Capacitive technology for energy extraction from chemical potential differences.

摘要: This thesis introduces the principle of Capacitive energy extraction based on Donnan Potential (CDP) to exploit salinity gradients. It also shows fundamental characterization and improvements CDP. An alternative application this technology aimed at thermal gradients was tested. Chapter 2 initial tests. The entropy increase mixing two solutions different salt concentrations can be harnessed generate electrical energy. Worldwide, potential resource, controlled river seawater, is enormous, but existing conversion technologies are still complex expensive. Here we present a small-scale device that directly generates power from sequential flow fresh saline water, without need auxiliary processes or converters. consists sandwich porous “supercapacitor” electrodes, ion-exchange membranes, spacer further miniaturized scaled-out. Our results demonstrate alternating water through capacitive cell allows direct autogeneration voltage current consequently leads generation. Theoretical calculations aid in providing directions for optimization properties membranes electrodes. In 3, traditional electrochemical techniques (galvanostatic charge–discharge cyclic voltammetry) were used investigate intrinsic open system. study demonstrates feasibility characterize behavior low concentration (0.5 M). Presence as well possibility having electrolyte flowing investigated. studied cell, presence showed limitation by anion exchange membrane densities no effect high densities. rate did not influence capacitance system either. 4uses again stack eight cells coupled parallel viability technology. average density 0.055W/m2was obtained during peak cycles, though reasonable suggests an expectation 0.26W/m2at 6.2 A/m2. found 83 ± 8% theoretical driving operating process. By studying polarization curves charging discharging it optimizing feed fluid currently among most beneficial paths make CDP viable difference source. Another route increasing efficiency lowering internal ohmic resistances design modifications. A modification proposed 5, approaching electrodes geometry has relevant impact resistance overall performance work, first effort use wire-shaped its suitability improving Analytical evaluation measurements confirm strong nonlinear decrease distances between smaller than 3 mm. We get more per material invested when compared flat plate designs. These findings show advantages development into mature Alternatively, 6, new producing electricity temperature differences using affordable assembly combining ion supercapacitor carbon involves isolated salty solutions, with equal temperatures. operation alternately exposure these electrolytes. thermomembrane acts force ionic adsorption/desorption cycles simple interesting exploiting waste heat. When volumes have temperatures, possible immerse pair (anode cathode) one adsorption. electric then generated external circuit achieve electro neutrality. After saturation, same immersed T volume ions desorb released volume, leading reverse step. experiments prove dependence gradient extraction. Finally, 7discusses losses identified faced throughout thesis. summarize encountered major contributions hindering give suggestions develop