Science & Technology in Action

7th Edition

Extending the Natural Gas Network

Bord Gáis Networks

Several factors determine the viability of connecting a new town to the natural gas network. The most significant of these are: the expected demand or load, the cost of the pipeline extension, transmission and distribution costs, local authority charges and revenue from authorised shippers.
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Contains the full lesson along with a supporting toolkit, including teachers’ notes.

Lesson excerpt

Establishing the Viability for Connecting New Towns

The Gaslink Connections Policy sets out the criteria for connecting new towns to the natural gas network. To evaluate the potential viability for the connection of a new town, an economic appraisal is carried out. This appraisal takes into account the following:

  • Transmission and distribution network tariff revenues based on a forecast of the potential new housing and Industrial & Commercial loads in the town over 25 years against.
  • The estimated full connection costs (including both transmission and distribution elements) required to facilitate the projected load requirements in the town.

If the appraisal returns a positive result then the town is viable for connection to the Bord Gáis natural gas network subject to approval from the Commission for Energy Regulation.

Bord Gáis Networks generates revenues by applying the relevant transmission and distribution tariffs for the use of the pipeline system by shippers. At present there are twelve shippers signed up to the Code of Operations in ROI and one shipper in Northern Ireland.

Designing the Network

There are two main divisions of a gas distribution network:

  1. A transmission system which transports gas at high pressure (85 bar to 7 bar) from storage facilities to cities and towns.
  2. Distribution networks which transport at lower pressure (7bar to 20 mbar) to individual users.

Transmission pipes are made of steel, while distribution mains (local "gas pipes") are made of polyethylene (PE). These PE mains are used for pressures not exceeding 4 bar. PE mains have gradually replaced cast iron and other metallic mains.

Pipe sizing depends on the required final pressure (at thecustomer point) and on the expected load or demand. Potential large industrial/commercial and contract customers in the towns are consulted with regard to future expansion plans and these loads are catered for in the network design.

Quiz questions

  1. The cost of running the system is called ‘capital cost’. false
  2. A small commercial user is one who uses less than 200 MW h per year. true
  3. Existing houses were excluded in the feasibility assessment. true
  4. Peak hourly demand for a new housing customer is taken as 2 m3/h. false
  5. Capital costs also include local authority charges associated with road openings. true
  6. Distribution mains pipes are made of steel. false
  7. Bord Gáis generally uses a CPO to acquire land. false
  8. Polyethylene (PE) pipe is generally used in the distribution network. false
  9. PE pipe must not be used inside buildings. true