In the prospect of a huge development of energy production technologies from non-programmable renewable sources, hydrogen produced by electrolysis is a valid solution as an exploitable vector for the storage of excess energy in natural gas networks and infrastructures. It can in fact contribute to a progressive replacement of natural gas of fossil origin with so-called renewable gas. However, storing large quantities of hydrogen for long periods still poses potential problems which currently limit its use. One of them consists in the presence of microorganisms in the stored gas, in the networks and in underground tanks. The action of microbes can cause phenomena that alter the quality of the gas and induce corrosion of materials (microbiological corrosion or MIC). However, biofilms can also induce an inhibition of corrosion phenomena (MICI), altering the chemical-physical characteristics of the material surface. These so far underestimated phenomena are not fully known and are often countered with biocidal treatments, whose environmental impact may not be negligible. This report addresses these issues and reports the results of microbiological corrosion tests on steel and copper alloys, carried out using single strains and microbial pools present in rocks and underground waters.
In particular, the crucial role of the presence of biofilms and exopolymeric substances (EPS) produced by the bacteria themselves which can alter the corrosion behavior of both copper alloys and steel alloys in the opposite way was highlighted. Some electrochemical techniques were used, including electrochemical impedance spectroscopy (EIS) with a view to its possible future use for real-time monitoring of the effects and risks induced by microbial presence in storage tanks.