Only Market Agents who are registered at the Directorate-General of Energy and Geology (DGEG) as suppliers are permitted access to transmission networks, as set out in Decree-Law No. 231/2012 of 26th October 2012, which republished Decree-Law No. 140/2006 of 26th July 2006, and which defines the legal systems for the operation of the National Natural Gas System (SNGN).
It is the responsibility of the Energy Services Regulator (ERSE) to oversee the rules, procedures and the technical and commercial conditions for accessing SNGN networks, infrastructures and interconnections, particularly with regard to establishing mechanisms for governing the use of the National Transmission Network, Storage Infrastructures and LNG Terminals (RNTIAT). This ranges from the setting by Operators of the abovementioned infrastructures of the maximum technical capacities, available capacities for the market, mechanisms for allocating capacity and the mechanisms for managing congestion in the RNTIAT.
These rules are defined in the following documentation published by ERSE:
Access to Networks, Infrastructures and Interconnections Code of the Natural Gas Sector
Procedures Manual for Access to Natural Gas Sector Infrastructures
Procedures Manual for the Overall Technical Management of the Natural Gas Sector
Access Portal to the Natural Gas Infrastructures