Thanks to Prof. M.T. Daniels, we have a simple answer to the question: What is changing "When a free energy system works and creates the power from "nothing?"

According to Daniels, the density of the gravitation field energy near
the surface of our planet is equal to 5.74 x 10^{10} (T/m^{3})

Assume that any free energy system uses this form of energy by
means of transformation of natural curved space-time in uncurved flat space-time
in the limit.

What is the real situation? If the system creates 100 Kw of power
in load, this system decreases the natural gravitation field energy
density in that area of space-time around itself. This decrease is a function
of 1/R^{2} where R is the distance from central point of free energy
transformation. The value of this change for 100 KW power is equal to 0.001%
of natural gravitation field energy value for R=1 m and for linear function
1/R. In real case of 1/R^{2} function this change is less at the
same point.

So, the changes of natural spatial curvature in the area near the free energy machine is calculated by a similar method. It is necessary to use Daniels' density, factor of distance R at the point or calculation and the power of device.