  We present a study of the thermopower $S$ and the dimensionless figure of
merit $ZT$ in molecules sandwiched between gold electrodes. We show that for
molecules with side groups, the shape of the transmission coefficient can be
dramatically modified by Fano resonances near the Fermi energy, which can be
tuned to produce huge increases in $S$ and $ZT$. This shows that molecules
exhibiting Fano resonances have a high efficiency of thermoelectric cooling
which is not present for conventional un-gated molecules with only delocalized
states along their backbone.
