Learnings

Outcomes

Key outputs and recommendations from this project are as follows:

• No further action is recommended from the sensitivity analysis, with only negligible improvements possible
• AGI leakage is likely to be lower in practice than the LRMM estimates – field work to measure leakage from AGIs is likely not cost proportionate in isolation. However, it is recommended that as part of a system transformation to hydrogen, which will require adaptation at multiple AGIs, leakage management and accuracy measurements may be more appropriate as part of this process.
• AGI working losses from venting are estimated to be overstated in the LRMM – a fivefold reduction is likely subject to validation at a statistically representative number of sites.
• Cathodically protected streel pipes can be reclassified in the LRMM with a new leakage factor, 96.5% lower than the current rate which does not account for CP rates.
• CISBOT treated large diameter cast iron pipes (with remediated joints), are recommend to be reclassified in the LRMM with a new derived leakage factor 50.9% less than that current rate used, which does not account for remediated joints)
• Significant asset record discrepancies are likely in Cast iron asset records. This is likely due to digitisation and does not impact on asset risk scores. 132km of cast iron pipes across the SGN network are likely to be incorrectly classified and are likely to be spun iron. A validation methodology has been proposed which has the potential to reduce leakage of methane significantly
• The current LRMM can be adapted for use with hydrogen to ensure accurate estimate of future leakage. It is expected that indirect emissions from leakage of hydrogen will result in significant reduction compared to the direct emissions of natural gas leakage today. This reduction is likely to be higher when network improvements to make ready the end to end system for hydrogen are complete.
• There is a significant opportunity to increase quantifiable and qualitative understanding and management of methane leakage today and hydrogen leakage of the future as part of the adaptation of existing infrastructure (e.g. AGI work during AGI adaptation work)

Lessons Learnt

The learnings from this project have significant potential to lead to further validation work. The data gathered and analysed by the project, including data underpinning the LRMM is underpinned by from the national leakage tests, was challenging to collate and rationalise with SGN’s operational and maintenance data. No significant problems were encountered as part of this project