Can India's Gas Pipelines Carry Hydrogen? A 15,631 km Feasibility Assessment with 50% Cost Savings over New Construction

This study presents the first probabilistic assessment of India's natural gas pipeline network for hydrogen readiness, coupling NIST-grade thermodynamics (CoolProp) with industry-standard hydraulics (Panhandle B) and structural mechanics (ASME B31.12). Ten representative pipelines (7,733 km) are explicitly modelled with Monte Carlo analysis (100,000 samples across 8 uncertain variables), with results extrapolated to the full 24-pipeline network (15,631 km). Operating at 20 bar hydrogen—75% deration from natural gas design pressure—achieves 97% structural pass rate despite hydrogen embrittlement constraints. Sobol sensitivity analysis identifies operating pressure (66%) and wall thickness (22%) as dominant risk drivers. Economic analysis using AACE Class 4 methodology estimates repurposing at ₹15,000–18,000 Crores ($2.0–2.2B)—50–60% cheaper than new construction. The network provides ~200 GWh inherent linepack energy storage at zero incremental cost. A phased deployment strategy progressing from 10–20% H₂/NG blending to 100% hydrogen over 15+ years de-risks investment. Complete Python implementation, pipeline database, Monte Carlo samples, and cost calculations are provided as supplementary materials.