Above ground tanks for storage of liquid hydrocarbon are often erected with secondary containment
membrane installed below the tank bottom to prevent the soil contamination in case of leakage.
The design of impressed current cathodic protection in presence of the plastic membrane is based on
distributed anodes installed in the space between the tank bottom and the membrane; among available
anodes, the most commonly used are the titanium grid or ribbon activated with noble metal oxides.
The configuration of the grid or ribbon anode system confined in the closed space between bottom and
membrane creates specific issues concerning the electrochemical reactions occurring at anode and
cathode, the ohmic drops in the anode system and the potential and current distribution at the cathode.
The paper shows results of a number of numeric simulations performed to predict the actual distribution
of current and potential. Design criteria are discussed.