We have developed a new thermoelectric power-generating module composed of 72 pieces of n-type Ba8Al18Si28 clathrate elements made by arc melting. The Seebeck coefficient, specific electric resistance and thermal conductivity of Ba8Al18Si 28 clathrate were 250 μV/K, 1.9 mΩcm and 3.1 W/mK at 500°C, respectively, and the thermoelectric figure of merit (ZT) was 0.8. The new thermoelectric module was constructed using only n-type thermoelectric elements connected in series with hook-shaped electrodes. The open-circuit voltage of the module was 1.8 V at the hot-side temperature of 500°C. The maximum electric power was 0.24 W. The module was successfully used to charge lithium-ion batteries for mobile phones.