Steel reinforced concrete electrodes for HVDC submarine cables

In HVDC submarine cable connections, electrodes design is paramount for technical and economic feasibility. The cathode is designed as simple as possible, if bidirectional operations are not required since reduction reactions does not produce corrosion of the material. The situation is completed reversed for the anodes submersed in seawater: in this case, the corrosion mechanism provokes removal of surface material. For this reason, in order to ensure a sufficiently high lifespan, the anode is usually made of different and more expensive materials, like titanium rods or meshes, coated with layers of a noble metal oxide, such as platinum, or a mixture of several of them. Sometimes the seawater anodes are also immersed in materials based on transition elements such as rare earths. In the present paper, an innovative prototype of seawater anodes, based on steel reinforced concrete, is presented. Moreover, its experimental comparison in seawater at corrosive phenomena is reported, comprising simple steel or titanium bars and titanium meshes protected by special multi metal oxides (MMO). These experiments have shown important reduction of the corrosion phenomena in the case of the prototype of anode made by steel concrete.