Overlooked risks in hydrogen transport: Hydrogen permeation drives microbial activity and accelerates corrosion

Repurposing natural gas pipelines for hydrogen transport is a cost-efficient strategy to accelerate the hydrogen economy. However, beyond the well-established risk of hydrogen embrittlement, hydrogen permeation may increase the intrinsic corrosion susceptibility of steel and create subsurface conditions that favour microbiologically influenced corrosion by enriching hydrogen-utilising microbial communities along buried pipelines. We exposed hydrogen-charged steel in a soil-inoculated medium containing a field-relevant microbial community and observed severe corrosion. The combined effects of hydrogen effusing and microbial activity led to excessive rust, carbonate, and carbonaceous compounds, intensifying localised attack. Pronounced microbial shifts were observed in response to hydrogen-charged specimens, favouring hydrogen-metabolising bacteria, indicating that hydrogen permeation stimulates metabolic activity and corrosion, revealing a corrosion mechanism currently overlooked in pipeline risk assessments.