Charging-free electrochemical system for harvesting low-grade thermal energy
Author(s)Yang, Yuan; Lee, Seok Woo; Ghasemi, Hadi; Loomis III, Robert James; Li, Xiaobo; Kraemer, Daniel; Zheng, Guangyuan; Cui, Yi; Chen, Gang; ... Show more Show less
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Efficient and low-cost systems are needed to harvest the tremendous amount of energy stored in low-grade heat sources (<100 °C). Thermally regenerative electrochemical cycle (TREC) is an attractive approach which uses the temperature dependence of electrochemical cell voltage to construct a thermodynamic cycle for direct heat-to-electricity conversion. By varying temperature, an electrochemical cell is charged at a lower voltage than discharge, converting thermal energy to electricity. Most TREC systems still require external electricity for charging, which complicates system designs and limits their applications. Here, we demonstrate a charging-free TREC consisting of an inexpensive soluble Fe(CN)[3−/4− over 6] redox pair and solid Prussian blue particles as active materials for the two electrodes. In this system, the spontaneous directions of the full-cell reaction are opposite at low and high temperatures. Therefore, the two electrochemical processes at both low and high temperatures in a cycle are discharge. Heat-to-electricity conversion efficiency of 2.0% can be reached for the TREC operating between 20 and 60 °C. This charging-free TREC system may have potential application for harvesting low-grade heat from the environment, especially in remote areas.
DepartmentMassachusetts Institute of Technology. Department of Mechanical Engineering
Proceedings of the National Academy of Sciences
National Academy of Sciences (U.S.)
Yang, Yuan, Seok Woo Lee, Hadi Ghasemi, James Loomis, Xiaobo Li, Daniel Kraemer, Guangyuan Zheng, Yi Cui, and Gang Chen. “Charging-Free Electrochemical System for Harvesting Low-Grade Thermal Energy.” Proceedings of the National Academy of Sciences 111, no. 48 (November 17, 2014): 17011–17016.
Final published version