His Rifters books had some interesting tech in them that I want to see in the real world (for positive uses): dirigibles using vaccuum for buoancy rather than hydrogen or helium, and abiotic food production ala the "Calvin Cyclers" he has in the book. Abiotic food production using only minerals, water, and air as inputs would be tremendously helpful for space colonization and also for scarcity scenarios on earth, like living in the arctic, at sea, or in the desert.