  We propose a hydrodynamic model to study the thermotransport properties of
semiconductor electrons. From the semiclassical Boltzmann equation a set of
balance equations is built for the relevant fields. The electron density, the
electron energy density, the electric current density and the heat flux density
are considered as the basic fields of direct transport and cross effect fluxes.
The kinetic relaxation times of the production terms are calculated by
considering the electron-acoustic phonon interaction as the leading microscopic
scattering process. To justify the long time thermalization regime, the Onsager
symmetry relations are proved, both on the completely degenerate and non
degenerate limits.
