These tools are contributing to the growing science of cities. This initiative envisions the use of circular economy techniques to link an urban extension to existing settlements. The initiative aims to incen-tivize ideas for decentralized, closed-loop models of spatial planning and peri-urban service provision that replace fossil energy with renewables, derive new water, biogas, and fertilizer from wastewater, and produce food and biofuel with recycled inputs, all co-generated at near net-zero waste. Each RENEWW Zone would offer, within walking or cycling distance, a green space for community recreation, recycling and sanitation services, as well as a place to purchase fresh food, recycled goods, biofuels and safe drinking water.