Cooling Circuits Pierangela Cristiani* Capitolo Libro: Biofouling: Types, Impact and Anti-Fouling Casa editrice Nova Sciences Publication (New York) * ERSE SpA Two main phenomena dramatically reduce the functionality of cooling circuits, especially in the marine environment: the settlement of macrofouling in cooling canals and the formation of biofilm on surfaces of heat exchangers. A power plant can lose more than 5% of its efficiency due to biological films and, at worst, the power units must be shut down if macrofouling plugs the tubes of condensers. The biocide used for industrial cooling circuits is mainly chlorine. Despite the need for such products, a growing attention is being paid to public health and to possible environmental damage deriving from the use of biocide treatments and by-products. Because of these issues, the developments of innovative and sustainable treatments as well as the careful monitoring of their effects are mandatory. In this context, innovative electrochemical tools described in this chapter give in several ways a valid help to plant operators. The attention is focalized on the innovative electrochemical monitoring tools enabling plant operators to optimize the antifouling treatments. In particular, an innovative integrated equipment specifically set for industrial application in cooling circuits and suitable to monitor several parameters simultaneously, including corrosion (by Linear Polarization Resistance technique), biofilm growth (by the BIOX electrochemical probe) as well as the chlorination treatment (by electrochemical and colorimetric methods) and other physical-chemical parameters of the water is described in detail. The best antifouling solutions based on the combination of mechanical/chemical products are also described and discussed, in light of monitoring campaigns conducted with the electrochemical tools. Some of these are based on alternative oxidant products such as Chlorine Dioxide and Peracetic Acid. An advanced application of electro-chlorination of Titanium by anodic polarization in seawater is described at the end of the chapter.