Tesla discovered almost immediately that beaming his power source was unsafe to anyone or any animal which encounters the beam - a bit like focused microwaves today, which Tesla generally predicted.
Tesla's prediction of the Solar Wind and Cosmic Ray effects was generally correct, but there remains no safe way of harnessing such a widely distributed power source, and Tesla never came up with a practical solution. Tesla was a capable documentarian. If you doubt that he had not found a practical solution, just read everything about Tesla and tell me if you see it there.
Unfortunately Tesla did not foresee that high enough voltages produce X-Rays, and he exposed himself to very high dosages by remaining near high voltage arc discharges. Roentgen had written about X-Rays in 1895, four years before Tesla set up his Colorado laboratory, so in spite of his great intellect, he failed to read Roentgen.