Today, all the natural gas used in Portugal comes from third countries. A part is received by high-pressure pipeline and the other by sea (in the form of liquefied natural gas - LNG).
REN Gasodutos operates the National Natural Gas Transport Network (RNTGN), which receives the natural gas at the Spanish border, as it leaves storage facilities (REN Armazenagem) or at the regasification terminal (REN Atlântico) and delivers it to distributors or high-pressure end users. REN Gasodutos holds the concession for the high-pressure transport of natural gas, which includes overall technical management of the National Natural Gas System, through which it coordinates the operation of natural gas distribution and transport infrastructures, which guarantee the continuity and security of supply. It is also responsible for proposing development of the system.
Reception, storage and regasification of LNG and underground storage and transport of natural gas are carried out under 40-year concession contracts with the Portuguese state. More specifically, REN Atlântico holds the concession for the reception, storage and regasification of LNG at the Sines LNG terminal and REN Armazenagem holds a concession for underground natural gas storage in Carriço in the municipality of Pombal.
As in the electricity system, the supply of natural gas and the management of the organised markets are open to competition.
The natural gas markets are operated on an open-market basis and require authorisation from the Portuguese state. The natural gas is sold to end consumers by the suppliers, which buy and sell it freely on the open market or in bilateral contracts.
The consumers are the reason behind this complex system. There are more than 1.3 million consumers in mainland Portugal, most of them low-pressure consumers, 279 medium pressure and 21 high pressure. In 2011 they used more than 57 billion kWh, which corresponds to around 4.7 billion square metres.
After the opening of the natural gas market in Portugal, consumers who wish to do so are free to choose their electricity supplier.
The natural gas is received at the border and transported by high-pressure National Natural Gas Transport Network pipelines connected, through pressure metering and reduction stations, to the medium-pressure pipelines operated by the distribution companies.
At the underground storage facilities in Pombal, the high-pressure natural gas is stored in gaseous form in caverns created inside salt formations at depths of over 1,000 metres.
At the Sines terminal, the gas is received in liquid form (LNG). After being unloaded from the tanker ships, the LNG is sent to intermediate storage tanks where it awaits a regasification order from the owner of the gas. At the end of this process the natural gas (now in gaseous form) is compressed and injected into the high-pressure network at the terminal's delivery point.
Storage in gaseous or liquid form ensures security of supply and flexibility for market agents and consumers.