A question for fluther's astro and quantum physicists: Is there a way to extract usable energy from quantum vacuum fluctuations?

First of all, of course, is to acknowledge that at its base state, energy can not be extracted because you can not go below the zero point of the energy level of empty space.

But, here is my question:
Would subjecting space to the intense gravitational effects of a black hole (which we might create artificially), cause a momentary density spike of these fluctuations (due to space being compressed), raising the energy level of empty space above the zero point, even if just for just a moment, so that then this small excess of energy could be harvested?