Does a sacrificial anode cathodic protection system require an external power supply?

A sacrificial anode cathodic protection system does not require an external power supply because it operates on the principle of corrosion prevention through electrochemical reactions. In this system, sacrificial anodes, typically made of metals that corrode more easily than the metal of the structure being protected, are installed. When these anodes are connected to the storage tank or piping, they corrode instead of the structure, thereby providing protection.

The chemical reactions involved create a galvanic cell that generates the necessary current to protect the underground storage tank without needing an external energy source. This makes sacrificial anode systems self-sufficient and effective for long-term applications in cathodic protection.

Other options imply varying needs for external power, which are not relevant for a sacrificial anode system. For example, some other types of cathodic protection systems, like impressed current systems, do require an external power source to function. However, in the case of sacrificial anodes, the inherent characteristics of the materials involved provide all the necessary current for protection.