“…where ZT → ∞ corresponds to the Carnot efficiency. Today, ZT 3 for Bi-doped Pb-SeTe/PbTe [3], but commercial TE materials usually have ZT 1. This means, that near room temperature, at T h = 300 K, and for a temperature interval of 20 K (i.e., T c = 280 K), COP max cannot be higher than 31% of the Carnot efficiency with the most advanced TE materials, and with commercial Peltier cells COP max 14% of Carnot's COP at most.…”