Emergency Curtailment Quantity

The Uniform Network Code (UNC) Modification 044, ‘Emergency Revised Emergency Cash Out and Curtailment Arrangements’, was approved by Ofgem and has been effective from 1st October 2005. 

The objective of the modification is to ensure that shippers imbalance positions for the day are unchanged if Transporters emergency curtail the offtake of gas at Sites as part of a Gas Deficit Emergency. The trade quantities are billed and accounted for as part of the cash out neutrality process. 

The modification has two key elements:

·        The existing P70 process has been extended.  Shippers are now required to notify the relevant transporter if they commercially interrupt interruptible or firm customers and as a result, a site ceases taking gas.

·        The calculation and associated trade of the ‘Emergency Curtailment Quantity’ in the event that a transporter curtails gas offtake by a site in a Gas Deficit Emergency.

The calculation of the Emergency Curtailment Quantity (ECQ) is defined within UNC TPD Section Q 6 as “The quantity of gas (in kWh) which the Transporters, in aggregate, reasonably estimate that Users would have offtaken from the Total System at System Exit Points in respect of which Emergency Curtailment has occurred but for the fact that Emergency Curtailment had occurred at those System Exit Points”

The UNC requires each transporter to calculate the ECQ for each shipper in the event that the relevant transporter calls for emergency curtailment as part of a Gas Deficit Emergency.  Emergency curtailment covers both Emergency Interruption within a Potential Gas Deficit Emergency (Stage 1 ~ Potential GDE) and Firm load shedding in stage 3 of an actual GDE.

The following link to the Joint Office Website provides the detail of the current ECQ methodology.

http://www.gasgovernance.com/Code/UNCRel/