As we negotiate yet another pothole, Mrs. Atego laughs. First at how badly I’m driving along the pitted road outside Nairobi, and second at the fact that I want to visit her farm at all. “Why do you want to see my jatropha?” she asks. “You’re going to see the worst.” When we finally arrive, I gaze over a field dotted with stunted seedlings. They only grew a few inches in their first year, she explains. It is a far cry from the promise of a harvestable crop after nine months. Like other Kenyan farmers, Mrs. Atego has experienced both optimism and disappointment over this biofuel crop. ...