1. Simon Trivella – 22nd May 2008 Distribution Workstream
UNC Modification Enduring Arrangements for Supply Point Capacity decrease at an Interruptible Supply Point
Simon Trivella – 22nd May 2008
Distribution Workstream

2. Background UNC Modification Proposal 0090 (1st April 2008)
Revised DN Interruption Arrangements
Transitional Period 1 April 2008 to 30 September 2011
1st Annual Auction to take place in June 2008
Gas Years 2011/12 to 2015/16

3. Current Arrangements (Mod 0090)
Any increase or decrease in Supply Point Capacity is covered by UNC TPD Section G 6.1.6
Any increased Capacity is deemed to be Firm Capacity (F)
Proposal 0215 does not seek to change this
More Complex arrangements for any decrease in Capacity
Proposal 0215 seeks to make these arrangements more flexible for all parties involved

4. Current Arrangements (Mod 0090)
Overall Interruption Price (OIP)
The total amount payable by the DNO based on a fully exercised annual contract (Option & Exercise Price) in p/kWh/Day
Interruptible Tranche (Tn)
A portion of Supply Point Capacity (in kWh/Day) (up to 100%) designated as Interruptible
Maximum number of Tranches per Supply Point in any Interruptible Period (Gas Year) is 9 (T1, T2 , …. , T9)

5. Capacity Reductions (Mod 0090)
Ranking
The Interruptible Tranches at a Supply Point are ranked in order of OIP, highest first
Example
4 Interruptible Tranches (T1, T2, T3 & T4)
All equal to 20% of SP SOQ
Firm Capacity (F) equal to 20%
20% : 80% split of Firm and Interruptible Capacity

6. Capacity Reductions T4 T3 T2 T1 F Ranking T1 OIP = 0.05 p/kWh/Day
Firm has OIP = 0.0 p/kWh/Day
(SP SOQ) T4 T3 T2 T1 F

7. Capacity Reductions T1 T2 T3 T4 F 40% SOQ Reduction
Tranches T1 & T2 extinguished
T3 & T4 both equal 33.3%
Firm Capacity equal 33.3%
Moved from 20:80 to 33:67
Consistent with site capabilities?
(SP SOQ) T1 T2 T3 T4 F

8. Capacity Reductions T1 T2 T3 T4 F 50% SOQ Reduction
Tranches T1 & T2 extinguished
If remainder of T3 is < MIA
T3 becomes Firm Capacity (60%)
If remainder of T3 is > MIA
T3 remains at reduced level
Firm Capacity equals 40%
Significant impact on F:I split
(SP SOQ) T1 T2 T3 T4 F

9. Reduction of inflated SOQ
SOQ is 2 times actual
50% SOQ Reduction
Tranche extinguished
Site becomes 100% Firm
(SP SOQ) T1 F

10. Mod 0215 Proposal Current Arrangements remain as default
Ability for reduced Capacity to be taken from:
Interruptible Tranche(s) (Tn)
Firm Capacity
Both
Only on Agreement from User and DNO, else default applies

11. Advantages Greater flexibility for all Parties End Consumer / User
Ability to retain Firm : Interruptible split that reflects actual capabilities
Distribution Network Operator
Ability to retain Interruptible Capacity in a Interruption Zone
Future constraints / demand
Satisfy overall Interruption Zone requirements

12. Disadvantages
None

13. Simon Trivella – 22nd May 2008 Distribution Workstream
UNC Modification Enduring Arrangements for Supply Point Capacity decrease at an Interruptible Supply Point
Simon Trivella – 22nd May 2008
Distribution Workstream