The world needs a new source of energy, an unspillable source.

If Tesla discovered unlimited free energy 100 years ago, why hasn’t anybody else discovered it?

I keep hearing this conspiracy theory about how Tesla discovered unlimited free energy, but there is a conspiracy to hide it. My question, with 100 years of technological progress and millions of electrical engineers in the world working with equipment that would make Tesla’s look like a slide rule in comparison to a supercomputer, why hasn’t somebody rediscovered whatever Tesla discovered?