Reuse of natural gas pipelines for hydrogen: a proposed conceptual model.
Hydrogen, pipelines, hydrogen embrittlement, repurposing of gas pipelines.
This study investigates the strategies and the technical and operational prerequisites for the successful integration of hydrogen (H2) into natural gas (GN) pipeline infrastructure, recognizing H2 as an essential vector for decarbonization. The central objective was to analyze the necessary approaches to overcome obstacles and enable the safe and efficient flow of H2, utilizing a conceptual model as a tool for systematization and analysis. The analysis demonstrated that the physicochemical properties of H2 generate significant challenges, with the main technical obstacle being hydrogen embrittlement caused in the steels that make up the pipelines. The repurpose of GN pipelines proved to be a promising strategy, which can offer a substantial reduction in investment costs compared to building dedicated networks. However, this feasibility is conditioned on the implementation of specific technical solutions for H2. The gradual introduction of H2 into the GN network is the most accepted approach currently, as it allows for H2 proportions between 5% and 20%, making it technically viable and avoiding major modifications to end-user equipment. Progression to pure H2 is shown as a long-term goal, requiring technological and regulatory maturation. The study synthesizes these findings into a framework of guidelines, which aim to provide basic orientations regarding the steps for implementing projects to repurpose GN pipelines for H2 transport. Recommendations for future work include deepening studies on embrittlement in high-strength steels and the development of adequate coatings.