No, and the smallness of the force has nothing to do with it. While it's true that there's a force between two metal objects that you could use to do some work, this doesn't get you energy for free because you had to do some work yourself in order to pull them apart in the first place.
Consider that gravity is "weak". Is it not possible that the mechanics of casimir force, which cause two objects to be pushed together from the outside, might mimic gravity which appears to be two objects attracting?
Might it be that we can't find "gravity" as an attractive force, because it is casimir forces, as repulsive forces, over several scales?
Yes, except that tidal forces are "renewable" in the sense that the energy comes from outside our eco-system. Thus if one is using such a method to "reset" the system the energy moved in to the local system is effectively free. Such energy acquired does not need an equal amount of work [from the local system] to drive as is moved in to the system.
That's the and. In short, in the same way solar energy brings energy in to the locality such a system could theoretically work thus being so down on it (as to say it will never be made to work) seems counter-logical.
So skip the complicated casimir effect energy generator and just use tidal forces or solar energy or what-have-you directly, that's the point I'm making.