Charging-free electrochemical system for harvesting low-grade thermal energy
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139,
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305,
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, and
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305,, Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
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. We demonstrate a charging-free TREC consisting of an inexpensive soluble Fe(CN)63-/4- 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.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
- Grant/Contract Number:
- SC0001299/DE-FG02-09ER46577; SC0001299; FG02-09ER46577; EE0005806; AC02-76SF00515
- OSTI ID:
- 1235150
- Alternate ID(s):
- OSTI ID: 1385293
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 111 Journal Issue: 48; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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