1. DN Operation Iain Ward DNCC Manager

2. Responsibilities  Licence Holder  Obligation For 1 In 20 Capacity  DNCC Operates Networks Under Direction of The DN  Winter / Summer Operating Strategy  Booked Capacities  Short Term Variations  DN Specific Issues  DNCC Makes Within-Day Decisions Regarding  Supply Demand Balancing  Control of Unbilled Energy  Plant Outage  Planned  Unplanned (faults)

3. Daily Operations – Key Stages  Forecast Demand  Define Diurnal Profile  Programme Intakes  Manage Demand Changes  Respond to NTS Change Requests

4. Manage LDZ Take, Demand and Stock

5. Forecast Demand  LDZ Level  Weather Data (NDM)  VLDMC OPNs (DM)  Approx 5% Demand Change per 1 deg C

6. Demands and Temperature Relationship

7. Define Diurnal Profile  Diurnal Swing in the Range 12 – 15%  Significance of Minimum Stock Time  Storage Deficit in most DNs  Storage Utilisation in Defined Order  DN Linepack  DN LP Storage  DN Bullets  NTS Flow Variation

8. Diurnal Profiles Supply Rate 120018002400 0600 Demand Profile B C AA Storage Requirement A + B - C Empty Holders & Linepack, Fill Holders & Linepack

9. Manage LDZ Take, Demand and Stock

10. Programme Intakes  Remote Control of Offtake Utilisation  Notifications to NTS via OPN Process  Day Ahead and Within Day Considerations  Meet Sub-LDZ Flow Requirements  Pressure vs Volumetric Control  Shrinkage Considerations  Plant Outage  Reflective of OCS Where Possible  Request Additional Flow Flex via OPN Where Necessary

11. Theddlethorpe Gas (38.2 - 38.7 MJ - m3) Bacton Gas (38.2 - 38.6 MJ/m3) St Fergus / Teesside Gas (39.2 - 41.5 MJ/m3) St Fergus Gas (40 - 41.5 MJ/m3) Easington/ Rough Gas (38.1 - 38.7 MJ/m3) St Fergus / Barrow Gas (38.4 - 41.5 MJ/m3) CV Management

12. Manage Demand Changes  Forecast Updated 8 Times Daily (UNC timings) plus up to 5 ad-hoc.  Respond to Revised Weather Data  Xmas period 2005; 5 degree error within day.  Rebalance DN Supply to Meet Demand Changes  Revised Offtake Rates  Impact on storage requirement  Allocation to Volumetric Offtakes; balance effect of pressure control?

13. Respond to NTS Change Requests  NTS To Anticipate Supply Rate Changes, Commercially and Physically Driven  NTS Outages  Planned e.g. On-Line Inspection  Un-Planned e.g. Faults  NTS VLDMC renominations

14. DNCC Offtake Performance  Booked Flat Capacity Limits Observed at DN Level  Booked Flow Flex Limits Exceeded at LDZ Level  Some Offtakes on Some Days  Pressure Controlled Flows Defined by Consumers  Within-day demand changes flow through into FlowFlex calculation.

15. LDZ 1

16. LDZ 2