Under normal operating conditions supplies of gas entering the National Transmission System (NTS) are matched to the demand for gas leaving the system and pressures within the system remain within an acceptable range.
National Grid, as operator of the NTS, is responsible for ensuring that a supply – demand balance on the NTS is achieved. National Grid has a range of system balancing tools it makes use of to match supply and demand.
A Network Gas Supply Emergency (NGSE) occurs when National Grid is unable to maintain a supply – demand balance on the NTS using its normal system balancing tools. As a consequence of the imbalance between supply and demand pressures in the system fall and it may not be possible to safely maintain gas supplies to industrial and domestic gas consumers who are supplied with gas either directly or indirectly from the NTS.
A NSGE could be caused by a major loss of supplies to the system as a result of the failure of a gas terminal or as the result of damage to a NTS pipeline affecting the ability of the system to transport gas to consumers.
If National Grid was to be unable to maintain a supply – demand balance on the NTS using its normal system balancing tools, it would request the Network Emergency Co-ordinator (NEC) to declare a NGSE. The declaration of a NGSE would provide it with access to additional balancing tools for use in restoring a supply – demand balance. These emergency tools include requesting additional gas supplies be delivered to the NTS or requiring gas consumers, starting with the largest industrial consumers, to stop using gas. These tools will be used, under the authorisation of the NEC, to try to maintain supplies as long as possible to domestic gas consumers.
The co-operation of gas industry participants, including gas terminal operators, gas shipping companies, gas transportation companies and large industrial consumers is required to successfully implement the emergency system balancing actions. Sufficient emergency balancing actions will be undertaken to restore a supply-demand balance on the NTS and minimise the safety consequences of the emergency to gas consumers.
Once a supply – demand balance has been achieved and the safe operation of the system ensured, supplies will be restored to consumers a soon as practicable. Once supplies have been restored to all consumers who are supplied with gas directly from the NTS the end of the NGSE will be declared by the NEC.
There has, to date, never been a Network Gas Supply Emergency.
Emergency Planning TeamGas System OperationNational GridNational Grid HouseWarwick Technology ParkWarwickCV34 6DA
Interruptions to supply
Margins Notice and Gas Deficit Warnings
Procedure for Network Gas Supply Emergency (T/PM/E/1)
NEC 2014 Exercise Viper Report
NEC Industry Letter 2017