  Recently colossal Seebeck coefficient ($S$) has found in the several
thermoelectric (TE) materials. We present colossal $S$ and large thermal
electron motivate force (EMF) reproduced by space charge (SC) model,
introducing multi-Debye lengths within grain boundaries (GBs) of TE materials
with phonon drag (PD) effect accompanying with electron by electron-phonon
interaction. In addition to $S$, the polarity reversal was also reproduced by
transfer process with inner bias around SP generated from thermal EMF. Colossal
$S$ and EMF for TE material were reproduced by inner SC model as a functions of
averaged multi-Debye length within GBs.
