Solar energy is a very long-term goal if you include a dyson sphere in your calculation. And even less long-term, it is not that bad for space travel as you hav

Solar energy is a very long-term goal if you include a dyson sphere in your calculation. And even less long-term, it is not that bad for space travel as you have more and especially 24h coverage without an atmosphere and a planet to block the view. Even on earth, cheap wind and solar power may be used in the near future for (more) long term storage solutions like power-to-gas etc. With 3ct per kWh as currently planned in Dubai, that is entirely feasible. Nuclear power (I am not speaking about fusion as that is still down the road) is to the contrary rather short-term as the sources for uranium etc. are somewhat limited. And it wont get cheaper anymore. On the contrary we are still detecting down-sides of nuclear energy like it was detected in recent years that around nuclear plants there are significantly less female life birth and increased child tumor rates. Not much but for still around a thousand girls for a normal power plant over its life time. Of course, coal is not better in that regard but wind and solar are or at least will be.