Thanks for the comments guys. The 40 hours probably is a result of me having one to many reflective surfaces in the scene in combination with using mental ray. A good lesson for the future.

Now first of all the camera is supposed to move slowly. As this video was supposed to be used at a presention I had to have enough time to rather quickly go over the various aspects of the fan. Also the first six seconds or so are the same 37 frames repeated five times. As I was prepared for a somewhat long render time (though not as long as 40h) I had to be economic.

2nd I suppose the blades should've been tilted a bit to really work as a real fan, I simply forgot to do that.

Finally the ball in the middle is the container holding the essence that is spread through the wings. It was designed to blend in with the rest and look a bit stylish at the same time. The five things around it are spotlights that can be aimed as you like.

Again thanks for the comments and if anyone has more to say please do.