  The well-known hierarchy between the Planck scale (~10^{19}GeV) and the TeV
scale, namely a ratio of ~10^{16} between the two, is coincidentally repeated
in a inverted order between the TeV scale and the dark energy scale at
\~10^{-3}eV implied by the observations. We argue that this is not a numerical
coincidence. The same brane-world setups to address the first hierarchy problem
may also in principle address this second hierarchy issue. Specifically, we
consider supersymmetry in the bulk and its breaking on the brane and resort to
the Casimir energy induced by the bulk graviton-gravitino mass-shift on the
brane as the dark energy. For the ADD model we found that our notion is
sensible only if the number of extra dimension n=2. We extend our study to the
Randall-Sundrum model. Invoking the chirality-flip on the boundaries for
SUSY-breaking, the zero-mode gravitino contribution to the Casimir energy does
give rise to the double hierarchy. Unfortunately since the higher Kaluza-Klein
modes acquire relative mass-shifts at the TeV level, the zero-mode contribution
to Casimir energy is overshadowed.
