Energy Extraction and Water Treatment in One System: the Idea of Using a Desalination Battery in a Cooling Tower

The use of sodium manganese oxide as an intercalation electrode for water treatment was recently explored, and referred to as a “desalination battery” and “hybrid capacitive deionization”. Here, we examine the feasibility of using such a desalination battery,
comprising crystalline Na4Mn9O18 as the cathode and Ag/AgCl/Cl- electrode as the anode, to extract energy from low-grade waste heat sources. Sodium manganese oxide electrode’s material was produced via a solid-state synthesis. Electrodes were produced by spray-coated
onto graphite foils, and showed a temperature dependence of the electrode potential, namely, E / T , of -0.63mV/K (whereas, the Ag/AgCl/Cl- mesh electrode showed much lower temperature dependence, < 0.1mV/K). In order to demonstrate ion-removal capabilities
together with the feasibility of thermal-energy conversion, a flow battery system was constructed. Thermally regenerative electrochemical cycles (TREC) were constructed for the flow battery cell. The thermal energy conversion, in this particular system, was shown to be
feasible at relatively low C-rate (C/19) with temperatures varying between 30 °C and 70 °C.