4. Consumption and supply one year ahead (winter outlook)
4.3 Emergency supply
Energinet.dk is responsible for security of supply in Denmark in keeping with the executive order on maintaining security of natural gas supply. This section describes the rules which will be applicable in winter 2010/2011. Section 1.4 specifies the changes resulting from the new emergency supply regulation.
Energinet.dk’s emergency preparedness planning is designed to handle a number of supply failure situations and where the worst-case scenario is a failure in the supply from the Tyra-Nybro pipeline.
4.3.1 Tools
In case of serious disruptions, Energinet.dk can maintain the gas supply to Denmark using a series of tools which compensate
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Table 4.2: Emergency supply requirements for two months.
*Model estimate with uncertainty subtracted
1 March Million Nm3
60-day requirement in the exit zone
before interruption Approx. 900*
Expected interruption at interruptible
consumption sites Approx. 150
60-day requirement in the exit zone after interruption Approx. 700
Supplies from Syd Arne Approx. 400
Supplies from Germany Approx. 50
Emergency storage and filling requirements
in the storage facilities Approx. 300
for the failing supplies from the Tyra pipeline and reduce the need for gas:
• Supplies from the Danish gas storage facilities
• Emergency supply from the Tyra field via the Harald field through the Syd Arne-Nybro pipeline
• Interruption of the largest gas consumers – interruptible emergency supply
• Use of linepack in land-based pipe-lines and offshore pipepipe-lines.13 In addition, there is a limited option of supplies from Germany via the DEUDAN pipeline.
Energinet.dk establishes the required use of the above tools based on two dimensioning situations:
• 36-hour interruption of supplies at extreme temperatures (20-year winter)
• 60-day interruption of supplies at normal winter temperatures.
Each year, Energinet.dk calculates the expected consumption in the dimen-sioning situations and plans the use
13 At a given pressure, there is a volume of gas in the gas pipelines. If a lower pressure is acceptable, the gas volume in the pipelines must be smaller to maintain this pressure. The difference between the gas volume at the high and the low pressure is called the linepack.
of the tools accordingly. For winter 2010/2011, emergency supply require-ments and the contribution of the individual tools have been calculated as follows:
Storage services
Energinet.dk reserves a total storage volume, of which a small part is reserved for system balancing. For winter 2010/2011, Energinet.dk has reserved a total storage volume of about 250 million Nm3, of which 35 million m3 are reserved for system balancing. In addition, the majority of the volume capacity in Stenlille and Lille Torup has been sold subject to so-called filling requirements. This means that the storage customers commit themselves to maintaining a certain stock volume, so that Energinet.dk, in emergency supply situations, will have access to additional gas volumes in the storage facilities. The degree of required storage filling varies during the winter.
The reservation of storage volume is based on the requirements in the two dimensioning emergency supply situations related to the expected supplies from the Syd Arne pipeline, imports from Germany and interruption of the consumption sites with interrupt-ible emergency supply.
For the purpose of handling short-term interruptions of supplies from the North Sea in extreme winter temperatures, Energinet.dk has reserved withdrawal capacity from the storage facilities to compensate for the lack of supply.
Moreover, Energinet.dk can make use of the limited gas volumes which are stored in the actual gas pipelines – the so-called linepack.
The reserved withdrawal capacity at the two storage facilities is distributed differently over the year.
Supplies from Syd Arne
Energinet.dk has signed an emergency supply agreement which paves the way in emergency supply situations for supplies of 7 million Nm3/day from Tyra via Harald through the Syd Arne-Nybro pipeline for the Danish market.
Usually the gas flows via the Harald pipeline from the Harald field to the Tyra platform where it is processed before being sent ashore via the Tyra pipeline.
In an emergency supply situation, gas would have to flow in the opposite direction in the Harald pipeline and be sent onshore via the Syd-Arne pipeline.
In this situation, supplies from the Syd-Arne field and the Harald field are expected to stop since pipeline capacity
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Table 4.3: Emergency supply categories in new emergency supply concept.
Category Terms and conditions
Firm emergency supply Firm (60 days’) emergency supply Full insurance
36-hour interruptible
emergency supply In case of 36-hour interruptible emergency supply, the gas offtake at the consumption site must be reduced within 36 hours of an emergency supply situation being declared. Consumption must not be resumed until the emergency situation ends.
Hyper-interruptible
emergency supply In case of hyper-interruptible emergency supply, the gas offtake at the consumption site must be reduced within three hours of an emergency supply situation being declared and must not be resumed for 72 hours
is limited and supplies from the Tyra platform will take up the capacity.
Interruptible emergency supply (emergency supply concept)
Energinet.dk’s concept for interruptible emergency supply allows the largest consumption sites to opt out of the statutory emergency supply ‘insurance’.
In this context, the largest consumption sites are those with annual gas con-sumption exceeding 2 million Nm3. Under the emergency supply concept, Energinet.dk offers three categories of emergency supply as illustrated in Table 4.3. The three categories can be combined into partially interruptible emergency supply where the consumer must be able to reduce some of its consumption within three or 36 hours.
This implies that part of the offtake is hyper-interruptible (interrupted within three hours), another part constitutes 36-hour interruptible emergency supply, while the rest is firm emergency supply.
By combining the three categories, the degree of ‘insurance’ may be composed to match the individual consumption site. This ensures flexibility in relation to the interruptibility of consumers.
In emergency supply situations, consum-ers that have entered into a contract on interruptible emergency supply with Energinet.dk are handled in cooperation between the distribution companies and Energinet.dk.
When Energinet.dk assesses that an emergency supply situation exists, Energinet.dk will issue an emergency supply statement to the interruptible consumers as well as to the TSOs in Swe-den and Germany, the two storage companies and the upstream pipeline operator.
In the following hours, Energinet.dk will monitor the offtake of the interruptible consumers. If the offtake is not reduced, the interruptible consumers will be con- tacted with a view to interrupting supply.
Customers with hyper-interruptible sup-ply as well as customers with 36-hour interruptible supply that fail to interrupt their offtake under the interruptibility agreements made will be interrupted physically by the distribution company at the request of Energinet.dk.
Other tools, including supplies from Germany
In addition to the alternative gas supplies available to Energinet.dk,
Energinet.dk has made cooperation agreements with the neighbouring TSOs, thereby ensuring the required operational flexibility.
Initially, supplies from Germany via the DEUDAN pipeline will take place on a commercial basis if there is a physical flow towards Germany and thus the possibility of backhaul (or back flow).
From October 2010, it will also be possible to physically supply up to 200,000 Nm3/h of gas from Germany to Denmark. In normal situations, this option will, in some periods, be limited by the pressure requirements of the Danish system, but in an emergency situation the pressure in the Danish system will, after a period of time, be so low that gas can flow from Germany to Denmark. Alternatively, physical flow from Germany is secured by closing the southbound valve in Egtved so that the south Jutland part of the Danish gas sys-tem is controlled from Germany, and gas with a German calorific value is restrict-ed to this area. Energinet.dk cooperates with the German TSOs to identify options and ensure the necessary, commercial agreements on gas supplies to the Danish system. See section 1.3.
In an extreme scenario where an event or a combination of events causes a
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more severe supply situation than the emergency preparedness is designed to handle, the provisions on force majeure in the Rules for Gas Transport will come into force. This implies, for instance, that general provisions regarding firm emer-gency supply will be inoperative and that Energinet.dk can make a prioritised interruption of consumers based on overall system requirements, taking ac-count of the necessary consumption.
4.3.2 Prioritisation of means
The Rules for Gas Transport contain a number of conditions which ensure that, in certain situations, Energinet.dk can influence or make arrangements for the supply and consumption of gas to optimise security of supply and the gas system. This applies to interruptible consumers, reduced nomination, reduced capacity, emergency supply and force majeure.
Any decisions concerning the means by which Energinet.dk secures supplies are based on the premise that the effects of any technical problems on the market should be minimal. The specific supply and weather situation and the actual status of the gas system are important parameters for the timing and sequence of use of the various means, for which
reason it is not possible to detail in advance when and how the individual means must be used.
In the event of major interruptions of supplies from the North Sea, a number of measures will be taken to ensure supplies to the Danish gas market.
The means are described above.
In an emergency situation, Energinet.dk takes over all transport of gas in the system. Energinet.dk’s emergency supply obligations apply only to the Danish gas market, but in so far as shippers ensure the availability of gas for transit at the entry points or from storage facilities, Energinet.dk will seek to make the necessary transport capacity available if the physical conditions so permit.
As described in the Rules for Gas Trans-port, Energinet.dk must, in the event of an emergency situation, distribute avail-able gas volumes in the Danish gas mar-ket, giving due consideration to:
• Concluded agreements on emergency supply in accordance with the emer-gency supply concept, see section 4.3.1
• The consequences for consumers must be minimised to the greatest possible extent, preferably by not interrupting supplies to consumers sensitive to ir-regularities in the supply of gas.
In this context, it should be pointed out that shippers and storage customers must, if possible, continue supplying gas to the Danish gas system at the entry points and the storage facilities.