The two ways in which cow dung can be used as a fuel are given below.
1. Cow-dung cakes can be used as a fuel for cooking food.
2. Biogas can be made from cow dung for use as a smokeless fuel.
Biogas is a better fuel as it does not cause air pollution. After extracting biogas, the cow dung can still be used as a manure because it continues to retain all the nutrients that plants need.