The government is finally getting serious about space based solar. The government of China, that is. The U.S. government (Jimmy Carter, NASA) was serious about it back in the 1970s as I recall (actually, I don’t recall because I was an infant, but I have since read). Our cynical government stopped looking into shortly thereafter and the public imagination withered and died. The interesting thing is that the Earth is in the path of only an infinitessimal portion of the sun’s energy. However much energy we need and are able to harness with our technology, we should be able to intercept it and beam it back, without depriving anyone or any natural ecosystem of their fair share. Utlimately, the limit would probably be how to deal with waste heat rather than any upper limit on how much energy we could intercept and beam back to Earth.