A bench scale laboratory experiment was conducted to assess the microbial corrosion and souring effects renewable natural gas (RNG) and natural gas amended with hydrogen have on underground gas storage systems. Steel coupon-containing vials inoculated with produced fluid from an underground storage well were subject to different headspace conditions to simulate underground gas storage. The vials were filled with geologic natural gas, geologic natural gas amended with hydrogen, RNG, and RNG amended with hydrogen. Each condition was subject to molecular (qPCR, and 16S rRNA analysis), liquid chemistry (sulfate and volatile fatty acid), corrosion, and headspace chemistry (major components and trace sulfur) analysis in duplicate at three time points. The results showed that levels of sulfide production, microbial community composition, and coupon mass loss did not differ greatly between the natural gas and RNG conditions. However, the presence of hydrogen did increase the levels of sulfide in both geologic and RNG conditions. There was also evidence of significant biotransformation of hydrogen into an organic acid (formate). This experiment has shown that microbes native to underground storage wells could have an impact on gas quality and corrosion (via hydrogen sulfide production) if hydrogen is introduced.