We proposed a concept and calculated an efficiency of the electrochemical cycle of converting the low-grade heat with the temperature difference of 10-80 degrees C into electricity. The cycle could be divided into two stages: the creation of the concentration difference by the crystalline hydrate melting at the high temperature or the crystallization at the low temperature and the electricity generation in the concentration galvanic cell. The calculations prove that the efficiency of the converting heat into the electricity could reach up to 20-35% of the Carnot cycle efficiency. (C) 2018 Elsevier Ltd. All rights reserved.