  It is discussed how Penrose process can be used in a strange star, described
by the Hartle-Thorne metric, to extract its rotational energy. This metric has
an ergosphere region that depends only on its angular momentum. It is shown
that massive particles with negative energy can exist in this ergosphere,
exploring the conditions on the radial distance and on angular momentum for
this to occur. It is also calculated the total amount of rotational energy that
can be extracted from the strange star, and how these conditions cannot be
fulfilled by a star with regular matter.
