes of rice and a tonne of husks. Rice is a staple food in Benin and typically parboiled - a process of partially cooking rice in the husk before it is milled. Parboiling requires a lot of heat, which means a lot of wood and is a big contributor to health problems due to the inhalation of wood smoke.
Benin's an annual deforestation rate, one of the highest in the world.
On average, the amount of husk produced per season. Benin's rice farmers struggle to get rid of the husk as they are no good as animal feed and take a long time to rot, so can't be used as compost. With no other option, millers often just set the husks on fire, spewing smoke into the air.
Africa Rice Center (AfricaRice), a pan-African rice research group spent in designing and testing, before it figured out how to turn the mountains of rice waste into fuel.
countries - Benin and Nigeria - in which the husk-burning stove was recently approved for commercial production, and AfricaRice is now teaching metal smiths in how to make it.