The
Casimir Force, which causes two very close (a few angstroms) perfectly parallel plates to be attracted to each other, may be a way of extracting zero point energy.
There are a variety of controversies about the zero point energy. In particular, quantum mechanics requires that it be extremely large, but general relativity indicates that energy produces gravitational effects so that such a large amount of energy would curve spacetime in such a way that's inconsistent with observations that indicate we live in a Minkowski spacetime. I'm not sure if someone's found a regularization scheme for the ZPE similar to the ones that solved similar problems arising in QED and QCD.