Man in prison uniform at the biogas digester system he helped design.

Prisoner of 22 years Gregoire Nsengiyumva, 53, talks about the biogas digester system he helped design (within the cement containers on left and right) at Rwamagana Prison in Rwamagana, Rwanda, on November, 2017. All of Rwanda's prisons use their prisoners' waste, in addition to that of cows, to fuel their kitchens via biogas. At Rwamagana, biogas is used to cook corn, and peat cooks rice and beans. Many prisoners say they can usually tell when biogas is used due to the lack of smokey flavor in food. Nearly half of all Rwandans live in poverty, relying on small-scale farming for survival without gas or electricity. With so many women and children spending hours of the day foraging for wood used for cooking and light, often damaging their eyes, lungs, the forests and atmosphere.