Despite the mainstream physicists pretend, that everything around us is driven with thermodynamical laws and spontaneously increasing entropy (which defines so-called entropic time arrow), in real world around us we can find many examples of entropic time arrow violation. In my theory the overunity arises during thermalization of negentropic phenomena, like the overheating or oversaturation, which violate the entropic time arrow by formation of metastable state. The magnetization of ferromagnetics (especially these ones in form of thin needles or whiskers, where ferromagnetic domains have no place for reorientation) is one example of metastable state. The formation of metastable undercooled atomic hydrogen from electric arc or NMR excitation of carbon or iron nuclei in magnetic field are another example of such negentropic phenomena, the thermalization of which can be assisted with vacuum fluctuations.
In my understanding this principle of energy production isn't even very new one, because the energy released during nuclear fusion or fission also utilizes the metastable states of matter remaining during non-equilibrial explosions of stars into supernovae. The atom nuclei which we are living with want to fuse or split and only small energy input (introduced during implosion of nuclear bomb for example) is able to release much higher amount of energy on demand by making it more reversible. The general way how to make metastable system reversible is to establish/enforce lower or higher-dimensional routes for energy sharing and thermalization in it.