Some artificial islands seem necessary. Some just are and some are excessive. And some may sustain human life in the future. Yesterday LiveScience reminded us of a promising idea that we covered earlier: creating rig-like islands that drill the oceans not for oil but for renewable energy.

At the core of each man-made island -- the brainchild of inventor Dominic Michaelis and his son and architect Alex -- are power plants that rely on ocean thermal energy conversion (OTEC). That is, they use the differences in temperatures at the depths and surface of the ocean to evaporate and condense another fluid substance, like seawater, which in turn pushes a turbine. The resulting power, they say, would be 250 megawatts (MW) -- enough to