Another source of income would be the culture of blue-green algae, which, being very rich in proteins, could be a source of nutrients for food manufacture. An advantage of this culture is the fact that blue-green algae absorb carbon dioxide, the main greenhouse gas, and release oxygen with an exceptionally high efficiency. If thousands of such floating cites were built, global warming would become a thing of the past. Since this culture is very efficient, it could later also be used in space colonies as a source of food and oxygen, the two most important things to have in space.

Thus, these floating cities would not only be self-sufficient, but also will generate huge amounts of income. Marshall T. Savage calculated that such a floating city of 100 000 inhabitants would generate a net profit of over 4 billion dollars annually. This is well enough for the starting of the space colonization effort.