Bananas are eaten raw, fried and baked; they are also used to produce banana beer and wine. However, the fruit is only a small percentage of what the plant produces. The rest – skins, leaves and stems – is generally left to rot as waste.
Now scientists at The University of Nottingham, Britain, are looking at ways to use that waste to produce fuel, developing simple methods of producing banana briquettes that could be burnt for cooking and heating.
PhD student Joel Chaney in the Faculty of Engineering has developed a method of producing the briquettes using minimal tools and technology, which could be used in communities all over Africa. Other waste products can also be used.
With bananas, the banana skins and leaves are mashed to a pulp in a hand-operated domestic meat mincer. This pulp is mixed with sawdust (or, for instance, sun dried banana stems) to create a mouldable material. Then, the pulp mix is compressed into briquette shapes and baked in an oven at 105°C. In Africa the fuel could be left for a few days to dry in the sun.
Once dried, the briquettes form an ideal fuel, burning with a consistent steady heat suitable for cooking.
"A big problem in the developing world is firewood," said Chaney. "Huge areas of land are deforested every year, which leads to the land being eroded. People need fuel to cook and stay warm but they can’t afford the more expensive fuels, like gas.
"As well as the environmental damage this causes, it also takes a lot of time. Women can spend four or five hours a day just collecting firewood. If an alternative fuel could be found they could spend this time doing other things – even generating an income."
Chaney’s supervisor Dr Mike Clifford, associate professor in the Faculty of Engineering, says: "We’ve been able to turn all sorts of waste materials into fuel and to predict how well different mixtures of materials will burn."