Microbiologically influenced corrosion in a geothermal electric power plant

Microbiologically influenced corrosion is an important factor in the pitting of types 304L and 316L stainless steel (SS) (UMS S30403) structures in a geothermal electric power plant operating at temperatures > 100°C. Several species of thermophilic bacteria were detected and isolated at different temperatures. Desulfotomaculum spp., isolated at the 50-MW power unit, contributed to pitting of the 304L SS surface condenser tubes. Unidentified thermophilic sulfate-reducing bacteria were detected in the geothermal water used to heat the organic fluid in the heat exchanger of the 1.5-MW binary-cycle power unit.