The Idea: Local food in growing cities

Stage: Buzz words and pretty drawings

Single-story, high-tech greenhouses save significant amounts of water and increase productivity. So why not stack them up and makes cities self-sufficient? The idea for vertical farms came from an infectious disease ecologist, Dickson Despommier, who turned his knowledge of parasites into a way of looking at cities. "Instead of the city behaving like a parasite, it should be a symbiant," Despommier says. "The future city has to take a big lesson from nature and start behaving like an ecosystem." By that, he means zero-waste cities: Even the idea of waste is anathema to a working ecosystem. So Despommier envisions skyscrapers of the future producing the majority of food consumed by citizens, with brown water and food compost used for farming. "City life," says Despommier, "demands city food."