Imagine stepping 50 years into the future and finding smart cities designed to be totally sustainable. Renewable energy is our primary power source; space-based solar power provides energy 24 hours a day; everything is recycled; and you have your own individualized pods that run on maglev trains using little or no energy. You can also ride an electric flying vehicle! Traffic jams are a thing of the past. This isn’t science fiction. Engineers are making plans for a sustainable world right now.