[garbageseeker]

In the beginning you might need a governmental subsidies but when more people invest in those companies you can eliminate them. Similar when the US government invested in space program in the 1960s. When more people begin to use the fuel and profits begin to rise then the government can cut its investment. Possibly for their trouble that the government gets a percentage of the profits for its investment in research and development. Or you can form a conglomerate of companies to subsidize the development of the technology like Shell Deutschland Oil

[Mia T]

I was considering economic viability from a different angle, i.e., whether the cost in terms of fuel expended exceeds the return in terms of fuel produced.