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Flow Variations at Entry

Flow Variations at Entry. Transmission Workstream Martin Watson 1 st November 2007. Objectives. Overview of Flow Variations at Entry Rates of Delivery as defined by UNC Example of within day Flow Variations Frontloading/Backloading Flow Variations at Entry Oct 2006 – Sept 2007.

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Flow Variations at Entry

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  1. Flow Variations at Entry Transmission Workstream Martin Watson 1st November 2007

  2. Objectives • Overview of Flow Variations at Entry • Rates of Delivery as defined by UNC • Example of within day Flow Variations • Frontloading/Backloading • Flow Variations at Entry Oct 2006 – Sept 2007

  3. Flow Variations at Entry Flow Variation = (EOD/24 * 16) - (Sum of 06.00 to 22.00 Hourly Volumes) = ( 240 x 16) - ( 5 x 16) 24 = 160 - 80 = 80 Gwh Extent of Backloading = 80 Gwh 20 End of Day Measurement = 240 Gwh 10 5 0 06.00 06.00 22.00 16 hours

  4. Rates of Delivery Re-nomination to increase flow to 1.8 mcm/hr Re-nomination to increase flow to 1.6 mcm/hr Re-nomination to decrease flow to 0.6 mcm/hr Start of day nomination – 1/24th rate of 1.2 mcm/hr UNC Section I 3.10 - Rates of Delivery 3.10.1 Each User shall use all reasonable endeavours to secure that the requirements of paragraph 3.10.2 are complied with……… 3.10.2 (a) The rate at which it delivers gas to the Total system at a System Entry Point changes only with effect from the start of the day and (within the day) with effect from the Re-nomination Effective Time of a Re-nomination in respect of that point.

  5. Example of within day flow variation20th July 2007

  6. 20th July 2007 - Demand and Supply

  7. 20th July 2007 – NTS Actual Linepack Linepack depleting at up to 2mcm/hr Linepack depletion 16.2 mcm

  8. Impact on Capacity Release of Backloading/Frontloading

  9. Backloading Maximum capability Capacity that may not be released due to profiling NG less likely to release additional capacity if flows are being profiled or there is an expectation, based on past experience of large within day flow variations 1/24th flow rate Actual flow profile

  10. Frontloading Maximum capability Capacity that may not be released due to profiling NG less likely to release additional capacity if flows are being profiled or there is an expectation, based on past experience of large within day flow variations 1/24th flow rate Actual flow profile

  11. Flow VariationsOctober 2006 – September 2007

  12. Teesside Backloading +ve Net Input flows in period 06.00 to 22.00 BELOW average flows for the day Frontloading -ve Net Input flows in period 06.00 to 22.00 ABOVE average flows for the day

  13. Barrow

  14. Bacton

  15. St Fergus

  16. Easington Backloading +ve Net Input flows in period 06.00 to 22.00 BELOW average flows for the day Frontloading -ve Net Input flows in period 06.00 to 22.00 ABOVE average flows for the day

  17. Conclusions

  18. Conclusions • UNC obligations require Shippers to flow at a uniform rate, signalling any changes via the re-nomination process. • When Shippers do not flow at a uniform rate, it effects the operational efficiency of the NTS and the ability to maximise the release of additional capacity e.g. discretionary interruptible. • NGG and Shippers need to work together to minimise flow variations. • However, if Entry Terminals consistently demonstrate behaviours that compromise the safe and efficient operation of the NTS, NGG will look to bring forward timely measures to address this issue.

  19. End

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