Energies renouvelables, environnement-écologie, développement...
Going bananas for energy in Africa
mai 2009

Bananas provide food, wine and beer - and now maybe fuel as well

By Matt McGrath
Science reporter, BBC World Service

     You've heard of "green" fuel. Now get ready for yellow as scientists have found a way to turn banana waste into a sustainable fuel source that could be relevant to many countries across Africa.

Banana waste
Rotting banana skins are mashed into a pulp, then mixed with saw dust

     The simple, low-tech idea, was developed by researchers at Nottingham University.
     They used banana skins to create briquettes that can be burned for cooking, lighting and heating.
     It could alleviate the burden of gathering firewood, the dominant energy source in many parts of the continent.
     This would help reduce deforestation, which makes a significant contribution to global climate change.

Go yellow
     In some African countries, like Rwanda, bananas are an important and versatile crop, used for food, wine and beer.
     But experts estimate that the edible fruit makes up just a small part of what the plant produces.
     "The banana skins bind other materials together really well, they act like glue" (Joel Chaney, Nottingham University)
     According to scientists, for every one tonne of bananas, there are an estimated ten tonnes of waste, made up of skins, leaves and stems.
     It was on a visit to Rwanda that Joel Chaney, a PhD student from the University of Nottingham came up with the idea of developing a low-tech approach to turn this banana waste into an efficient fuel source.
     Back in the laboratory at the University's faculty of engineering, Joel showed me how to make bananas burn.
     He first mashes a pile of rotting skins and leaves. This pulp is then mixed with saw dust, compressed and dried to create briquettes that ignite readily and throw out a steady heat, ideal for cooking.


The banana mixture dries into briquettes which can be burned on a stove

     "We can then either form the material into a ball by hand, or use a press to squeeze the materials together and squeeze the liquid out.
     "Once we've pressed them we can lay the briquettes outside in the sun, and within about two weeks we have some dried fuel."
     The emphasis of the project has been on developing a simple technology that can be used in developing countries without the need for a large financial outlay.
     Over the years there have been many attempts to develop new stoves and fuel sources in Africa that have failed because they were too expensive or did not take on board local needs.
     "These briquettes are made by hand, we haven't used any mechanical equipment at all" (Mike Clifford, Nottingham University)
     Mike Clifford is associate professor in the department of engineering at Nottingham. Standing around a stove in the laboratory that's using banana briquettes to boil water, he says he is really pleased with the project.
     "This is working really well. These briquettes we've made by hand, we haven't used any mechanical equipment at all. No technology and we've had a really good result," he says.
     "We're starting from very basic problems and we are making the solutions as simple and accessible as possible to the people that need them.
     "It's almost seen as a new colonialism, imposing solutions on people in developing countries, we are very keen not to do that."

Saving firewood
     The scientists believe that banana fuel might help reduce dependence on wood as an energy source across Africa.

The briquettes are easily made, no machinery is required

     In some of the continent's biggest banana-producing countries like Rwanda, Tanzania and Burundi, more than 80% of current energy needs are met from burning wood.
     This has a very damaging impact on the environment leading to deforestation which contributes to climate change. Gathering wood for fuel is also a time consuming job, mainly done by women.
     "In some areas wood fuel is getting depleted and you are getting deforestation. Women sometimes have to walk over six hours a day to get firewood," says Joel Chaney.
     "This is a way to use waste from crops like bananas, to make them burn in a better way because loose residue most often just burns too rapidly.
     "Imagine just putting some straw onto your fire at home. It just goes up in flames, you can't cook food over it, while the briquettes provide a way to cook food in a much better way."
     The Nottingham researchers say their low-tech approach is a small step along the way of meeting the millennium goals and helping people out of poverty.
     They say that they are happy to give the idea away for free and are encouraging people who want to use the idea to get in touch.