The tower was powered by hydro electric . Hydro electric is the only renewable scorce aside from neuclear that yields sufficient results based inthe relative cost and area it takes up . Wind and solar would need stations larger than Australia to power North America so it is very space inefficient
Formerland1: It was also hypothesized that Tesla could get electricity from the ionosphere for the tower as well. It is unknown if it would actually work or not, and it is unclear if Tesla intended on trying it or not, but if it would work it would have been extremely efficient.