The zero-point energy of the vacuum is converted into classical mechanical energy in the Lab. You can see the proof, if you follow the links below.

The development should now be continued until a free and inexhaustible energy-source will be possible free from any environmental pollution.

_{By the way: I published all my scientific results for the free benefit of everybody. I did not patent anything. If everybody would do like this, there would not be any fighting for energy any further.}