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 solar 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.