Capacitive mixing power production from salinity gradient energy enhanced through exoelectrogen-generated ionic currents

Hatzell, Marta C.; Cusick, Roland D.; Logan, Bruce E.

Capacitive mixing power production from salinity gradient energy enhanced through exoelectrogen-generated ionic currents

Type

Article

Authors

Hatzell, Marta C.
Cusick, Roland D.
Logan, Bruce E.

KAUST Grant Number

KUS-I1-003-13

Date

2014

Abstract

Several approaches to generate electrical power directly from salinity gradient energy using capacitive electrodes have recently been developed, but power densities have remained low. By immersing the capacitive electrodes in ionic fields generated by exoelectrogenic microorganisms in bioelectrochemical reactors, we found that energy capture using synthetic river and seawater could be increased ∼65 times, and power generation ∼46 times. Favorable electrochemical reactions due to microbial oxidation of organic matter, coupled to oxygen reduction at the cathode, created an ionic flow field that enabled more effective passive charging of the capacitive electrodes and higher energy capture. This ionic-based approach is not limited to the use of river water-seawater solutions. It can also be applied in industrial settings, as demonstrated using thermolytic solutions that can be used to capture waste heat energy as salinity gradient energy. Forced charging of the capacitive electrodes, using energy generated by the bioelectrochemical system and a thermolytic solution, further increased the maximum power density to 7 W m -2 (capacitive electrode). © 2014 The Royal Society of Chemistry.

Citation

Hatzell MC, Cusick RD, Logan BE (2014) Capacitive mixing power production from salinity gradient energy enhanced through exoelectrogen-generated ionic currents. Energy Environ Sci 7: 1159. Available: http://dx.doi.org/10.1039/c3ee43823f.

Acknowledgements

This research was supported by the National Science Foundation Graduate Research Fellowship Program (Grant No. DGE1255832 to M.C.H.), and a grant from the King Abdullah University of Science and Technology (KAUST) (Award KUS-I1-003-13). We would like to acknowledge Guang Chen for synthesizing the AEM coating and Kelsey B. Hatzell for constructing and characterizing the capacitive electrodes.