The identification of existing components and pipeline materials in high-pressure NG grids, and most critical RCS and bottlenecks for H2 injection into transmission gas grid was achieved (WP2). The resulting inventory database identified the crucial components that could be the problematic parts for the admixing of H2 into the natural gas grid.
A testing facility at FHA facilities was designed and commisioned (WP3). Actual materials, equipment and components of NG grid can be installed to expose them to different H2 concentrations and pressures.Testing campaigns ranging from 20 to 100 mol% H2 at 80 bar were carried out (WP4) to study the compatibility of different items to H2, regarding H2 embrittlement among another kind of damage due to hydrogen exposure, and potential leakages. H2/CH4 separation was also tackled by a separation prototype based on membrane technology.
Tested representative valves remains tight for the duration of the test, regardless the H2 content in the pipe. Constant displacement C-ring and 4pb steel specimen grades X42, X52, X60 and X70 did not show cracking when exposed to the different H2 gas compositions, at 80 bar pressure and test duration up to 3000 hours. No crack propagation was also noticed for the CT-WOL specimens. The Pd-based membrane prototype developed for H2/CH4 gas separation produced a permeate with a hydrogen purity of 99.5 mol%. Slow Strain Rate tests carried out at Tecnalia´s laboratory for X60 and X70 steels in 100 mol% H2, at 80 bar pressure yielded values of the notched tensile strength ratio indicative of low sensitivity to hydrogen embrittlement.
Regarding the modeling of H2 in the existing NG grid, the NG grid was abstracted as far as possible and considered reasonable and reduced to its essential components (WP5). Based on these fundamentals, a section of the NG grid was modelled in order to be solved numerically. An economic model was to compute transport costs based on the retrofit of the existing grid. The transport costs for hydrogen in different scenarios and contexts were calculated. The results were elaborated into a set of recommendations taking into account different conversion stages regarding the allowed H2 content in converted NG grid.
The potential of H2 injection into the European gas transmission grids in alignment with EU policies was studied (W6) based on the findings from WP2, techno-economic observations with respect to H2 injection into the gas grid from WP5 as well as technical conclusions from WP4. Besides, the interoperability, cross-border transport issues and the gas market management and strategies were reviewed. A pathway towards integrating H2 in the EU gas network was developed. The work performed can be considered as a collection and compilation activity resulting into a kind of compendium of the technical work, impacting regulation, codes, standards as well as implementation possibilities of H2 injection applications within HIGGS.
As part of the EU Hydrogen Week, the HIGGS project and the final results were presented in a closing conference as an official side event. A project brochure. distributed both in printed and digital form at the closing conference, was produced with the aim to condense the project results and make them available in a well edited and illustrated way.
