Comprehensive analysis of hydrogen compression and pipeline transportation from thermodynamics and safety aspects

Abstract

Hydrogen delivery is a critical contributor to costs, emissions, and energy consumption associated with hydrogen pathways involving central plant production. Pipeline transmission appears to be the most economical means of transporting large quantities of hydrogen over great distances. The aim of this study is to analyze H2 compression and pipeline transportation processes with safety issues related to water electrolysis and H2 production for different values of the hydrogen mass flow rate: 0.2, 0.5, 1.0, 2.0, and 2.8 kg/s. Pipelines are operated at an initial pressure of 10 MPa at 300 K. Depending on the hydrogen mass flow rate, various types of compressors have been proposed, including reciprocating, conventional multistage centrifugal compressors, and an eight-stage integrally geared centrifugal compressor based on the concept of advanced centrifugal stages. Another problem analyzed in this study is H2 pipeline transport from the compressor outlet site to salt caverns under heat-transfer conditions. In order to avoid the choking condition, recompression of H2 is necessary at appropriately selected transportation distances. Simulations are conducted to determine the maximum safe distance of the pipeline to subsequent booster stations depending on the mass flow rate, pipeline diameter, ambient temperature, thermal insulation thickness, and ground-level heat transfer conditions. This analysis makes it possible to select pipeline diameters of 0.065 m, 0.1 m, 0.15 m, and 025 m, depending on the pre-determined hydrogen mass flow rate, at the transportation distance of 50 km. If the H2 pipeline gets damaged and an uncontrollable release of hydrogen occurs, hydrogen pipeline transport poses a potential hazard to humans and the surroundings. In the case of a hydrogen jet fire, zones with a fatal effect on humans are presented.