The capacitive mixing procedure for energy extraction based on Double Layer Expansion (CDLE) belongs to the group of so-called CAPMIX techniques, which aim at obtaining energy from the salinity difference between fresh and sea waters. Specifically, the CDLE technique takes advantage of the voltage rise that occurs when sea water is exchanged for river water in a pair of porous electrodes which jointly behave as an electrical double layer supercapacitor. In this article, we deal with some experimental aspects that appear essential for optimizing the extracted energy, and have not yet been analyzed with sufficient detail. This investigation will help in evaluating those parameters which need to be fixed in a future CDLE device. These include the charging potential, the durations of the different cycle steps, the load resistance used, and the porosity and hydrophilicity of the carbon.