PURPOSE: To readily recover an inferior heat source as electric power directly by generating effective concentration difference between an anolyte and a catholyte using inferior heat sources of relatively low temperature such as hot waste water, solar heat, especially by atacking many entropy cells which generate electric power by change of entropy.

CONSTITUTION: A cell system is so-called a typical cancentration cell which concentrates either one of liquid of both electrode chambers by utilizing hot waste heat and gives concentration difference, and when cation gives electromotive force, concentrated liquid becomes a cathode. Water pressure difference between a concentration chamber and a dilution chamber is kept low and then air is supplied with a blower 12. If the concentration chamber is warmed by hot waste water, the moisture of the concentration chamber is evaporated to concentrate the liquid. This damped air is sent through a pipe 10 to the dilution chamber, and the moisture is condensed to dilute the liquid. The dried air reaches the concentration chamber 8 through a pipe 11 with blower 12, and after that the same process is repeated.