SIF Alpha Phase - Velocity Design with Hydrogen, Summary Report

The current UK natural gas networks, operated by the Gas Distribution Networks, have the potential to flow blended hydrogen and to be re-purposed to flow 100% hydrogen. The hydrogen networks would therefore have the potential to contribute to Ofgem’s strategic innovation fund (SIF) decarbonisation of heat challenge, to help meet national 2030 and 2050 emissions targets.
To demonstrate how the current gas networks can be intelligently and efficiently transitioned to provide low carbon heating, the gas velocity constraints for hydrogen, applied at the design stage, need to be identified. These constraints will directly impact the level of capital investment required in the transition of the system to accommodate blended and 100% hydrogen.
However, hydrogen gas does not contain the same level of energy by volume as natural gas, so the volume of hydrogen flowing to consumers would have to increase a little over 3 times for an 100% hydrogen network to deliver energy at an equivalent rate, compared to natural gas. Without network reinforcement, this increase in flow could require a significant increase to the pressure and/or velocity of gas.
Currently, IGEM standards specify a nominal maximum velocity of 20 m/s, mainly to avoid the risk of debris within the pipes being picked up by the gas stream and causing wear to pipe components, possibly then resulting in early failure. A velocity limit of 40 m/s is assumed where the pipe assets are assumed to be clean.
Debris may be present in the system, particularly in the lower pressure tiers, in the form of dust, mainly, as a product of the historic manufacture of towns gas. Whilst many metallic mains, particularly in the LP pressure tier, have been replaced with PE (polyethylene) piping under the ongoing replacement scheme, it is anticipated that debris will still be present in the pipes that have not been replaced, and may have already been transported into the plastic pipes. Hydrogen has different properties to natural gas, so it is not known if debris may be picked up to the same degree or if any other factor will limit velocity. Other factors such as noise and/or vibration may also constrain the design velocity of gas in the system.
Building on this initial work, it was envisaged that validation of the pipe network behaviour would require full scale testing to investigate the erosion, vibration and noise behaviour associated with transportation of hydrogen and hydrogen blends with natural gas, to support the objective of validating and enhancing existing models. To develop the requirements for such testing, the “Alpha phase” (this phase) of the SIF project was initiated, with the intention of delivering conceptual designs of the full-scale test facilities, a detailed test programme, and to undertake any associated laboratory testing which would be required to support these activities.
This report summarises the SIF alpha phase conclusions and recommendations from work packages 1 to 5:
Work package 1 Conceptual design of test facilities
Work package 2 Detailed test plan
Work package 3 Laboratory testing
Work package 4 Network engagement
Work package 5 Cost-benefit analysis
This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating, which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.
Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.