The Donnan-charged Capacitive Mixing principle
Here the figure shows the principal lay-out of the Donnan charging process. The principal difference with the EcCM process is that the particle has a coating, or membrane, that is either selective for anions or cations. It is important to note that this implies as shown in figure A that in sea water the particles will be spontaneously loaded with ions of one kind, dependent on the type of membrane (either cation-selective, or anion-selective). This generates an electron flow from the chloride-adsorbing particle to the sodium-adsorbing particle. Electrical energy is generated in this process because the membranes induce a potential difference between the particle, namely the combination of the two so-called “Donnan potentials” that build up across each membrane. When the charged particles are brought to the fresh water solution, the reverse process takes place (figure B).
Principle of energy generation via the Donnan-charged capacitive mixing process. The A picture shows the Donnan charging process in sea water, while the B picture shows the discharge process. In both cases energy is generated.
As the ions will now pass to the less saline fresh water, the electron flow is reversed and energy can be harnessed again. After discharge, the particle can be charged again in sea water and the energy generation process starts again.