  It is shown that a heat energy can be transformed in an electric energy of
direct current by the use of an inhomogeneous superconducting ring. This
trasformation is possible both at an iterative change of temperature and at an
unaltered temperature. In the first case the ring is a classical heat engine
with a maximum efficiency in the Carno cycle. The second case contradicts to
the second thermodynamic law formulated in the middle of last century.
Nevertheless this result is correct because the thermal fluctuation is an
opposite (relatively of the second thermodynamic law) consequence of the law of
entropy increase. In order to introduce some order into the chaotic energy of
the thermal fluctuations a preferential direction should exist. Such
preferential direction of superconducting electron motion exists in a ring if a
magnetic flux is not divisible by the flux quantum.
