Breeder Reactors

Breeder reactors are a type of nuclear reactor that produce more fissile materials than they consume. They are designed to extend the nuclear fuel supply for the generation of electricity. If you use breeder reactors, there is enough nuclear fuel on earth to power all of humanity (electricity + heat + transportation + industry) for ~4 billion years, thereby making it literally as renewable as the sun-derived renewables (wind/solar/hydro). In other words, the sun will run out of its finite but huge nuclear fusion fuel around the same time. The concerns about nuclear weapons proliferation have been one large impediment to creating breeders.