  We develop here a mechanism that, without making use of a cosmological
constant, reproduces an accelerating universe. This is done by taking into
account Casimir vacuum energy density, assuming that the underlying theory
allows a maximum momentum, that turns out to be the leading contribution term
to Einstein equations in a large expanding FRW universe. As stated in numerous
quantum gravity studies, we postulate that maximum momentum is related to the
existence of the Planck length as a fundamental length. This insight, together
with the assumption of a Planck scale correction to the energy/momentum
dispersion-relation on a FRW background, is used here to calculate Casimir
vacuum energy. We show that, under these hypothesis, an accelerated universe
expansion is obtained. As last step we analyze the compatibility of the
resulting model with experimental data, writing down the equation of state for
Casimir energy and pressure and observing that this equation of state belongs
to a class of models that naturally fits cosmological observations. We
emphasize that our result relies, once a fundamental length is introduced in
Casimir effect, just on general arguments thus it is independent on an explicit
form of the energy-momentum dispersion relation.
