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Shrinkage Forum 04 June 2013

Shrinkage Forum 04 June 2013. Roy Malin. Best Practice - Areas of Inconsistency. Licence Obligations – Shrinkage and Leakage Model. DNs have a Licence obligation to maintain a Shrinkage and Leakage Model The inclusion of Shrinkage is a new addition for the RIIO price control period

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Shrinkage Forum 04 June 2013

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  1. Shrinkage Forum 04 June 2013 Roy Malin

  2. Best Practice - Areas of Inconsistency

  3. Licence Obligations – Shrinkage and Leakage Model • DNs have a Licence obligation to maintain a Shrinkage and Leakage Model • The inclusion of Shrinkage is a new addition for the RIIO price control period • Need to expand current model to include Theft of Gas (ToG) and Own Use Gas (OUG) • Propose that the current ToG and OUG processes are adopted into the Shrinkage and Leakage Model • Propose that this be done alongside the proposed Low Pressure Service Model changes

  4. Low Pressure Service Model Modification • In February 2012, National Grid published a consultation on a proposed revision to the Leakage Model in respect of the calculation of leakage from low pressure services • For leakage estimation purposes, services are split into four categories: Steel Service to Metallic Main, PE Service to Metallic Main, Steel Service to PE Main and PE service to PE main. • 2002/03 National Leakage Tests established that only service connections to metallic mains leak • Establish a new ‘baseline’ estimate of the number of services in each of the categories (using mains replacement data) • Update model to capture the impact on leakage of service transfers (model previously updated to capture the impact of service relays)

  5. Impact of LP ServiceModel Change • Impact is consistent with that already published for 2013/14 Initial Shrinkage Proposals • Establish a new ‘baseline’ estimate of the number of services • The RIIO Shrinkage and Leakage Baselines based on v1.3 Model • Impact determined by comparing the 2010/11 v1.3 Model output with that from the revised model for the same year • Impact will be the same for each year of the RIIO Price Control Period • Inclusion of Service Transfers • Average no transfers/km x anticipated mains replacement length x leakage rate • Impact will be cumulative from 2011/12 and over the RIIO Period • Change has no significant impact on incentives for DNs: • Re-baseline to 2010/11 - Baselines and Actual quantities will adjust by the same amount • Service Transfers – Baseline will be adjusted by an amount based on average transfer workload, whereas Actual quantity will be based actual transfer workload

  6. Impact of Model Change – Re-baseline 2010/11

  7. Impact of Model Change – Service Transfers

  8. Impact of Model Change – Combined (GWh)

  9. AGI Venting - Current Model • Current Methodology • ‘Fixed’ values based on a 1994 Watt Committee report • National estimate • Derivation unknown • National value apportioned across LDZs at time of Network Sale • Approximately 5% of over all emissions

  10. AGI Venting - Background • Two routinely venting components • Positioners • Controllers • Venting occurs both in steady state and during control actions • Each AGI usually has a number of Positioners and Controllers • Positioners and Controllers originally designed to work with compressed air but modified to work with gas, as readily available on site.

  11. AGI Venting - Proposal • Proposed Methodology • ‘Activity’ based estimation • Based on number of Positioners and Controllers • Estimate of Steady-state Venting • Manufacturers Data • Estimate of Operational Venting

  12. AGI Venting – IFI Project • Key deliverables • Verify Manufacturers Data • Establish relationship between venting rate and control system operating pressure for steady-state venting • Identify levels of venting in operation • Investigate the potential to relate operational venting to telemetered flow and pressure data • The viability of this will be assessed when data is available

  13. AGI Venting – Verification Manufacturers Data • Bristol Babcock Controller • 0.05cfm @ 20 PSI • Verified by lab tests • Linear relationship between control pressure and venting • Fisher Positioner • 0.3cfm @ 100 PSI • Verified by lab tests • Linear relationship between control pressure and venting

  14. AGI Venting – Next Steps • End of July – Complete IFI Work • August – Complete inventory of existing equipment • September – Issue Consultation on AGI Venting • October – Report on Consultation issued to Ofgem • December – Ofgem decision (in time for 2014/15 Shrinkage Proposals)

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