Firm capacity

The volume of firm capacity made available at each offtake point consists of the following amounts:

• Baseline exit capacity (obligated) – as defined by our Gas Transporter Licence;
• Incremental exit capacity (obligated) – firm capacity made available over and above baseline, in response to market demand and supported by user commitment. This increase in capacity is permanent; and
• Incremental exit capacity (non-obligated) – we can release additional firm capacity at an offtake point over and above obligated levels.

Off-peak capacity

Off-peak capacity can be made available to the market at offtake points where firm capacity is not being used. The volume of off-peak capacity available at an offtake consists of three parts:

• Use It Or Lose It (UIOLI) – any firm capacity that hasn't been used over recent days can be resold to the market as interruptible capacity;
• Unutilised Maximum Network Exit Point Offtake Rate (MNEPOR) – during D-1 at 13:30, the NTS demand forecast is published. Where this demand forecast is less than 80% of the annual peak 1-in-20 demand forecast, we are obliged to release any remaining capacity up to the MNEPOR level as off-peak capacity; and
• Discretionary – we can make additional off-peak capacity available to the market at our discretion.

If there are low pressures on the network, we may curtail off-peak capacity rights, without any compensation for the users affected.

Long-term GB auctions

There are three types of long-term GB exit capacity auctions:

• Enduring Annual Exit (Flat) Exit Capacity (EAFLEC) Increase - This application window is for capacity covering the period Y+4 to Y+6. The capacity bought in this application window is enduring and can be increased or decreased in a later application window (subject to user commitment). The application period for this auction is 1 to 31 July where the bid window will be open from 8am to 5pm on each business day.
• Enduring Annual Exit (Flat) Exit Capacity (EAFLEC) Decrease - This allows a user to decrease their enduring capacity holdings from Year Y+1 (October following the July window). Further decreases and increases can be requested in subsequent application windows. The application period for this auction is 1 to 15 July where the bid window will be open from 8am to 5pm on each business day.
• Annual NTS (Flat) Exit Capacity (AFLEC) - This is for capacity covering the period Y+1 to Y+3. The capacity allocated in this application window is not enduring and therefore cannot be increased or decreased. If capacity is requested in this application window for Y+2, in the following year's application window the capacity will show as Y+1 and any further annual capacity requested will be in addition to the original Y+2 capacity. The application period for this application window is 1 to 31 July where the bid window will be open from 8am to 5pm on each business day.

All submitted requests are subject to analysis by us. Successful applications submitted in the AFLEC window will be allocated within ten business days of the application window closing. Successful applications submitted in the EAFLEC window will be allocated on or before 30 September.

The unit price (p/kWh) for capacity bought in both AFLEC and EAFLEC auctions is published on the Joint Office of Gas Transporters website. All conditions and requirements for all of the above mentioned application windows can be found in UNC Transportation, Section B, Sub Section 3

Long-term EU auctions

There are three long-term EU auctions that are held for firm exit capacity. These are as follows:

IP Annual Yearly Exit Capacity (IPAYNEX)

Held on the first Monday of July each year for the sale of firm capacity whereby, 15 transactional periods are auctioned off.

IP Annual Quarterly Exit Capacity (IPAQNEX)

Held on the first Monday of August, November, February and May of each year for the sale of firm capacity. A decreasing number of transactional periods, starting at 4 and moving downwards, are auctioned off.

IP Rolling Monthly Exit Capacity (IPRMNEX)

Held on the third Monday of each month* for the sale of firm capacity whereby, one transactional period is auctioned off.

For more information relating to Long-term IP auctions, please visit the PRISMA FAQs webpage or contact the PRISMA helpdesk at: [email protected].

*subject to EU Bank Holidays where the Auction opening date may be subject to change; please reference the ENTSOG calendar here https://www.entsog.eu/capacity-allocation-mechanisms-nc#cam-nc-early-implementation-documents-and-auction-calendar

Short-term GB auctions

There are two GB auctions that run daily for the sale of firm exit capacity. Bids may be evergreen or reducing. An evergreen bid remains fixed throughout the day. A reducing bid reduces by 1/x with each hour that passes where it remains unallocated (where x is the number of hours remaining in the gas day at time the bid was placed).

There is also one auction that runs daily for the sale of off-peak capacity. All these are detailed below:

Day-Ahead Daily Exit Capacity (DADNEX)

Unsold obligated firm exit (flat) capacity will be made available in the DADNEX auction and is a 'pay as bid' auction.

Bid Window: D-7 05:00 to D-1 14:00

Allocation Window: D-1 15:00 to D-1 16:00

Charges: For information, please refer to the Joint Office website

Within-Day Daily Exit Capacity (WDDNEX)

Any remaining unsold capacity after the allocation of the DADNEX auction will roll over and be made available in the WDDNEX auction, which is a 'pay as bid' auction.

Bid Window: D-1 14:00 to D-0 02:00

Allocation Window: D-0 06:30 to 02:30

Charges: For information, please refer to the Joint Office website

Daily Off-Peak Exit Capacity (DONEX)

In addition to firm NTS exit (flat) capacity, users may also bid for and purchase daily off-peak exit capacity. This product is sold via the DONEX auction. This amount depends of the prevailing forecast total system demand for the gas day being less than 80 per cent of the 1-in-20 peak day demand.

Bid Window: D-7 05:00 to D-1 14:00

Allocation Window: D-1 15:00 to D-1 16:00

Charges: For information, please refer to the Joint Office website

General Pricing

All auction bids will be allocated based on price (highest first) until all unsold capacity has been allocated (in line with the allocation principles as described in UNC Section B – Annex B1). Where bids exceed the available unsold quantity, National Gas may allocate these but will do so at their own discretion.

Short-term EU auctions

There are three short-term EU exit auctions:

IP Day-Ahead Exit Capacity (IPDADNEX)

Held day-ahead (D-1 15:30) for the sale of firm capacities.

IP Within-Day Exit Capacity (IPWDDNEX)

Held on the day (D-1 18:00) for the sale of firm capacity.

IP Daily Off-Peak Exit Capacity (IPDONEX)

Held day-ahead (D-1 16:30) for the sale of off-peak capacities.

For more information relating to Long-term IP auctions, please visit the PRISMA FAQs webpage or contact the PRISMA helpdesk at: [email protected].

Past application data

We make previous auction details and results available online.