Interesting site, and one that brings up good points. However, tidal friction as a means of energy production generates far less energy than solar radiation does. While environments such as exist on Europa and you theorize exist in dark nebulas are ideal for the existance of simple life forms, it would be difficult to get levels of energy required to support higher life forms. I'm not saying that it couldn't happen, but I am saying that it far more likely that intelligent life would be found on an environment such as the Earth rather than in the cores of Kupier Belt-like objects found in a dark nebula.