Tesla had some radical ideas on how to harness and control electricity. Many say if Edison and JP Morgan had not destroyed his work then all mankind would have free energy by now. That is why is was killed they could not make money off it. Much of what he was talking about was the same as the how cell phones work at a basic level, but at much higher voltage levels. He proved that he could push energy through the air. There were no wires so others could not make money.
Hopefully someone will come along who can rediscover his lost technology and solve the issues with the energy crisis.
Wizard: The Life and Times of Nikola Tesla : Biography of a Genius