The first single-family seastead produced 60 gallons of fresh water every day, powered by just a few solar panels, and the price of solar just keeps dropping. There are many existing technologies to make drinking water from seawater given a source of energy such as electricity or heat. Energy can be generated in a variety of ways depending on the location. A combination of biofuel, wind, solar, wave and marine current energy generation coupled with storage is already viable and cost effective at smaller scales. Seasteads can grow fresh produce in vertical farms and raise seafood using aquaculture. Excess food and energy can be traded with the host nation or even exported.
See our videos Live in Balance with Nature and Feed The Hungry.