  It is widely assumed that the observed universe is accelerating due to the
existence of a new fluid component called dark energy. In this article, the
thermodynamics consequences of a nonzero chemical potential on the dark energy
component is discussed with special emphasis to the phantom fluid case. It is
found that if the dark energy fluid is endowed with a negative chemical
potential, the phantom field hypothesis becomes thermodynamically consistent
with no need of negative temperatures as recently assumed in the literature.
