The future of energy: Energy prospects for a budding inter-planetary civilization

The only prospect for the long-term survival of humankind is space colonization: The establishment of permanent and self-sustaining human habitats beyond Earth. One necessary condition for space colonization is energy. In order to successfully colonize space, future generations will have to have suitable sources of energy at their disposal. In this discussion paper, existing as well as possible future energy sources are analyzed in terms of their utility for space colonization. The conclusion is sobering: Among existing energy sources, Solar power and nuclear fission are most promising. However, without the (rapid) development of space-based Solar power and nuclear fusion technologies, humankind might not be able to sustain extraterrestrial habitats - humankind might go extinct if we do not develop new sources of energy quickly enough. This existential energy challenge is proposed as a novel and general explanation for the Fermi paradox (the apparent absence of technologically advanced intelligence in our galaxy other than humankind).