The central issue in zero-point energy extraction is that space is not an empty vacuum. Mainstream physics attempts to disguise this fact by altering the meaning of displacement current from the original meaning. In his 1861 paper "On Physical Lines of Force", James Clerk-Maxwell introduced the novel concept of displacement current as well as identifying Faraday's electrotonic state with electromagnetic momentum. The latter now appears in modern textbooks as a vector, usually denoted by the symbol A, but without any physical meaning whatsoever. And likewise displacement current is introduced in modern textbooks devoid of the physical meaning that Maxwell was hinting at.
It is now shown that the magnetic vector potential A and Maxwell's displacement current are one and the same thing, and that they refer to the fine-grained circulating electric currents, circulating at the sped of light, which fill all of space. For the details see,