**Janic**, you write this amazing first sentence:

Moreover, this device is not any free energy or miraculous surunity. According to them, it would provide 12 kw / h for a consumption of 4 kw / h for the air compressor and the operating losses.

However this corresponds very exactly to the definition of overunit, since there is, at least according to the "designers" more energy at the output than at the input. No particular value of additional energy is required to satisfy the overunit condition.

Here, 4 is the unit consumed and 12 what is produced => the ratio is therefore 1/3; input / output.