  In this paper, we calculate energy required to copy one bit of useful
information in the presence of thermal noise. For this purpose, we consider a
quantum system capable of storing one bit of classical information, which is
initially in a mixed state corresponding to temperature T. We calculate how
many of these systems must be used to store useful information and control bits
protecting the content against transmission errors. Finally, we analyze how
adding these extra bits changes the total energy consumed during the copying.
