Gas

Feb 17 2010 By Mary Barabe

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For decades, gas has been delivered to homes and businesses throughout Britain. It has become the country's most dependable form of energy. National Grid owns and operates both the national transmission system (NTS) throughout Britain and a significant gas distribution network throughout England.

Gas is delivered to seven reception points (called beach terminals) by gas producers operating offshore facilities from more than 100 fields beneath the sea around the British Isles. In addition, a terminal at the Isle of Grain allows liquefied natural gas to be delivered to the terminal by sea.

After treatment, which includes checking the quality meets the safety requirements and measuring the calorific value (the amount of energy contained in the gas), it is transported through 275,000 km of iron, steel and polyethylene mains pipeline.

The NTS consists of more than 6,600 km of welded steel pipeline operating at pressures of up to 85 bar (85 times normal atmospheric pressure, over 1250 psi). The gas is pushed through the system using 26 strategically placed compressor stations.

From over 140 off-take points, the NTS supplies gas to 40 power stations, a small number of large industrial consumers and the 12 local distribution zones that contain pipes operating at lower pressure that eventually supply the consumer. These 12 zones are managed by eight gas distribution networks.

Following the sale by National Grid of four of the distribution networks, the owners of the distribution networks (in addition to the National Grid) include: Scotia Gas Networks, which have contracted operations to Scotland Gas Networks and Southern Gas; Wales and West Utilities; and Northern Gas Networks, which have contracted operations to United Utilities Operations.

Meeting emergency demands

Gas moves through the NTS system at 25 mph, which means that additional supplies cannot be delivered instantly when demand increases. So if gas is needed in Cornwall, for example, but there are only extra supplies in Scotland, it would take a day for the gas to reach its destination.

Because of this delay, the gas transmission system has to be kept constantly in balance - with constant buying and selling on the open market to ensure supplies are evenly distributed throughout Britain at all times. National Grid also has gas in store (‘top-up’ and ‘operating margins gas’) to ensure the system is balanced and that supplies are maintained.

Distribution

The gas in your home or business is supplied to you by a gas supplier. Only those licensed by the Office of Gas and Electricity Markets (Ofgem) can sell you gas. You can obtain a list of gas suppliers from the energywatch website.

Your gas supplier is responsible for providing a meter and organising for your meter to be read. You should contact your gas supplier to discuss any issues regarding your gas meter. You will find contact details for your gas supplier on your gas bill.

Reporting a leak

If you suspect a gas leak, call the National Grid 24-hour emergency number on 0800 111 999, avoid operating any electrical switches (on or off) and do not smoke or light a naked flame. Open doors and/or windows to ventilate the area, check your gas appliances and turn them off, and turn the gas supply off at the main meter.