Display MoreThe problem is, the mobs would run around randomly, which will produce energy, but they won't die by this. And since they will most likely not move in the same direction, they won't move anything. The wheel with the hamster will only rotate if you have a single hamster, with two inside running in different directions the only thing you get is a funny youtube-video.
So without a bait that keeps the mobs in one direction it normally would not even produce energy at all, and the question is still if treadmills connect. So does a treadmill attached to another treadmill needs to move in the same direction? If yes, then you will have to add all movement on top of all connected treadmills, to get the direction they are moving... quite tricky.
And they only provide energy if the objects they carry aren't moving (from an outside view). Imagine again the hamster in the wheel. The wheel does only produce power if the hamster is in a fixed position and the wheel is turning. If the hamster moves along the wheel it will produce power, but it will slow down (since the hamster is not able to move the wheel in this situation). If the hamster just runs circles inside the wheel then there is no power.
So you could use the mobs to power treadmills, which are able to move items along (the items move in the opposite direction the mobs are moving). But you can't move the mobs which are standing on the treadmills.
Use water to move mobs?