My study of parabolas is a bit rusty anon, but mostly those mirrors can only direct all of their energy to a single point in a single spot called the focus (the top of tower filled with salt). The mirrors only transfer reflected heat energy from the sun (as far as this anon knows). The tower would have to use that heat to power a generator of some sort converting the energy into a different form then re-emitting it out in to space from the tip of the tower.
Guess I just don't see that being the case. Cool concept though.