[imiric]

> Robots will run on batteries or some other form of power - there is no way anyone is close to building robots that can eat break down food and use it for energy and repair.

Couldn't we sidestep the complexity of digestion and just get energy from the Sun? With improvements in solar cells and battery technology, we wouldn't need to engineer something as complex as extracting nutrients from food.

I don't think we'd want to replicate biological systems in robots. Digestion and procreation happen at the cellular level, and achieving that with technology is indeed hard sci-fi. Autonomous humanoid robots can exist and be useful for us without this level of sophistication. Though once this happens AI itself will be capable of self-improvement, so we can leave it up to them how they want to improve. I, for one, welcome our new robot overlords. :)