We will need many large new transmission systems for gathering and delivering Earth’s vast, diverse, dispersed, renewable energy resources. Both high voltage direct current electricity (HVDC) and gaseous hydrogen (GH2) pipeline are attractive, complementary, and competitive.

New natural gas (NG) transmission pipeline systems may be built with line pipe capable of 100% GH2, for future conversion to “renewables-hydrogen service” (RHS) at up to 100% GH2, to bring energy from windpower, biomass and other distant renewable sources to market as, and after, the NG is depleted. Since well-constructed and well-maintained pipelines have very long service lives, the increased investment required for construction with RHS-capable line pipe may be justified. These pipeline systems may be retrofitted with compressors, meters, valves and other fittings necessary for future RHS, for the nascent "renewables-hydrogen economy".

Pipelining GH2 costs ~1.3 - 1.8 times the NG cost because (a) volumetric energy density of hydrogen is one-third that of methane, and (b) hydrogen attack on pipeline steel must be prevented. The initial incremental investment in line pipe oversized in diameter and pressure capability for NG service may be difficult to justify; it represents excess, unused capacity during the period of NG service.

Although industry has been safely pipelining GH2 for decades, these systems are not designed for frequently-varying pressure and for large-scale, long-distance, cross-country collection, as required by RHS. No pipelines for such service exist. The public is unfamiliar with hydrogen and anxious about its safety. Thus, a new pilot-scale R&D and demonstration pipeline system, an International Renewable Hydrogen Transmission Demonstration Facility (IRHTDF), is needed to demonstrate technical and economic feasibility. We describe and offer a preliminary design for IRHTDF.