Offtake Arrangements Document
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Offtake Arrangements Document. 25 th February 2011. Revisions to Offtake Profile Notices. 4 hours notice is required if the flow rate change at an offtake is not less than 50% of the Maximum Flat Offtake Rate (MFOR), 1/24th of the Maximum Daily Quantity - PowerPoint PPT Presentation
Transcript of Offtake Arrangements Document
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Offtake Arrangements Document
25th February 2011
Revisions to Offtake Profile Notices
4 hours notice is required if the flow rate change at an offtake is not less than 50% of the Maximum Flat Offtake Rate (MFOR), 1/24th of the Maximum Daily Quantity
2 hours notice is required if the flow rate change at an offtake is less than 50% but not less than 25% of the MFOR
1 hour notice is required if the flow rate change at an offtake is less than 25% of the MFOR
1 hour notice is required when there is a decrease in rate of offtake
Revisions to Offtake Profile Notices
The minimum notice required if there is a change in the aggregate rate of offtake to an LDZ is 2 hours
The aggregate flow rate change shall not exceed 5%
A revised Offtake Profile Notice (OPN) must not be submitted more frequently that once in each hour
A revised OPN must not be submitted later that 04:00 on the gas flow day
Low Demand Days
If at the 13:00 preceding day demand forecast the demand for an LDZ is less than 50% of the 1 in 20 peak day, NTS can declare a low demand day prior to 17:00 on the preceding day. If this is declared the DNO is required to flow at a flat profile. A revised OPN can be submitted to reflect changes in the forecast LDZ demand.
Offtake Tolerances
The tolerance for an offtake is 10% of the prevailing offtake rate. The tolerance in aggregate for all offtakes is 3% of the aggregate prevailing offtake rates.
Pressure
The DNO shall submit a pressure request for each offtake when submitting the initial OPN for the day. A revised pressure request can be sent up to but not after 24:00 hours on the day. In agreeing a pressure the NTS will consider the safe and efficient operation of the NTS and the DNO will consider the safe and efficient operation
of the LDZ.
TPD – User Offtake Obligations
The maximum permitted rate in respect of an NTS LDZ offtake is a rate calculated as:
(Flat Capacity / 24) + (Flexibility Capacity / 4)
NTS will not be obliged to make gas available for offtake in the period between 06:00 and 22:00 hours on any day in a quantity which exceeds
(Flexibility Capacity) + (16/24 * Daily Quantity)
Issues
All offtakes, regardless of their mode of operation (volumetric or pressure controlled) and booked MDQ, are treated identically in terms of changes to flow rates.
Offtake tolerances are breached in the first and last hours of the gas day for volumetric offtakes due to gas demand changes.
NTS could declare a low demand day for 6 months of the year in a seasonally normal demand year if they wished to do so.
Pressure requests are required for all offtakes regardless of their criticality to the NTS or to the DNO.
Issues
The NTS can request a lower pressure at an offtake that meets the safe and efficient rule but causes the DNO to operate a different offtake in the same LDZ above the booked MDQ. This can also cause breaches to offtake flow rate and OPN tolerances
Clarification of flow swap rules
Potential Modifications
Applicable Rule Ability to Comply Modification Required
4 hours notice is required for an offtake flow rate change of not less than 50% of the MFOR
Yes - For volumetric and large pressure controlled offtakes
No - For small pressure controlled offtakes
Yes - Exempt small pressure controlled offtakes from the flow rate notice period rules
2 hours notice is required for an offtake flow rate change of less than 50% but not less than 25% of the MFOR
Yes - For volumetric and large pressure controlled offtakes
No - For small pressure controlled offtakes
Yes - Exempt small pressure controlled offtakes from the flow rate notice period rules
1 hours notice is required for an offtake flow rate change of less than 25% of the MFOR
Yes - For volumetric and large pressure controlled offtakes
No - For small pressure controlled offtakes
Yes - Exempt small pressure controlled offtakes from the flow rate notice period rules
1 hours notice is required for a flow rate change when there is a decrease in the rate of offtake
Yes - For volumetric and large pressure controlled offtakes
No - For small pressure controlled offtakes
Yes - Exempt small pressure controlled offtakes from the flow rate notice period rules
Potential Modifications
Applicable Rule Ability to Comply Modification Required
The minimum notice required is 2 hours when there is a change to the aggregate LDZ offtake
Yes - Except when large weather forecast errors occur
No – the rule however needs clarification as it can be interpreted as an initial 2 hours notice period but only 1 hours notice subsequently required
The aggregate flow rate change shall not exceed 5%
Yes - Except when large weather forecast errors occur
No
A revised OPN is not submitted more frequently than once per hour
Yes No
A revised OPN is not submitted later than 04:00 in the gas day
Yes No
Potential Modifications
Applicable Rule Ability to Comply Modification Required
If a low demand day is declared by NTS a DNO must flow at flat profile
Yes - Although the NTS can declare a low demand day for 6 months of the year in an average SND year
Yes – If the threshold is reduced from 50% of the firm peak day to 25% the 6 months is reduced to 3 months
Offtake tolerances – for an offtake 10% of the prevailing offtake rate
Yes - For volumetric and large pressure controlled offtakes although not in the first and last hours of the gas day
No - for small pressure controlled offtakes
Yes - Exempt small pressure controlled offtakes from the flow rate notice period rules and exempt the first and last hours of the gas day from the rule
Offtake tolerances – for the aggregate of all offtakes 3% of the aggregate of the prevailing offtake rates
Yes Yes - Exempt the first and last hours of the gas day from the rule
Potential Modifications
Applicable Rule Ability to Comply Modification Required
Revised Pressure Requests – reach agreement on a pressure that may be different from the assured pressure
Yes – Although a lower offtake pressure request from the NTS may cause a breach in the MDQ of other offtakes in the same LDZ
Yes – MDQ breaches caused by NTS pressure requests are exempt from the consequences of an MDQ beach or a capacity swap is allowed. Alternatively an NTS request can be refused by a DNO if a MDQ breach may occur. Reach agreement on a list of critical offtakes by the DNO and the NTS and only agree pressures for these offtakes.
Potential Modifications
Applicable Rule Ability to Comply Modification Required
The maximum permitted flow rate for an offtake is 1/24th of the MDQ + ¼ of the booked flexible capacity
Yes No
Between 06:00 and 22:00 NTS are only obliged to make 16/24th of the daily quantity + the flexible capacity available
Yes No
