Ummm... if you have infinite power to pull carbon from the atmosphere, don't you also have infinite power to launch radioactive nuclear waste at the sun using mass-drivers? Sounds like that would be a lot more efficient than what you're proposing, too, since it's all fairly concentrated.

The whole infinite power from space argument seems problematic. Even assuming you just meant "a large, globally significant amount of power", I'm guessing that the inverse-square law and heat buildup would sink the idea. I can only imagine the dead zone surrounding the location where we beam petawatts of radiation down from orbit. It would make our worst ecological disasters look like a joke in comparison.