  In this article, we show fundamentals and recent advances on the transverse
thermoelectric generation, in which a thermopower is generated in the direction
perpendicular to an applied temperature gradient. Transverse thermoelectric
generation is one of the central topics in condensed matter physics, and can be
a breakthrough approach to solve long-standing technological problems with
contact resistances in thermoelectric generators. We review here the six
currently known driving mechanisms: the ordinary Nernst effect, the anomalous
Nernst effect, goniopolar materials, the spin Seebeck effect, Seebeck-driven
transverse thermoelectric generation, and ($p \times n$)-type multilayers. This
article summarizes the principles and functionalities of these transverse
thermoelectric effects and discusses their potential as "Future energy".
