What would harnessing of gravitational waves look like?
The mass of fundamental particles, like the proton or electron is very very small in comparison to the charge. This means that the motion of electrons in atoms can produce significant amounts of high frequency electromagnetic radiation. 

Quantum effects stop electrons from falling into the protons they orbit. 

To produce and control gravitational radiation in significant amounts you would need something very small, but very massive: a microscopic pair of black holes. 

Such things would be rather hard to manage. In short it is beyond any conceivable current or future technology.