We consider the thermodynamic properties of systems in contact with an
information source and focus on the consequences of energetic cost associated
with the exchange of information. To this end we introduce the model of a
thermal tape and derive a general bound for the efficiency of work extraction
for systems in contact with such a tape. Depending on the perspective, the
correlations between system and tape may either increase or reduce the
efficiency of the device. We illustrate our general results with two exactly
solvable models, one being an autonomous system, the other one involving
measurement and feedback. We also define an ideal tape limit in which our
findings reduce to known results.Comment: 6 pages, 6 figure
