TechFreep recently pointed to a company called Infinia which is combining parabolic solar dishes with Sterling motors to convert light into energy more efficiently than conventional photovoltaic cells.
Now, if you use these Solar Sterling engines as solar power satellites and combine this with a superstructure that uses space elevators to raise water from the ocean (which thereby can be broken down into hydrogen/oxygen), you could potentially design a reversed Niven ring that floats in geosynchronous orbit around the earth.
One of these days I’ll put together an illustration of what I have conjured up, I’m sure someone has thought it up before.