  The holographic principle is applied to a flat Friedmann-Robertson-Walker
space-time dominated by dark energy when this is due to the presence of a
k-essence scalar field, both for dark energy and phantom scenarios. In this
framework, a geometrical covariant approach permits the construction of
holographic hypersurfaces. The resulting covariant preferred screens, both for
phantom and non-phantom regions, are then compared with those obtained by using
the holographic dark energy model with the future event horizon as the infrared
cut-off. In the phantom case, one of the two obtained holographic screens is
placed on the big rip hypersurface, both for the covariant holographic
formalism and the holographic phantom model. It is also analysed whether this
covariant formalism allows a mathematically consistent formulation of
fundamental theories based on the existence of a S-matrix at infinite
distances.
