National Grid doubles length of this year's UK gas emergency test

UK gas system operator National Grid has set aside four days for its annual emergency simulation in September and October, double last year's exercise period, information from the company showed Aug. 23.

Last year, two days were set aside to run a scenario of high gas demand (400 million cu m/d, as seen Feb. 11, 2021) with gas forming 45% of the power generation mix.

"It is essential for the gas industry to be able to manage an emergency situation safely and effectively; the annual exercise is one of the key methods to demonstrating its preparedness," National Grid said in a briefing note.

The event, named Exercise Degree, is to take place on Sept. 13-14 and on Oct. 4-5.

Mock demand data will be used to simulate a series of supply losses, triggering a Network Gas Supply Emergency.

A range of industry alerts will be activated during the test, namely a Gas Balancing Notification, Margins Notice and Emergency Declarations, the note said.

"Exercise Degree will look to test that both gas and electricity participants can appropriately respond to a gas supply shortage which has electricity system implications," it said.

Last year's post-exercise briefing noted that 96% of the 52 sites directly connected to the national gas transmission system "could be contacted and would stop using gas within one hour."

At local distribution level, 91% of some 2,600 sites were contactable and would stop using gas, it said. Some 50 sites contacted would not stop using gas.

The UK has long-standing gas emergency procedures in place, aimed at preserving household supply above all else.

The procedures, first published in 1997 and updated in May 2021, list actions that can be taken in a supply emergency, from use of storage gas and the easing of gas specification rules through to load shedding on interconnectors or via interruptible supply contracts.

A final resort ahead of actual supply cuts would be public appeals to domestic and small commercial consumers to use "as little gas as possible", or indeed "to stop using gas."

Testing an industry-wide media response and public appeals process was part of last year's emergency simulations.

Over 350 industry participants took part in the exercise, including terminal operators, storage facilities, network operators, interconnectors and shippers, as well as regulator Ofgem, business ministry BEIS and the Oil and Gas Authority.