Mukande Qwe, 31, lives with her husband and three children in a small hut in Kabunjwiri, rural Rwanda. The family has a small farm, where they grow beans and maize. Like all the other farmers in her village, she uses a diesel-operated pump to water her crops. “It is the only option we have,” she says while standing outside her home with her youngest son. “This pump is very heavy, and the diesel is expensive, but we can not rely on the rains alone.” Today, agriculture is the most important economic sector on the continent, providing work for over two-thirds…