As the world becomes more aware of the risks of climate change and the importance of sustainable energy sources, individuals and communities are increasingly taking measures to reduce their carbon footprint. Some are building "passive homes", to take advantage of natural sun and wind patterns, while others are installing solar panels or windmills, to power their homes. But never before has there been an entire "green" city - one that relies solely on renewable energy sources and smart design elements, to eliminate its carbon footprint.