The National Natural Gas System (ESFA) is the Natural Gas System (high pressure) which includes the following:[1]

The central pipeline and its branches and the planned expansions and upgrades of the System, the metering, regulation, compression and decompression facilities, the operation control system, communications and remote control, the operation and maintenance centers, the load distribution control centers and the facilities which constitute the elements of the operation and support of the Transportation System, as well as the existing entry points of the metering station of Sidirokastro, Nea Mesimvria, Agia Triada Megaron Attica and Evros Kipi.

The LNG Installation on the island of Revythoussa.

The projects of expansion and enhancement of the System, the facilities, interconnections and infrastructures for storage and re-introduction of Natural Gas to the System, carried out in accordance with the approved Development Program, as stipulated in the Operation Code. The projects included in the Development Program are projects of public benefit and of major national importance.

Natural gas enters the country from 4 entrances, from Bulgaria, at the Sidirokastro entrance, from Turkey, at the Kipi entrance, from the Liquefied Natural Gas (LNG) Terminal of Revythoussa, in the area of ​​Megara, where it is unloaded from ships and gasified and is introduced into the Transmission System at the entrance of Agia Triada, while since December 2020 the flow of natural gas from the TAP pipeline, at the entrance of Nea Mesimvria, began.

Operator of the National Natural Gas System.

The operator of the National Natural Gas System is the company DESFA S.A., which was established in 2007.[2] The shareholders of DESFA,[3] are 34% the Hellenic State and 66% SENFLUGA HOLDING COMPANY ENERGY INFRASTRUCTURE S.A., which is a joint venture of the companies “Snam S.p.A.” (Transmission System Operator of Italy), “Enagás Internacional S.L.U.” (Transmission System Operator of Spain), “Fluxys S.A.” (Transmission System Operator of Belgium) and “DAMCO S.A.” as a passive shareholder. DESFA has been certified as a “Separated Ownership Natural Gas Transmission System Operator” (i.e., according to the Ownership Unbundling model of Directive 2009/73/EC) by RAE Decision No. 1220/2018, as revised by No. 460/2019 Decision of the Authority.

DESFA must operate, maintain, exploit and develop the System and the interconnections included in it, in order to be cost-effective, technically safe and integrated, so that the needs of the Natural Gas Users are served, in a safe, sufficient manner , reliable and cost-effective and to ensure the operation of a single natural gas market in the European Union and the protection of the environment.