ZERI (Zero Emissions Research and Initiatives), established a coffee farm system, starting in the coffee growing region of western Colombia. The system mimics a closed-loop ecosystem and follows Life's Principles. Coffee consumed by the coffee drinker represents only 0.2% of the biomass generated by the coffee plantation. The remaining 99.8% of the coffee plant and bean is considered waste. ZERI wanted to find a way to make use of that waste to generate additional income for the coffee farmers. But they also sought to create more of a closed-loop ecosystem, in which rather than having waste products that end up in rivers or landfills, or are burned, those wastes are themselves used within the system.The key to the success of this system was research showing that shiitake mushrooms grow very well in a readily available mixture of local "waste" that includes wet coffee pulp, sawdust from coffee bush stems, and coffee hulls, and the mushrooms could be sold domestically. Up to 60 pounds of shiitake can be produced on 100 pounds of coffee waste. There is a local market for shiitake mushrooms, which is another advantage of choosing that species over oyster or reishi mushrooms.Organic residues left after the coffee harvest are fed to cattle and pigs, or are broken down by earthworms, which in turn serve as feed for chickens. Manure from the cattle and pigs is converted using a digester into biogas and slurry. The biogas provides heat for the mushroom farming, and the slurry serves as organic fertilizer for vegetable gardens and coffee bushes. This type of closed-loop ecosystem is now applied to beer breweries.