Lauren's class took a "sustainability tour" at an eco resort not far from us, and we learned how green waste from their kitchen is collected in a system that captures the methane gas it produces. The gas is converted into fuel for cooking, and the remaining compost is used as fertilizer for crops grown on-site. Cooking oils are recycled and used to create dish soap, body washes, and shampoos. It was low tech and ingenious, like so many things we've seen in Costa Rica.