In a heat exchanger, a major component of any power plant, a 20-micron thick bacterial layer (biofilm) can cause a 30% decrease in thermal efficiency: biofilm, indeed, is up to 4 times more insulating than calcium carbonate scale. Moreover, biofilm can increase inorganic fouling, producing sticky substances that increase particles adhesion. For these reasons, large amounts of chemical substances (biocides) are used to limit microbiological growth in such systems. A new application case regarding biofilm monitoring and optimization of water treatment in power plants was just published, it can be download from the ALVIM Biofilm Sensors page.