Question 1 - To NRAs
Question 2 - To NRAs
Question 3 - To TSOs (NRAs are welcome to provide response)
Question 4 - To TSOs and NRAs
Question 5 - For TSOs and NRAs in Member States (MS) where gas is odourised at TSO-level
Question 6 - For TSOs and NRAs in MSs where gas is not odourised at transmission level which border MSs where gas is odourised at transmission level
Question 7 - For TSOs and NRAs in MSs where gas is not odourised at transmission level which border MSs where gas is odourised at transmission level
Question 8 - For TSOs and NRAs in MSs where gas is not odourised at transmission level which border MSs where gas is odourised at transmission level
Question 9
Question 10
Question 11
Question 12
Question 13
Question 14 - For NRAs
Question 15 - For NRAs
Question 16 - For NRAs
Question 17 - For NRAs
Question 18 - To NRAs


Cooperation Agreement between German network operators (current version 29 June 2012)

esp. §§ 22-27 and §§ 50-60​ set out out content elements of IAs. Some TSOs have published template IAs on thier websites.

Generally the mangement of gas quality specifications works well at German IPs, so gas can flow without barriers.

However it seems that the narrow British gas quality specs have a knock on effect throughout continental gas networks and require active gas quality management measures in certain circumstances.​

In general, a criteria could be that the barrier should be addressed at those IPs where the narrowest gas spec has its origin.

The German gas quality specification range (as estabnlished in DVGW technical rule G 260) is expected to be wide enough to accommodate any ​gas quality that could pop up in Garmany in the next ten years.

At IP Medelsheim/Obergailbach​:

 physically gas cannot flow into the German network, commercially it is possible by virtuals backhaul up to the nominated forward flow


Currently there seems to be no relevant interest to physically flow gas from France to Germany.

According to public sources (GRTgaz 10 year plan) it is considered to enable the physical flow of ​non-odorised gas via Medelsheim/Obergailbach as of 2017. 

BNetzA is not in the position to estimate the costs of the different solutions. Given the above planning, the issue will be resolved anyway​.

(e)Other(please specify)2354

For the German networks no systematic study exists.

Given the above planning, the issue will be resolved anyway​.

Given the above planning (see question 7), the issue will be resolved anyway​.​

For the German networks no systematic study exists. The acceptebale level of odourant has to be looked at before deodourised gas enters the German network from France.

Due to the fact that gas is not odourised on the transmission level, turbines, industrial applications and storages are not adjusted to the respective odourant.​

Please refer to TSO answer.​

The technical rules DVGW G 260 and 280 foresee that the TSO level is non-odourised.​

Deodourised gas has to be conform to the same technical standards as non-odourised gas and is not generally excluded.​

Research led to DVGW technical standard G 290.​

Yes, no odourisation on transmission level.

Units are not fixed in national law/regulation but in (technical) standards (DIN - Deutsches Institut für Normung and DVGW)​


In section 4.8 of the royal decree of 23 December 2010 on the code of conduct for access to the natural gas transmission system, the storage and lng facilities and amendment of the royal decree of 12 June 2001 on the general conditions for natural gas supply and the conditions for granting of natural gas supply licenses (BS 05/01/2011), the following is stipulated:

Art. 166 §1 The transmission system operator aims at executing interconnection agreements with the other operators and the adjacent system operators.
§2 This interconnection agreement shall contain amongst others:
1° the mutual obligations of the operators for the provision and exchange of the necessary information for the safe and efficient transport of natural gas on the transport systems;
2° the method for and the accuracy with which the metering is performed, and the agreements regarding the quality control on these meterings;
3° the method enabling the involved shippers to evaluate the metering method and results;
4° mutual obligations of the operators for the provision of metering data to each other and to the involved shippers;
5° the mutual criteria for pressure, temperature and quality of natural gas that the operators of the adjacent transport facilities must comply with as supplying transport companies when injecting natural gas in the natural gas transport system; 
6° the procedures and rules for nomination, re-nomination, allocation and data exchange;
7° the rules for allocation of natural gas at the interconnection point and allocation in case of unavailability of metering data;
  provisions regarding the use of an operational balancering agreement (OBA);
  provisions regarding a minimum natural gas flow, change to the rate and direction
of the natural gas flow and how this is communicated to the shippers;
10°   the mutual agreements with a view of guaranteeing the network balance;
11°   the mutual agreements regarding maintenance planning and execution;
12° the mutual agreements regarding incident management and emergency situations;
13° the mutual liabilities.
§3 Changes to the interconnection agreement that have consequences for the shippers shall be submitted to them in advance for consultation.


Limits in Belgium have been set to coop with supplies coming from different sources. These are broad limits not to jeopardize the gas entering Belgium from our neighboring countries. However, as a lot of these gas is also transiting the country, the acceptability of the gas to the other country had to be taken into account. As long as the flow was route specific, this was straightforward. But since entry/exit decoupled the entries with the exits, more insecurity has been introduced, which is to be dealt with by the TSO as far as they can. Whenever the limits are more stringent on the other side, a potential barrier is identified for gas that wants to leave the country. In this respect, capacity conditional to the right gas quality specfication has been offered, to allow the TSO to deal with this situation. This is especially true for the Belgian – UK  direction on Wobbe. The degree of capability of the TSO to facilitate the gas flow, is one trigger to define the need for a solution, market demand is an other.

Discussions in Belgium around the TYNDP have always taken into account gas quality issues, in a surge for opportunities to let these issues being facilitated by the TSO.

In Belgium, odorisation takes not place at the transmission level.

(a)  For the borders, where the odorisation practice differs, e.g. IPs with GRTgaz and Creos: physical entry flow is not possible, but commercial flow (backhaul) is possible;
(b)  Physically: Belgium is highly interconnected with several adjacent TSO's in the East, North and West, and these TSOs do not accept odorised gas or gas containing traces of odorant.  Therefore no physical flow of odorised gas is allowed into the Fluxys-grid ; 
(c)  At Blaregnies, the IP with GRTgaz, technically fysical reverse flow would be possible for up to 300.000 Nm³/h if the odourisation practice would be aligned;


Yes. CREG is not aware of any cross-border trade related problems that were brought to our attention by network users, but the problem was avoided by France to allow, when deciding on the project of the Dunkerke terminal, to build a direct line for the export of non-odourised gas towards Belgium. This opens the door for swap possibilities in France. Traditionally speaken, gas supply in Belgium did never come from the south.


Although intermediate steps to come to this situation might be important to mention, like swap agreements.

(b)Full non-odourisation of transmission network in the EU2134

No studies have been performed to our knowledge.


If France becomes a net exporter, flow from France to Belgium (and Germany) will be hampered.

No studies have been performed to our knowledge.

'Gas should not be odourised:

- impact of odorants on some chemical industry processes
- today different odorants are used at distribution level and in different countries. These odorants seem not to be compatible with each other
- much higher volumes have to be odourised because not only distribution quantities have to be odourised but all quantities
Different protective and safety measures exist on transmission level compared to distribution level, because of difference in material, pressure level, zonal and human protection which keeps the transmission as far as possible away from urban areas (in contrast to distribution).


To our knowledge, no research have been performed.

No rules exist.

No rules exist.

To our knowledge, no research have been performed.

Yes. Fluxys and IUK have the same approach to odourisation.

No specific reference is made to the use of units in legislation.


​No, there are not any related rules.

​No barrier has benn identified.

(a)Increased transparency and TSO cooperation1111

​There is no odourisation at transmission level

There is just one TSO in the Czech Republic.


There are no specific national regulations regarding cooperation between TSOs and the content of interconnection agreements.


In Spain, the interconnection agreements among TSOs are not regulated. In some cases the agreement form is published. The main Spanish TSO is also the technical system management, who is the responsible for the coordination among TSOs.

 In relation to limits set in gas quality specifications, there is no particular barrier identified to physically move the gas in both directions at the IPs.


Furthermore, currently the three countries have different odourisation practices and gas quality specifications.
Spain receives gas through pipeline from Morocco, Algeria, Portugal and France.
So far, the gas flows among these countries have no presented any particular problem. Gas must comply with gas quality specifications at national level.  
In France, for instance, it will decide to eliminate odourisation in the transmission networks, the problem would need to be addressed.


TSOs and network users shall comply with gas quality provisions according to the above mentioned Royal Decree 1434/2002, 27th December.

 We are used to handle different gas qualities already since we receive LNG from all over the world. We have not had any problem so fat users comply with gas quality specifications.


Specific measures are not in place. So far, bilateral meetings between TSOs and network users take place in order to share information regarding future gas quality specifications.




In Spain, gas is odourised at transmission level using Tetrahydrothiophene (hereafter THT) where 15 mg THT/m3 is added. Also, 7 mg THT/m3 is added at distribution level. The final concentration is 22 mg THT/m3 (8 mg S/m3).

The gas received from Morocco and Algeria is non-odourised. The contractual and technical rules have been established by bilateral agreement to import gas. Once in the national system, gas is treated to adapt it to quality requirements.

The odourisation takes places at transmission level in France. The contractual and technical rules have been established by bilateral agreement to move gas in both directions.
The French limit of odorisant concentration is higher (25 THT/m3) than Spanish. Therefore, a dose of THT needs to be added at the interconnection point to move gas from Spain to France. 

(a)Increased transparency and TSO cooperation1111

The mentioned Royal Decree 1434/2002, 27th December, on the regulation of transmission, distribution, trading, supply and procedures of gas infrastructure permissions.

 In his Chapter X, Quality on gas supply, the article 63 Gas quality, reads as follows:

“Gas quality levels regarding composition, calorific values and other product characteristics, to supply, are those included in H group, second family, according to gas classification set up in UNE-EN-437, and they shall comply with provisions established in Technical Management of the Gas System Regulations (NGTS in Spanish)”.

 In particular, NGTS-5 Measurement, and PD-01 (Detailed Procedure), approved by “Resolución” of Ministry of Industry, Energy and Tourism on 22 september 2011: Measurement, quality and odourisation of gas.

 There are no specific provisions regarding non-odorised gas and a de-odourised gas.

So far, we are not aware of any study about “masking effects” at national level.

Yes, every TSO follows the same odourisation approach at national level.


Regarding contractual relations between system operators, the law is mainly focused on the interface between transport & distribution. In this framework, a contract between a TSO and network user has to contain the following aspects:
·         General terms and conditions to use the network (detailed)
·         Entry and Exit points, transported gas volumes and capacities required
·         Services fees
·         Invoicing conditions, payment conditions
·         Bank guarantee
·         Termination conditions
No special rules for cross-border interconnections.



It is TSOs task and responsibility.
In general:
Prescription of gas quality in some neighboring countries is stricter than the one in Hungary. For this reason FGSZ is able to receive gas from abroad but due to the blending of different gas quantities from different sources in the network, since the TSO is unable to influence/modify the actual gas quality, it may cause a barrier in case of flow from Hungary to third countries. Usually the sulfur content and the water dew point are these barriers. Criteria to be considered are the following: does it affect security of supply, where in the gas value chain changes and issues appear, can the CAPEX be justified by the potential benefits, how the final solution should be spread between the supply chain in line with the justified responsibilities and technical possibilities? The beneficiary pays principle should always apply.
Gas quality specifications:
In the Government Decree No 19/2009 (I. 30.) on the implementation of the Act on Natural Gas Supply (Vhr.), attachment 11.
Vhr. Article 89
(4) The detailed rules of managing departures from the guaranteed quality shall be laid down in the Network Code.
Network Code (, Procedure in case of feed-in of off-standard quality gas)
a)         The system user is responsible to adhere to the requirements in article 4.2 concerning the quality of the natural gas fed in into the grid. Such responsibility prevails also in case of full or partial island-mode operation.
b)         If the quality of the gas fed in does not comply with the requirements in article 4.2 the TSO shall notify in writing the system users and the gas producer affected, on the fact of off-standard quality gas fed in into the grid. If, as a consequence of that, the system user indicates its intention to re-nominate the TSO shall accept such re-nomination marking such re-nomination with the reason of ‘feed-in of off-standard quality gas’.
c)         If the system user does not indicate its intention to re-nominate or does not reduce its feed-in of off-quality gas to the extent which results in cessation of feeding-in off-quality gas by the end of the gas day the TSO shall interpret such behaviour as insistence upon feed-in of such off-quality gas. If so, all damages arising of the feed-in of off-quality gas is to be borne by the system user and the business partner operator in fault.
d)         The TSO sends the re-nominations to the business partners for match check with the remark that the nomination cut in accordance with article c) above makes the system user exempt, if the same communication was made towards the producer business partner. If the producer system user does not cease its feed-in of off-standard gas any compensation of damages beyond the extra system usage charge is subject of a law suit in accordance with the Civil Code. All damages arisen from the feed-in of off-standard gas are to be borne by the producer business partner.
e)         The TSO may deny the off-take of non-standard quality gas from the producer system user.


Currently the framework to cope with barriers on IPs  is established at each individual IA but this may not in all cases sufficiently solve the problem. In certain cases the guaranteed quality of import and indigenous input gas might be necessary throughout Europe regardless the origin of gas. This guarantee may only be ensured by significant additional investment into gas treatment plants. Such investments possible for the intended purpose may not be justified/ without a CBA analysis.

Review on other actions above the existing regulations are not intended, the present ones are adequate.

The contracts enforce FGSZ to deliver NG to other states without odorization.

If a central odorization system is operated at one side of the IP and it has to change the direction of gas flow, it can cause barrier (Mosonmagyaróvár).

(a)Increased transparency and TSO cooperation1111

There is a feasibility study to modify the central odourisation system in region of Western Hungary. Scenarios: central or local odorisation All scenarios were investigated as full, immediate changes



There is no safety or other technical reason to do the odourisation at transmission level, only applicable regulation and cost efficiency considerations play a role

At the time (early nineties) of introducing the currently used odorant such research was carried out on TSO level. At the same time the odorant from Ethil mercaptan was switched to 50% Tetra Hidro Tiofen + 50% Tercier Butil Mercapthan.


Yes, in the Government Decree No 19/2009 (I. 30.) on the implementation of the Act on Natural Gas Supply (Vhr.).
Vhr. Article 89
(4) The detailed rules of managing departures from the guaranteed quality shall be laid down in the Network Code.
Vhr. Article 103
(1) The natural gas injected into transmission and distribution lines must be odorised.
(2) Except in the case, the responsibility for the odorisation of natural gas shall lie with the transmission system operator.
Network Code (6.9 Odorization)
a)         According to the VHR and with the exceptions defined therein, the odorization of the natural gas is the obligation of the TSO. In case of direct feed-in into the transmission and the distribution network the odorization may be done by the producer on the basis of a contract or, in the lack of such contract it is done by the TSO.
b)         In the transmission system the odorization is done by the TSO in accordance with the prevailing norms and Network Code at the off-take points of the grid.
c)         The injection of the odorization material is performed by the TSO in centrally or locally installed odorizers.
d)         The amount of odorizing material is controlled and recorded by each odorizer. The odor level in the interconnected gas grid is checked and recorded according to the Hungarian Norm MSZ-09-74.0011 by the partner system operator too. The distribution operator is obliged to ensure the check and recording of the odor level and the transfer of such data to the TSO.
e)         The TSO is obliged to regularly check by measurements the appropriateness of the odor level at the designated points of the transmission grid.
f)         The flow-proportional odorization is done by the TSO in accordance with the winter and summer odorization norms. Such seasonal norms are specified in the Grid Code.
g)         Any level of odorization other than specified in the Grid Code i.e. from an interconnected system is to be published by the TSO on its home page among the Quality Accounting Rules.

The regulations focus on the odorized gas only. The odorization of gas that exits in FGSZ system for domestic usage is obliged.

At the time (early nineties) of introducing the currently used odorant such research was carried out on TSO level. At the same time the odorant from Ethil mercaptan was switched to 50% Tetra Hidro Tiofen + 50% Tercier Butil Mercapthan.



Units are in use in  daily external communication and public information


Currently:     - m3 (15 ºC); 
                      - MJ (15/15 °C) based of NCV (Normal Calorific Value)
     Energy content:          Joules (and multiples)
     Calorific value -    Mega-joules per cubic meter
      Wobbe index  -  Mega-joules per cubic meter
      Pressure:  Bar,   Absolute pressure


      Temperature:   Degrees Celsius


Polish national regulations don’t specify the content of interconnection agreements.

There are no potential barriers, related to gas quality, identified up to now at IP’s at Polish borders

There are no potential barriers, related to gas quality, identified up to now at IP’s at Polish TSO’s grid borders

The scope of acceptable gross calorific value (GCV) in Polish TSO’s grid and Polish regulations is similar to European standards related to gas quality (i.e. EASEE-gas). We do not expect any problems related to different GCV or another quality parameters at IP’s on Polish TSO’s grid borders

These questions do not refer to Poland. Polish TSO does not transmit odourised gas to other MSs and we do not have interconnection points with any MS where gas is odourised in transmission network of the TSO.

(a)Increased transparency and TSO cooperation1111




Yes all gas transmission system follow the same odourisation approach.

Regarding clarification in emails  (29 March) this question is for TSOs


Yes. System operators shall conclude uniform interconnection point agreements for all interconnection points. OBA is the preferred option. Provisions are contained in the Natural Gas Act 2011 and in the Gas Market Model (Amendment) Ordinance 2013.

Note: the English versions of the Natural Gas Act and the Gas Market Model (Amendment) Ordinance 2013 are non-binding documents. For a legally binding version of the texts, please refer to the relevant Bundesgesetzblatt (Federal Law Gazette).


Natural Gas Act 2011 Chapter 3 - Common Provisions - Interconnection Point Agreements

Section 67. (1) The system operators shall conclude uniform interconnection point agreements with each other for all interconnection points between their systems. Such interconnection point agreements at interconnection points shall be concluded in consultation with and following the specifications of the market area manager and the distribution area manager, as applicable. The same shall apply for interconnection point agreements with system operators in other countries and the operators of storage or production facilities. Inasmuch as such agreements with system operators in other countries or operators of storage or production facilities impact on distribution network control, the corresponding contracts shall be concluded following the specifications of the distribution area manager.
(2) Interconnection point agreements shall regulate, in line with the aims of this Act, the technical terms for the interconnection of the systems. Interconnection point agreements shall include the following arrangements as a minimum:
1. technical specifications for the operation of the interconnection point and the systems interconnected at such point, including, but not limited to, gas pressure and quality;
2. a list of the data necessary for the technical control of the interconnection point;
3. data and information exchange procedures;
4. procedures for handling any deviations, in particular in the case of compressor station breakdowns, metering inaccuracies and differences between nominated and allocated gas quantities;
5. procedures and conditions for the mutual provision of linepack pursuant to para. 3.
The interconnection point agreements shall be notified to the regulatory authority. The regulatory authority may request by official decision that the interconnection point agreements be amended where they do not conform to the provisions of this Act.
(3) Each transmission system operator shall establish operational balancing accounts at the interconnection points for the adjoining transmission system operators and the downstream distribution system operators, to enable the use of each others’ linepack. Such operational balancing accounts shall be as large as is technically possible and economically feasible. The limits of the operational balancing accounts at an interconnection point may differ for different systems.
(4) In cases of interconnection points at which schedules or nominations must be submitted, the contracts shall be designed so that system users can normally rely on them being exercised precisely.
Section 26(3) Gas Market Model (Amendment) Ordinance 2013 – Balancing and clearing by the Market Area Manager
(3) Discrepancies between nominated and metered values shall be offset among the network operators by way of operational balancing agreements. At entry/exit points where no operational balancing agreements are in place yet, such discrepancies shall be borne by the system operators. The balance responsible party shall assume that confirmed nominated volumes correspond to allocated volumes.
Interconnection Point Agreements and Linepack Section 29
The interconnection point agreements to be concluded in accordance with section 67 Gaswirtschaftsgesetz (Natural Gas Act) 2011 shall ensure the efficient deployment of linepack as control energy. 

There is no barrier identified or expected currently.

The Gas Market Model (Amendment) Ordinance 2013 contains a provision on gas quality in its Annex 2 (2):

2. Gas Quality
The quality requirements for injecting and transporting gas that are set in the General Terms and Conditions for the Distribution Network shall comply with OVGW regulation G 31 Gasbeschaffenheit (Gas quality) or G B220 Regenerative Gase – Biogase (Renewable gas – biogas) in the version applicable at any one time.

(Please note the due to a revision process of the OVGW regulations, the numbering might have changed). OVGW: Austrian Association for Gas and Water.
(a)Increased transparency and TSO cooperation1111

No. There is no odorisation at transmission level.

No. E-Control is not aware of any research about “masking effects” at national level.

Yes, no odorisation at transmission level.

Units are not fixed in national law/regulation but in technical standards, e.g. in OVGW guidelines G 31 Gasqualität (gas quality), G 177 Gasabrechung (billing). (OVGW: Austrian Association for Gas and Water).


The Luxemburgish law stipulates that the system operators may exchange with foreign system operators to ensure the interoperability of the gas network, and more particularly with system operators from neighbour Member States (art 13). In addition, in order to ensure the security of supply, the system operators have to manage the gas flows taking into account the exchanges with other interconnected networks (art 14.2).
Regarding contractual relations between system operators, the law is mainly focused on the interface between transport & distribution. In this framework, a contract between a system operator and its uphill system operator has to contain the following aspects (art 31) :
·         General conditions to use the network
·         Counting, recording of the load curve and/or application of standard profiles
·         Supplying points to be linked to supplier perimeter
·         Invoicing conditions, payment conditions
·         Exchange and use of data
·         Responsibility aspects
·         Guaranties
·         Termination conditions


Luxembourg receives gas from Belgium (H-quality) and from Germany. In both cases, the gas source is not odourised. Gas is odourised at the Belgian and German entry points.
A potential future inversion of flows towards Belgium or Germany could then be an issue.
On the contrary, the gas received from France is odourised.

(a)Increased transparency and TSO cooperation1111

There is no national rule on this subject.

Luxembourg has only one TSO.




We did an extensive study to figure out the best way to adapt to future gas quality changes and the conclusions are as follows (if you want more details feel free to call me):
Off takers need to adapt their gas burners to be able to handle a wider range of gas quality in the future due to the decline in indigenous production and an increase in imports (LNG and Russian gas)
GTS can blend gasses in the network or add nitrogen and the influx of the worst gasses can be temporarily limited.

(a)Increased transparency and TSO cooperation1111

In the national grid codes the following units are used:

Wobbe index MJ/m3(n)
Transport capacity m3(n;35,17)/hour or MJ/hour
m3 (n) normal conditions of gas are T = 273,15 and P = 101,325 kPa
Since the Netherlands use odorisation on the DSO level and is not connected to countries which use odorisation on TSO level no odorisation problems are foreseen, so all questions concerning this topic are not applicable.


No specific national rules/regulations relating to interconnection agreements.

​The issue of gas quality is adressed in the interconnection agreements signed by French TSOs and their counterparts in adjacent countries.  The current flow patterns do not generate specific issues relating to gas quality: the different specifications are managed by the TSOs and do not hamper cross-border flows. 


​No specific measures foreseen.

THT odorised gas coming from Franceis currently accepted by adjacent TSOs in Luxemburg, Spain, Switzerland and Italy but not in Belgium and Germany.
With regards to exports to Belgium, the existing facilities at Taisnières technically enable bidirectional flows up to approximately 300GWh/d. Only virtual backhaul capacities are currently offered at Taisnières H (to BE).

Physical exports of non-odorised gas from France to Belgium will be enabled as of 2015 thanks to the following technical arrangements:

-          Commissioning of the Dunkirk LNG terminal and creation of a new pipeline flowing non-odorised gas between Loon-Plage (Dunkirk LNG terminal) and the Pitgam compressor station;

-          Shift of the odorisation process from the Dunkirk entry point (Franpipe imports from Norway) to Pitgam;

-           Creation of a new pipeline flowing non-odorised gas between Pitgam compressor station and the new IP with Belgium (Veurne);

With regards to exports to Germany, the existing facilities at Obergailbach technically enable physical flows up to approximately 100-150GWh/d. Only virtual backhaul capacities are currently offered at Obergailbach (to DE).
In its Ten-Year Network Development Plan for 2012-2021, GRTgaz refers to the project of “decentralising” the odourisation process to enable physical flows to Germany (at Obergailbach) and enhanced physical flows to Belgium (at Taisnières). First, GRTgaz plans to flow non-odorised on the section of its network linking Dunkirk (entry from the terminal and entry from the Franpipe), Taisnières H and Obergailbach to the compressor stations of Cuvilly and Morelmaison. As a further step, GRTgaz plans to flow non-odourised gas on its entire high-pressure transmission network, which would enable physical flows from the LNG terminals (Montoir and Fos) to Belgium and Germany. Finally, GRTgaz refers to discussions with TIGF and Enagas on the possibility to decentralise the odorisation process on the French and Spanish network, with the view of enabling physical flows from Spain to North-West Europe.

(a)Increased transparency and TSO cooperation1111

​GRTgaz is conducting a study relating to its project of decentralising the odorisation process in France. The detailed results of this study have not been communicated to CRE at this stage. However, the milestones and timeline are described by GRTgaz in its TYNDP (see response to Q5).

Article 11 of the 19 March 2004 Decree (relating to public service obligations in the gas sector) provides that transmission system operators shall take the necessary measures to ensure that gas delivered at all exits to the facilities of non-domestic customers directly connected to the transmission network and at all exits to distribution networks has an odour that is sufficiently characteristic so potential leaks can be detected. This odour has to disappear once gas is burned.
In France, natural gas is currently odorised with THT in a centralized way, i.e at the entry points to the main transmission network and at the exit from storage facilities. This historical practice has economic justifications: less injection points for THT are needed. In addition, it ensures that the odorisation level is homogeneous on the whole network.

​Not applicable.

The administrative authorization to build and operate the pipelines flowing non-odorised gas in the North-East of France as of 2015 was granted on the basis of compensatory measures to be taken by GRTgaz to maintain a consistent level of safety



The conditions for the access to the Italian network are set in the Legislative Decree n. 164/2000 (as integrated by Legislative Decree n. 93/2011) and in the Authority resolution n. 137/02 and they are implemented TSOs network codes. The above-mentioned rules require, inter alia, the cooperation between interconnected TSOs but they don’t specify the content of the interconnection agreements (ref. art 21 of Legislative Decree n. 93/2011).

The Italian transmission network is already receiving gas from different sources (Russia, Algeria, Libya, Nigeria, Qatar, Norway, etc). No problems or barriers due to different limits set in gas quality specifications at IPs have been reported by TSOs or network users. All the necessary activities related to gas compatibility are managed by Interconnected TSOs through technical agreements.
The criteria to be considered by TSOs to determine whether or not a solution is required should the reporting by network users of specific problems related to different limits set in gas quality specifications at each side. In the absence of reporting the introduction of modifications would be unjustified and potentially problematic.

No specific or additional measures are expected to be prepared at the moment because the Italian transmission network is already handling gas with a different quality and the accepted gas quality range is wide. Any modifications will be in line with the evolution of  European legislation and technical standards.

In Italy gas is not odourised at transmission level. At the moment the only IP where Italian gas system receives odourised gas is Passo Gries, at the Italian/Swiss border. It is gas arriving in Italy from France (through Switzerland) by Transitgas network. There aren’t particular limitations to  gas physical or commercial flow other than the available transport capacity.

Provided that it is a matter which in Italy is almost exclusive ministerial responsibility, no cross-border trade problems related to  odourisation have been brought to AEEG attention by network users.

(a)Increased transparency and TSO cooperation1232

Not known. it is a matter which in Italy is almost exclusive ministerial responsibility.

No. We expect that  the diversification of flow patterns is mainly affected by prices at European hubs and commercial factors.

See answer to question 9

In Italy gas is not odourised at transmission level. Odourisation is carried out by DSOs at TSO-DSO interfaces and by TSOs only at the exit points at the service of end users directly connected to the transmission network. No safety or other technical reasons against this odourisation setting have been brought to AEEG attention.

Not by AEEG.

Law 6th December 1971 n.1083 imposes an obligation of odourising gas for household or similar use. This implies the odourisation of gas by DSOs. TSOs are required to odourize gas only at the exit points at the service of end users directly connected to the transmission network (for household or similar use).


Not by AEEG.


For the metering process
Volumes (please specify the reference conditions of temperature and pressure):
cubic meters 15 °C, 1.01325 bar
Energy content (please specify the reference conditions of temperature and pressure)
Joules (and multiples) MJ/m3 at 15 °C (enthalpy), 15°C, 1.01325 bar
Gross Calorific Value (please specify the reference conditions of temperature and pressure):
Mega-joules per cubic metre MJ/m3 at 15 °C (enthalpy), 15°C, 1.01325 bar
Wobbe index (please specify the reference conditions of temperature and pressure ):
Mega-joules per cubic metre MJ/m3 at 15 °C (enthalpy), 15 °C, 1.01325 bar
Degrees Celsius
For transparency publications: Units foreseen by Regulation 715/2009 Chapter 3 of Annex I  - kWh with a combustion reference temperature of 298,15 K for energy content and m3 at 273,15 K and 1,01325 bar for volume
(ref. TSOs network codes).





(a)Increased transparency and TSO cooperation1111
(a)Increased transparency and TSO cooperation1111


The GB national Network Code specifies that a shipper may not deliver or offtake gas at a entry point or exit point on the transmission system unless a Network Entry Agreement / Network Exit Agreement is in force between the operators, containing certain minimum requirements.  The three existing Interconnection Agreements combine these entry and exit requirements to recognise the bi-directional nature of these points. 

There are three IPs on the GB network:

    1. The BBL interconnector which links Bacton in GB with Baglzand in the Netherlands
    2.  The IUK interconnector which links Bacton in GB with Zeebrugge in Belgium
    3. The GasLink interconnector which links Moffat in GB with Gormanston and Loughshinney in the Republic of Ireland.
Ireland and GB have broadly equivalent gas quality specifications due to the fact that Ireland receives the vast majority of its natural gas from GB.  
However, there are differences between the gas quality specification that applies in GB and those that apply in the Netherlands and Belgium.  Notably, the wobbe index range that applies in GB is narrower than that which applies in the Netherlands and Belgium, which means that GB imports through the BBL and IUK interconnectors could potentially be restricted.
In order to assess whether or not a solution is required, it would first be necessary to form a view about the likelihood and frequency of flow restrictions materialising.  This requires an assessment of the actual gas quality that is likely to materialise at the IP in future years – information which would be held by upstream parties and perhaps shippers but not necessarily TSOs.  It would also be necessary to consider the potential consequences of such potential flow restrictions – both in economic and security of supply terms.  Specifically, regarding the former, the risk of higher gas prices in the potentially constrained member state needs to be balanced against the costs of  solutions to mitigate the flow restriction risk.  Regarding the latter, there is a need to consider the extent to which other sources of supply into a TSO network could meet the potential shortfall from the IP. 
If a TSO is to provide a solution,  then the cost recovery arrangements also need to be considered, particularly if new investment is needed.  Specifically, the questions to consider is whether costs should be socialised among all shippers on the potentially constrained network or targeted at those shippers that bring gas onto the network at the IP.  Alternatively, if the investment made by TSOs is for security of supply reasons then it is relevant to sonsider whether the costs should be partially or fully be spread across consumers.    
In Ofgem's view it is for NRAs (not governments) to approve the arrangements associated with any investment to manage gas quality differences at a cross-border point.
(N.B. CREG have consulted on the possible use of a Peak Shaving facility for use as a gas ballasting facility on the UK-GB boder in order to provide some potential for gas quality adjustment.  It is not yet clear how the costs of this investment can/will be allocated.)


There is currently no formal framework in GB that has been established to manage this potential barrier to gas flows.  Between 2004 and 2007, the UK Government conducted an initiative to investigate the case for GB widening its gas quality specification, which concluded that the specification would not be changed, at least until 2020.  In parallel, GB regulator Ofgem led an industry initiative which examined the potential regulatory arrangements under which NGT might offer blending / processing services at its Bacton entry point (as an alternative to changing the specification) although this did not ultimately become a reality. 


On the Belgian side of the IUK interconnector, we are aware that Fluxys are constructing a nitrogen ballasting facility at Zeebrugge which, subject to the limitations of the facility, could be used to reduce the wobbe index of Belgian gas if necessary in order to facilitate transportation to the GB market.  

All gas tendered for delivery onto NGT’s transmission system must comply with the legal limitations enshrined in the UK law – the Gas Safety (Management) Regulations 1996 (GS(M)R).  However, NGT recognises that new sources of gas may need to be accommodated on its network in future years and has worked with the relevant parties to facilitate such gas being brought into compliance with GS(M)R. 

Not applicable.  ​

The above statement is relevant for the interconnection point at Moffat between the GB and Ireland transmission networks.


                                                               i.            gas can only physically flow from GB to Ireland.  Gas can commercially flow from Ireland to GB.

                                                             ii.            gas can commercially flow from Ireland to GB provided that shippers’ aggregate nominations in the direction of GB to Ireland are greater than shippers aggregate nominations in the direction of Ireland to GB.

                                                            iii.            Maximum contractual volumes are approximately 40 million cubic metres per day, though in reality flows are usually less than half this number.

The existence of different odourisation regimes for gas transmission in GB and Ireland does not present a barrier to physical flows between the two networks.  This is because a barrier only arises where there is physical capability to transport odourised gas to a non-odourised network, not the other way around.  Irrespective of the different approaches to odourisation, there is no physical capability for Ireland to send gas to GB because Ireland is an importer of gas not an exporter.

(a)Increased transparency and TSO cooperation11610

The GB national transmission system made the transition from being odourised to non-odourised in the mid 1990s.  This meant that odourant would no longer be added to the gas at points of entry to the transmission system, but instead would be added at offtakes from the transmission system that fed gas into distribution networks.  This remains current NGT practice.

The main reason for doing this was to facilitate interoperability with the Belgian network due to the construction of the IUK pipeline which started operation in 1997, particularly because the expectation at the time was that gas would flow predominantly from GB to Belgium.
The capital cost of installing an odourant injection facility at each of the 126 offtake points was £21m (at 1998 prices) which was considerably cheaper than the alternative option of installing a deodourisation facility at a suitable location on the GB network.  There would also have been higher ongoing operational costs associated with the deodourisation facility option, partly because such a facility would have generated a waste product that would need to have been managed.
Prior to the decision being taken to move to a non-odourised regime, all end consumers that were directly connected to the transmission system were consulted.  Some of these consumers stated that their safety procedures required odourised gas and in these cases odourant injection facilities were installed close to the point of offtake.  Others were happy to receive non-odourised gas and actually benefitted from the change because it helped them reduce their emissions.
Safety implications of making the change were also considered.  It was concluded that a non-odourised transmission system would be no less safe that an odourised one for the following reasons:
·        It is much less likely that a leak will occur on a transmission pipeline compared to a distribution pipeline due to the different materials used for thier construction;
·        If a leak were to occur, there is a lower risk of explosion on transmission pipelines (which run across the countryside) than on distribution pipelines (which enter buildings)
·        Monitoring pressure (and any drop in pressure) and discolouration of vegetation are more effective ways to detect a leak on a transmission pipeline than a human nose.   

After the new odourant injection facilities had been constructed, implementation of the transition was managed over a period of approximately three weeks during which odourant injection was gradually reduced at the transmission system entry points and gradually increased at the distribution offtakes.  This was done to ensure that the distribution networks did not become over-odourised (which could have caused an increase in the number of public reported gas escapes) taking account of the time required for the gas to travel from the transmission entry points to the distribution offtakes.      


In respect of the GB IPs, GB and Ireland have different odourisation practices. However, this could only potentially hamper the diversification of flow patterns if the Irish interconnector were to be developed such that it could physically flow gas from Ireland to GB.  At present there are no plans to do this because Ireland is a net importer of gas.    

NGT considers that deodourised gas can be considered as an alternative for non-odourised gas (if cost-efficient) in order to address interoperability between networks.  When considering the odourisation-related interoperability issue between Belgium and GB in the 1990s, the installation of a deodourisation facility at a suitable point on the GB network was one of the options considered, however it was not pursued because it was cheaper to change to a completely non-odourised transmission network.  

see answer to question 21. ​

None. ​

The relevant GB legislation governing safety requirements – the Gas (Safety Management) Regulations 1996 – specifically exempts high pressure pipelines from an odourisation requirement:

“The gas shall have been treated with a suitable stenching agent to ensure that it has a distinctive and characteristic odour which shall remain distinctive and characteristic when the gas is mixed with gas which has not been so treated, except that this paragraph shall not apply where the gas is at a pressure of above 7 barg.”
In the light of the above, National Grid makes the following statement in its Ten Year Statement publication concerning odour of gas delivered to the network:
“Gas delivered shall have no odour that might contravene the statutory obligation not to transmit or distribute any gas at a pressure below 7 barg which does not possess a distinctive and characteristic odour”.


None. ​

In GB the transmission system is owned and operated by NGT. Our interconnectors are also all TSOs. Namely, IUK (GB-Bel), BBL(GB-NL), SNIP(GB-NI) and IC1/IC1 (GB-ROI)


Gas Safety (Management) Regulations 1996 GS(M)R


hydrogen sulphide content
 ≤5 mg/m3;
total sulphur content (including H2S)
 ≤50 mg/m3;
Wobbe Number
 ≤51.41 MJ/m3, and ≥47.20 MJ/m3
The Gas (Calculation of Thermal Energy) Regulations 1996


This piece of GB national legislation makes repeated reference to gas temperature of 15°C when defining how gas flow calculations should be completed.


There are no national rules or regulations setting out or governing cooperation between TSOs. CER has oversight and unofficially signs off on the Connected Systems Agreement governing the agreements between adjacent TSOs on interconnectors.


Ireland’s gas quality (GQ) standards are generally in line with the UK’s and as the specifications are aligned, GQ is not seen as a likely barrier to trade. While new sources of gas are expected to come on stream in the next decade (indigenous production at Corrib and LNG imports) these new sources of gas will be required to meet entry specifications.


Also, as physical reverse flow is not available from the Irish to UK market, any differences in GQ specifications will not pose a barrier to trade. In reality however, in the event that physical reverse flow becomes feasible as a result of a surplus of gas in the Irish market after domestic demand is met, it will be necessary to ensure that GQ specifications do not impede trade flows.


TSOs should only be obliged to harmonise GQ where physical reverse flow is possible. ​ 

As Ireland and UK have matching gas quality specifications, no gas quality barrier to trade exists. There is good cooperation between the Irish and UK TSOs, and respective NRAs and there are existing fora where any issues arising could be addressed.


We do not expect gas of a different quality to ‘pop up’ in our network in the next 10 years. Any changes in gas quality are unlikely as Ireland enjoys a relatively protected position from gas quality variations – at the end of a single pipeline with limited indigenous sources. The Corrib gas field is expected to come on stream in 2015 and LNG injection may begin by 2017 at Shannon but both gas sources will be obliged to meet the entry specifications.


The addition of biomethane into the system could also potentially have an impact on GQ in parts of the system but any initial GQ leeway provided to biomethane plants is based on an assumed low level of injection. Any allowance for commingling of biomethane in the natural gas grid would be restricted if high levels of biomethane injection were reached.


The TSO has systematic gas quality monitoring in place which will detect any sudden changes in gas specification but no specific activities are ongoing to prepare for systemic changes in gas quality across the system in future.​ 

This is currently not an issue as we cannot export gas. If in the future Ireland has excess gas after domestic demand is met and can potentially export surplus gas to the UK, we will need to consider the issue of odourisation at transmission level.


Not applicable.​

There are no barriers as there is no surplus of gas in Ireland.​ Ireland has limited indigenous production (approximately 5% of demand) and one storage facility which can provide approximately 10% of demand. 

(a)Increased transparency and TSO cooperation1324

The CER has not undertaken a comprehensive study of a change in odourisation practice specifically. The TSO, in a Regulation 994 physical reverse flow market test for the Moffat Interconnector estimated a deodourisation facility to treat gas flows from Ireland to UK would require a CAPEX of approximately €50m. There would also be on-going costs for such a facility.




 The CER has not studied acceptable levels of odourant.  ​

The odourisation of the transmission network is in line with the ALARP (as low as is reasonably practicable) safety principle upon which all gas safety issues are judged, as required in national legislation. In a geographically small state such as Ireland it is a cost effective way of meeting the ALARP requirement and ensuring public safety from gas leaks. Any change to Ireland’s odourisation practices would require a robust analysis showing clear benefits outweighing the reduction in public safety provided by an odourised transmission system.


Not applicable to Ireland. This question is of more relevance to countries with a number of sources of gas from jurisdictions with diverse odourisation practices, where  the interaction of odourants  results in unintended “masking” of odour.

There is no legislative basis for Ireland’s odourisation practices. Gaslink is required to monitor gas quality, including odourant level under the Code of Operations. The Code of Operations has a legislative basis under Section 13.1 of the Gas Amendment Act, 2002. The CER has a responsibility for gas safety matters, legislated for under Section 9F of the 1999 Electricty Regulation Act, as Amended​

Not applicable.​

See question 13.


Not applicable.

No categories of units are specified under national law or regulation. Gas quality specifications are set out in the Gaslink Code of Operations. The Code of Operations is legislated for in Section 13.1 of the Gas Amendment Act, 2002. The units and ranges set out in the Code are included below.  


Quality Specification Of Natural Gas At Entry Points


Total Sulphur ≤ 50mg/m3 (including H2S)

Oxygen ≤ 0.2 mol%

Carbon Dioxide ≤ 2.5 mol% [1]

Hydrogen Sulphide ≤ 5mg/m3

Water Content ≤ 50mg/m3

Gross Calorific Value (Real Gross Dry) 36.9 - 42.3 MJ/m3

Wobbe Index (Real Gross Dry) 47.2 – 51.41 MJ/m3

Incomplete Combustion Factor < 0.48

Delivery Temperature 1 0C to 38 oC

Hydrogen < 0.1 mol%

Soot Index < 0.60

Organo Halides < 1.5 mg/m3

Radioactivity < 5 Becquerels/g

Ethane < 12 mol %

Nitrogen ≤ 5 mol %

Hydrocarbon Dewpoint ≤ - 2oC up to 85 barg

[1] The CO2 limit of 2.5% will not be considered breached if the total inerts (including CO2) in the gas is less than 8% where: “inerts” in natural gas means carbon dioxide(CO2), nitrogen(N2), helium(He), argon(Ar), and oxygen(O2).​