Flexibility in Great Britain’s gas networks: analysis of linepack

30 May 2019

This briefing note highlights the scale of flexibility currently provided by the high-pressure pipelines in Britain’s gas networks.    

Linepack and linepack flexibility

Linepack is the amount of gas contained within the higher-pressure tiers of Britain’s gas transmission and distribution network, literally, it is the amount of gas packed into the pipelines. Up until now discussion about linepack in the distribution network has been based on estimated values.

By analysing hourly data from the National Transmission System and the Gas Distribution Networks over a 63-month period, UKERC researchers have calculated the hourly levels of linepack and its variation within a day.

Network operators change the pressure in pipelines to vary the levels of linepack to help match supply and demand for gas. Within-day linepack flexibility can therefore be considered as the operational within-day storage of the gas pipelines themselves. 

The scale of linepack

Typically, linepack is highest at 06:00 hours (just before peak demand when people wake up and demand rapidly increases) and lowest at 21:00 hours (after peak evening demand).  The scale of values presented in the briefing note show the significant levels of within-day flexibility currently provided by the total gas network; for 50% of the days during the October to March heating season, the within-day flexibility was greater than 377 GWh.

The routine daily use of linepack flexibility (driven primarily by changes in demand for space and water heating) points to the critical role of the gas infrastructure in providing flexibility to Britain’s existing energy systems. Electrical networks have no equivalent intrinsic storage in the network itself.

Hydrogen is under consideration as a future low-carbon energy vector that would continue to use parts of gas infrastructure. Changing the composition of gas within the system requires detailed analyses to understand how much linepack that high-pressure pipelines could hold, and its potential to provide flexibility.

Reducing the need for within-day flexibility in the first place should be a priority, regardless of the choice of future primary energy supplies to achieve a net-zero target by 2050. The scale of current within-day flexibility is so great, that it would seem sensible to encourage several avenues of research and innovation at this point, with a view to narrowing down potential options in the future.

Download the briefing note

Watch a short animation comparing Great Britain's Local Gas Demand and National Electrical Demand