KOULIKORO, Mali — When Suleiman Diarra Banani’s brother said that the poisonous black seeds dropping from the seemingly worthless weed that had grown around his family farm for decades could be used to run a generator, or even a car, Mr. Banani did not believe him. When he suggested that they intersperse the plant, until now used as a natural fence between rows of their regular crops — edible millet, peanuts, corn and beans — he thought his older brother, Dadjo, was crazy.

Jatropha grows in places like Koulikoro with little rainfall.

“I thought it was a plant for old ladies to make soap,” he said.

But now that a plant called jatropha is being hailed by scientists and policy makers as a potentially ideal source of biofuel, a plant that can grow in marginal soil or beside food crops, that does not require a lot of fertilizer and yields many times as much biofuel per acre planted as corn and many other potential biofuels ... ...more.