The power density wouldn't be near that bad. From geostationary, the footprint would be several square miles, and birds could fly through the beam without harm.

The power density wouldn't be near that bad. From geostationary, the footprint would be several square miles, and birds could fly through the beam without harm. Even getting that much focus from phased-array transmitters would require a reference signal from the ground, so if the beam went astray it would spread out much more. Despite the low power density the ground station would still be cheap, since it'd mostly be wire antenna. (Source: the book The Case for Space Solar Power)