The use of the natural-gas pipeline infrastructure for hydrogen transport in a changing market structure

Redox gradients in distribution systems influence water quality, corrosion, and microbial ecology.

SUMMARY

This paper analyses the transportation and delivery features of hydrogen as energy market evolves and approaches a fully functional Hydrogen economy. Initially physical aspects have been assessed that affect the flow of hydrogen through the existing pipeline infrastructure. Line pack and compressors are the only identified problems that need to be addressed. This is followed by an investigation into the mixing of hydrogen with natural gas gradually. It was revealed that a mix of up to 17% by volume does not have any significant effect, however higher concentration of hydrogen leads to a changeover of high-pressure grid pipelines as well as the end-user applications. It is suggested that initially hydrogen can be introduced in the distribution system, while emphasizing towards developing means for high-pressure transportation of hydrogen fuel gas. Government policies towards encouraging use of hydrogen in an evolving market is important for widespread and early assimilation in energy mix. Renewable sources of energy are recommended for distributed generation of hydrogen along the pipeline network. Copyright © 2011 John Wiley & Sons, Ltd.

Prospects of natural gas pipeline infrastructure in hydrogen transportation

Hydrogen is purported to be the future energy carrier. To realize a flourishing hydrogen economy it is imperative that a smooth energy supply chain is in place from the production to the user end. Pipeline networks have remained the most cost-effective method for supplying gas to the consumers. This chapter analyzes the process of hydrogen transportation through pipelines along with its challenges. Renewable resources have been analyzed in detail to replace fossil fuels as an alternate pathway for reliable hydrogen production. Hydrogen can also travel as a mixture with natural gas during the transition phase. Research on materials and process can effectively address the challenges in pipeline transportation.

Hydrogen transportation by pipelines

Addition of Hydrogen to Natural Gas

Hydrogen Diffusion through Plastic Pipes

Long-term tests on electro fused joints in PE pipes

The long-term quality of electro fused joints in third, second and excavated first generation PE pipes was compared. Pipes from all three generations were joined using couplers produced from PE80 and PE100 resins. Six brands of PE pipes and three brands of electro fusion couplers were used and all 18 combinations were tested. Both a short-term test (the Peel Test according to ISO 13954:1997) and a long-term test (the Slow Peel Test - SPT) were used to assess joint integrity. The latter test typically takes 500 hours at 80 or 95 °C. No failures at the joint plane occurred in either of the two tests, even for excavated first generation PE pipes. Whilst in the Peel Test failures often occur in the coupler, the Slow Peel Test exclusively produces slow brittle crack growth in the PE pipe wall. The time to failure in the Slow Peel Test on the joint is therefore governed by the resistance to slow crack growth of the pipe. These resistances vary widely between first, second and third generation pipes. The scope of the Slow Peel Test programme was further widened by using it on the new type of “VRC” PE100 materials. These “Very Resistant to Cracks” pipe materials possess a much higher resistance to slow crack growth than traditional PE100 pipe materials. Improved results of Slow Peel Testing on joints made with a “VRC” material have been obtained. Up to now, unwanted joint plane failures have never been found in Slow Peel Tests on electro fused PE pipes, including excavated first generation PE pipes. Such failures can only be produced by performing Slow Peel Tests on electro fused cross linked PE pipes. On such samples, the Slow Peel test can provide much clearer differences in electro fusion joint quality than the Peel Test at 23 °C. A comparison was also made with another long-term test on electro fused joints, according to DVS 2203-4, Appendix 1. It appears that that test can only prove a longterm Fusion Factor (load ability of the joint divided by the load ability of un-fused pipe, assessed in a long-term test) of not higher than 44 %. Therefore this test is less critical for electro fused joints in PE pipes.

The slow peel test as a tool for assessing the integrity of electro fused joints

Polyamide 11,12 and 6.12 for High-Pressure Gas Pipelines

The kinetics of physical ageing of un-plasticized P VC was investigated using Differential Scanning Calorimetry. A quantitative model was set up that describes the influence of ageing time and temperature on the well-known endothermic ageing peak. The activation energy for physical ageing of 116 kJoule/mole is very close to the literature value (115 kJoule/mole). Physical ageing of uPVC pipes leads to a decrease i n impact resistance and may ‐ for uPVC water pipes ‐ decrease the water hammer resistance. To study this, Rapid Crack Propagation measurements were performed, to assess the Critical Pressure. Crack initiation was always performed where the wall was at its thickest. Thus, RCP data was obtained with about 80% less scatter than usual. Excavated uPVC gas and water pipes have absorbed varying concentrations of water (maximum uptake 0.6 %) and carbon dioxide, which both act as plasticizer. Along with physical ageing these phenomena may affect impact performance.

Frans L. Scholten

Papers

Hydrogen Diffusion through Plastic Pipes

Long-term tests on electro fused joints in PE pipes

The slow peel test as a tool for assessing the integrity of electro fused joints

Polyamide 11,12 and 6.12 for High-Pressure Gas Pipelines

Physical Ageing of uPVC Gas and Water Pipes