Free energy harvesting

I've mentioned Vernor Vinge before, and I'm going to do it again (seriously, if you want to read one of the best authors of speculative fiction and technological forecasting, this is the dude). Anyway. In his book, A Deepness in the Sky, he writes about machines that resonate at the right frequencies of background radiation (sort of) to harvest free energy.

At the CES this year, it appears that RCA of all companies may get there first: