In the next few decades, the world needs new energy sources to face population growth and increasing energy demand. Furthermore, these new energy sources must be renewable and sustainable in order to replace fossil energy. A good example can be the “blue energy”, an energy that can be harvested from the salinity difference of two solutions, the so-called “Salinity Gradient Power” (SPG). In particular, Capacitive Mixing (CapMix) is a SGP technique that recovers energy by cyclically injecting high and low salinity water in a cell. The aim of this thesis is to demonstrate that CapMix can be performed using carbon nanotubes (CNTs) based electrodes in a supercapacitor device with NaCl solutions.