Upgrading our existing network

On the western leg of our network, enabling the transition to net zero means we’re on schedule to increase capacity to accommodate more gas from South Hook LNG terminal from 2025. 

How we achieve this increase in capacity is important – construction has environmental and community impacts, the cost of which is met by households and businesses through energy bills. 

A thorough and detailed analysis of our network revealed how we can increase capacity through the least amount of new infrastructure, the least impact on people and the environment, and at the least cost. It represents the best value for UK consumers. 

Increasing pressure

Part of this work will include increasing the pressure at which gas moves through our underground gas pipelines on the western leg of our network, allowing more gas to travel through the existing pipeline. This increase in pressure is referred to as uprating. We are working closely with the Health and Safety Executive to demonstrate that the network will continue to meet stringent safety standards with these small increases. We must modify some of our existing Above Ground Installation (AGI) sites to enable this uprating. 

There are a number of AGI sites which will require upgrade work, and each plays an important part in managing the pressure of the gas pipeline. Most of the AGIs will require relatively minor modifications to existing structures. A few others require some additional equipment or modest extensions either within National Gas Transmission’s existing land ownership or onto land not in National Gas ownership. 

These AGIs are: 

• Altwern 
• Felindre 
• Three Cocks 
• Llanwrda 
• Tirley 

Because we’re upgrading existing infrastructure, much of the work can be undertaken as permitted development (this describes certain types of work which can be undertaken without needing to apply for planning permission) though we do notify the relevant local authority and agree with them measures to be adopted to reduce the potential effects from the construction work. We do, however, need consent from local authorities for some parts of the project - and in a few cases to work with landowners whose property will host the infrastructure. We’d also like to hear from the local community - their feedback will help us to design construction activity in the most appropriate way. Currently work is programmed for 2024, but this may be subject to change.