National Transmission System

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The National Transmission System (NTS) is the network of gas pipelines throughout the United Kingdom that supply gas to 40 power stations from natural gas terminals situated on the coast, and also gas distribution companies which lead indirectly to homes.

Similarity to the National Grid[edit]

It is directly analogous to the UK's National Grid for electricity transmission: in fact it is looked after by the same company, National Grid plc, administratively based in Warwick (formerly in Hinckley). Although National Grid only owns the electrical transmission system in England and Wales, with the Scotland transmission system owned by two Scottish companies, the NTS is wholly owned by National Grid plc in England, Scotland and Wales.

History[edit]

North Sea Gas was first brought ashore in the UK in 1967, after which the NTS was built by British Gas. Before this, gas came locally from municipal gasworks. Most of the NTS was built in the 1970s and early 1980s. In February 1997, British Gas de-merged into two units, with the NTS being owned by BG plc, then in October 2000 by the de-merged Lattice Group. In October 2002, the Lattice Group merged with National Grid.

Operation[edit]

The system provides the arteries in the UK's gas network. It is the starting point for gas distribution before it reaches the pipeline system for houses, which is not part of the NTS, but the two systems form the gas distribution network of the UK.

There are two types of gas pipelines in the UK: large diameter high-pressure (up to 94 bar and 120cm diameter) pipelines - the type that the NTS uses, and smaller diameter lower pressure pipelines that connect to domestic uses in residential areas. The NTS has over 7,600km of welded steel gas pipeline with twenty four (mostly gas turbine driven) compressor stations and over 25 pressure regulators. Gas moves through the system at speeds up to 25 mph depending on pressures and pipeline diameters.

Compressor stations include:

Entry[edit]

Gas enters the system via the seven UK gas terminals (six in England and one in Scotland) and a variety of storage facilities. These include a mixture of salt cavity and LNG storage sites (onshore), and the depleated oil field at Rough (offshore).

Gas distribution network[edit]

The gas distribution network (to homes) is not part of the NTS. Companies that own part of this gas network, also known as the Local Transmission System (LTS), are known officially as Gas Transporters. Gas to this network enters via the NTS through a pressure reduction station to the twelve gas distribution zones in England, Scotland and Wales within eight distribution networks. In total, there are 275,000km of gas pipelines within this network. The LTS is managed from Hinckley, Leicestershire (former headquarters of the NTS). Financial transactions between the Gas Transporters are managed by Xoserve, based in Solihull. It was formerly an internal department of National Grid and is now an independent company.

For distribution to houses, National Grid plc (this division is based in Northampton) owns the network in North West England, the West Midlands, the East Midlands, the East of England and North London. In June 2005, National Grid sold some gas distribution networks and now in the North of England, it is owned by Northern Gas Networks; in the Wales and West by Wales and West Utilities; and in Southern England and Scotland by Scotia Gas Networks.

Northern Ireland[edit]

Northern Ireland is not part of the NTS per se, but gets its gas via the Scotland to Northern Ireland natural gas transmission pipeline (SNIP) owned by Premier Transmission and built in 1998. The gas network in Northern Ireland is split into two areas with one owned by Phoenix Natural Gas and the other by Firmus Energy.

See also[edit]

External links[edit]