Concept
Dry dung fuel (or dry manure fuel) is animal feces that has been dried in order to be used as a fuel source. It is used in many countries. Using dry manure as a fuel source is an example of reuse of excreta. A disadvantage of using this kind of fuel is increased air pollution. In India, it is known as "dung cakes". Dry dung is more commonly used than moist dung, because it burns more easily. Dry manure is typically defined as having a moisture content less than 30 percent. "Dung cakes", made from the by-products of animal husbandry, are traditionally used as fuel in India for cooking food in a domestic hearth called a Chulha. They are made by hand by village women and are traditionally made from cow or buffalo dung. One dung cake of an average size gives 2100 kJ worth of energy. Dung cakes are also known as goitha, uple, kande, gosse or thepdi. These are the cakes of cow dung molded by bare hands with a curvature to be able to keep stuck to the walls. Once dried they are put in a pile and covered with thatch called bitauda. These bitaudas are visible in parts of rural India albeit with different names. The size and shape of the cake might vary with region. Its also not uncommon to see these cakes directly used in earthen ovens. This bio-fuel has been used primarily for two reasons: for easy disposal of cow dung and as easily available and cheap fuel. Human feces can in principle also be dried and used as a fuel source if they are collected in a type of dry toilet, for example an incinerating toilet. Since 2011, the Bill & Melinda Gates Foundation is supporting the development of such toilets as part of their "Reinvent the Toilet Challenge" to promote safer, more effective ways to treat human excreta. The omni-processor is another example of using human feces contained in fecal sludge or sewage sludge as a fuel source.
