Introduction to NTS Entry Capacity
Capacity gives shippers an entitlement to flow gas onto the National Transmission System (NTS), and so capacity is often also referred to as ‘rights’ or ‘entitlements’. A shipper needs to buy 1 unit of capacity in order to flow 1 unit of energy onto the system and this is known as the ‘ticket to ride’ principle. Units for both capacity and energy are in kWh/day.
Firm & Interruptible Capacity
National Grid makes firm and interruptible NTS Entry capacity available to the market at each Aggregated System Entry Point (ASEP). The volume of firm capacity made available at each ASEP consists of the following amounts:
Baseline NTS Entry Capacity (obligated) – as defined by National Grid’s Gas Transporters Licence
Incremental NTS Entry Capacity (obligated) – Firm capacity made available over and above baseline, in response to market demand and backed by User commitment
Incremental NTS Entry Capacity (non-obligated) – at its discretion, National Grid can release additional firm NTS Entry capacity at an ASEP, over and above obligated levels.
Interruptible NTS Entry Capacity is made available to the market at ASEPs where it can be demonstrated that firm NTS Entry Capacity is not being utilised. The volume of Interruptible NTS Entry Capacity available at an ASEP consists of 2 parts:
Use it or Lose it (UIOLI) – any NTS Entry firm capacity that has been unutilised over recent days, can be resold to the market as Interruptible NTS Entry capacity.
Discretionary - National Grid can make additional interruptible NTS Entry capacity available to the market at its discretion.
If there is physical congestion on the network, then National Grid may curtail Interruptible NTS Entry Capacity rights, without any compensation for the Users affected.
If a User's flow exceeds their NTS Entry Capacity entitlements for any given gas day, then a shipper will incur NTS Entry Overrun charges. The overrun charge is the shipper’s financial incentive to buy all the capacity that it needs.
Once a shipper has obtained a shipper licence then they can be considered a ‘User’ of the NTS under the terms of the Uniform Network Code (UNC). Shippers can obtain entry capacity by making bids on the Gemini system through a number of auctions. These bids are allocated or rejected in accordance with UNC, and with consideration to National Grid’s incentive schemes.
National Grid NTS will monitor Users’ utilisation of their Available System Capacity at Interconnection Points (IP(s)).
After each 6 month period, consisting of 1 April to 30 September and the 1 October to 31 March, National Grid NTS will then, in accordance with the principles set out in the CMP LTUIOLI Guidance Document, identify whether or not a User(s) at an IP has underutilised its Available System Capacity and provide notification to that User of its utilisation.
LTUIOLI Guidance Document - Final
LTUIOLI Guidance Document - Marked up