1. Transmission Workstream 6th November 2008
Modification Proposal: Amendment to px (TGPP) Limited Network Entry Agreement
Transmission Workstream
6th November 2008

2. Background 1
The Wobbe Index of a unit of gas provides a measure of the energy released during combustion. The Calorific Value (CV) of a unit of gas provides a measure of the heat released during combustion.
GS(M)R limits the range of Wobbe Index that National Grid Gas (NGG) can accept into the NTS to between and MJ/m3 for safety reasons. The GS(M)R CV range is between 42.3 and 36.9 MJ/m3.
The site specific limits to Wobbe Index and Calorific Value are detailed in the Network Entry Provisions in the px (TGPP) Network Entry Agreement (NEA).
The Wobbe Limits and CV ranges set out in the px (TGPP) NEA are more restrictive than necessary to satisfy GS(M)R.

3. Background 2
Energy24 believes that other ASEPs have been given the full GS(M)R range for Wobbe and CV and the existing px (TGPP) Network Entry Provisions may act to constrain the amount of gas that can enter the NTS at this Teesside ASEP.
The proposal, therefore, is to align the px (TGGP) Network Entry Provisions with the GS(M)R limits
In addition, the delivery pressure of gas into the NTS as stated in the px (TGPP) Network Entry Provisions is currently 75 barg. The actual pressure rating of the pipe-work downstream of the Teesside ASEP is 70 barg and it is therefore proposed to correct this anomaly.

4. Modification Proposal [Insert Proposal Number]
Proposal [insert mod number ] seeks to:
Lower the minimum Wobbe Limit set out in px (TGPP) Network Entry Provisions to the GS(M)R limit of 47.20MJ/m3.
Reduce the CV lower range set out in the px (TGPP) Network Entry Provisions to align with the lower GS(M)R range of 36.9MJ/m3.
Lower the Delivery Pressure set out in the px (TGPP) Network Entry Provisions to 70barg to reflect the physical capability of the downstream pipe-work.
Energy24 believes that National Grid supports these changes

5. Modification Proposal [Insert Mod Number]
Benefits:
Enhance the availability of gas supplies at the Teesside System Entry Point
Offer increased scope to process a wider range of offshore gas supplies and support the development of new gas fields with different gas compositions
Enhanced Security of supply by supporting UKCS production
Increased competition between ASEPs to attract offshore production