Char-briquettes from crop residues
Every year the sugar cane fields of Maharashtra State in India produce a staggering four and half million tonnes of leaves, which are left behind when the cane is harvested. The leaves contain lignin and silica, so they don't decompose easily, and they aren't good for animal fodder. So what can be done with them? Traditionally, the answer has been to burn them in the field.
The Appropriate Rural Technology Institute of India (ARTI) came up with a better solution. It developed a special portable kiln that burns the leaves to produce char. The powdered char is mixed into a paste with water and a binder, and a hand-operated press is used to turn the paste into briquettes, which are then dried in the sun. ARTI has developed the efficient ‘Sarai’ cookstove that uses the char-briquettes, but they can also be used in other charcoal stoves.
Charring the sugar cane trash in kilns instead of burning it in the open reduces local pollution. By replacing charcoal from unsustainable sources, it also cuts greenhouse gas emissions and deforestation. ARTI estimates that a rural family could make 100 kg of char-briquettes per day and earn about US$50 per week by selling them.