What is the primary function of a cathodic protection system used to protect subsea structures in a tidal energy plant?

The primary function of a cathodic protection system used to protect subsea structures in a tidal energy plant is to prevent or significantly reduce corrosion of metallic structures exposed to the marine environment by making the structure the cathode in an electrochemical cell, thereby sacrificing a less noble metal (the anode) to corrosion instead. Corrosion is the degradation of metals through electrochemical reactions with their environment. In the marine environment, saltwater acts as an electrolyte, facilitating the flow of electrons between different areas of a metal surface. This leads to the formation of anodic (corrosion) and cathodic (protected) regions. Cathodic protection (CP) systems work by introducing an external anode, which is a metal that is more easily corroded than the structure being protected. This creates a galvanic cell where the anode corrodes preferentially, protecting the subsea structure from corrosion. There are two main types of cathodic protection systems: sacrificial anode systems and impressed current cathodic protection (ICCP) systems. Sacrificial anode systems use anodes made of metals such as zinc, aluminum, or magnesium, which are naturally more reactive than steel. These anodes are electrically connected to the subsea structure, and they corrode over time, protecting the structure. Impressed current cathodic protection (ICCP) systems use an external power supply to drive current from an anode to the subsea structure. The anodes are typically made of inert materials such as mixed metal oxides. ICCP systems are more complex than sacrificial anode systems, but they can provide a higher level of protection and are suitable for large or complex structures. By effectively preventing corrosion, cathodic protection systems extend the lifespan of subsea structures in tidal energy plants, reducing maintenance costs and ensuring the long-term reliability of the plant. For example, without cathodic protection, the steel foundations of a tidal turbine could corrode rapidly in the saltwater environment, leading to structural failure. With cathodic protection, the corrosion is concentrated on the sacrificial anodes, which can be replaced periodically, protecting the steel foundation.