  The thermoelectric coefficient $\eta(T)$ in unconventional superconductors is
enhanced below $T_c$ by intermediate strength impurity scattering that is
intrinsically particle-hole asymmetric. We compute $\eta(T)$ for a
strong-coupling d-wave superconductor and investigate the effects of inelastic
scattering originating from electron-boson interactions. We show that $\eta(T)$
is severely suppressed at temperatures just below $T_c$ by a particle-hole
symmetric inelastic scattering rate. At lower temperatures inelastic scattering
is frozen out and $\eta(T)$ recovers and regains its large amplitude. In the
limit $T\to 0$, we have $\eta(T)\sim \eta_{0} T+{\cal O}[T^3]$, where the slope
$\eta_{0}$ contains information about the Drude plasma frequency, the details
of impurity scattering, and the change in effective mass by electron-boson
interactions. In this limit $\eta(T)$ can be used as a probe, complementary to
the universal heat and charge conductivities, in investigations of the nature
of nodal quasiparticles.
