In cathodic protection systems, what component is typically used to provide the necessary current?

In cathodic protection systems, active anodes are the components specifically designed to provide the necessary current to mitigate corrosion on metallic structures. These anodes are made from materials that can sacrifice themselves to protect the structure. When connected to the structure and a reference electrode, active anodes create a flow of electrons that travels to the metal surface, effectively preventing corrosion by ensuring that the metal remains in a reduced state.

Active anodes can be either impressed current anodes, where an external power source drives the protective current, or galvanic anodes, which rely on the natural electrochemical potential of the anode material (like zinc, magnesium, or aluminum) to produce current. This makes them crucial in delivering the protective current needed for effective cathodic protection.

The other options do not actively provide current in the same way active anodes do. Passive anodes do not supply current; instead, they rely on the surrounding environment and cathodic protection systems to prevent corrosion. Metallic shields and surface coatings can help protect against corrosion but do not generate current. Thus, active anodes are vital for ensuring effective cathodic protection.