Nuclear energy generated during the nuclear fission reaction can become a renewable energy source only if we find a nuclear fuel that can be used in the nuclear reactors and represents an abundant not a finite resource.
Another disadvantage that comes with the nuclear fission reaction using uranium as nuclear fuel is the nuclear waste generated, which is very dangerous for any living being and the environment.
Disposing nuclear waste is not an easy task, it is actually a pretty complex and expensive activity involving a secured transportation system and the construction of a hermetically sealed structure that will be heavily guarded.
Thorium, which is a radioactive chemical element that can be used as nuclear fuel in the nuclear reactors to generate clean energy during the nuclear fission reaction releases less nuclear waste than uranium, so is considered a cleaner nuclear fuel.
However, even if thorium is a cleaner and a more abundant resource than uranium, it is still a finite resource, so the clean energy generated by thorium is not renewable.
To make the nuclear energy renewable we need to use a nuclear fuel that is very abundant here on Earth and in the universe.
Hydrogen is used by the Sun to generate energy, heat and light during the nuclear fusion reaction that takes place every second inside our star.
Hydrogen is a very abundant element in the known universe, so the nuclear energy generated by the nuclear fusion reaction that uses hydrogen as nuclear fuel is considered a renewable energy source.
However, humanity cannot control the nuclear fusion reaction yet, so the opportunity to generated unlimited clean energy is pretty far.
ITER (International Thermonuclear Experimental Reactor) is an international project sponsored by countries such as the U.S., the EU, Japan, China, Russia, Korea, and India, and aims to build an experimental thermonuclear reactor in Southern France to host the nuclear fusion reaction and generate unlimited amounts of clean power.
U.S. scientists are also working to bring nuclear fusion closer to our time, but because the nuclear fusion reaction is an exceptionally complex process that involves non-linear phenomena the work at the project is slow and difficult.
The human society of today, needs to further evolve to master the nuclear fusion reaction, because the process is so complex that even the best computing resources of today are not fast enough to safely control this amazing nuclear reaction that can generate unlimited amounts of clean power for us.
Scientists estimate that nuclear fusion will become available by 2050, which means that the use of fossil fuels for energy generation could be ended at the middle of this century.
It seems that we need to wait at least three more decades to see the end of the fossil fuel era and the beginning of a new era of unlimited clean power generated by the nuclear fusion reaction.