REN operates the National Natural Gas Transport Network (RNTGN), which carries the natural gas from entry points in the high-pressure pipeline to the exit points that supply the distribution networks and users with direct high-pressure connections. It is the sole natural gas transport concession holder in Portugal and covers the entire mainland.
Storage takes two forms: underground storage of gas in gaseous form and LNG storage. Underground storage abides by a public service concession contract between REN and the Portuguese state, which covers injection, storage, extraction, treatment and delivery of gas to the high-pressure network. It also includes the construction, operation, maintenance and expansion of related facilities and infrastructures. LNG storage is handled by REN Atlântico, which is also responsible for reception and regasification of LNG and then delivery to the high-pressure network.
Under the existing concessions, REN handles the planning, construction and operation of all the system's infrastructures (transport, storage and regasification).
Under current legislation, REN - Redes Energéticas Nacionais is responsible for conducting 10-year planning studies of the National Natural Gas Transport Network in order to coordinate network development plans with national demand forecasts. These studies must be sent to the competent authorities for prior approval, without which it is not possible to go on to the investment phase.
It is also REN's legal obligation to collaborate in official studies of medium and long-term security of the country's de natural gas supply.
Investment in the natural gas transport network has kept up with the growth in the country's consumption. The expansion of the Sines Liquefied Natural Gas Terminal, which was completed in July 2012, was particularly important. It increased useful storage capacity of LNG by 62.5%, to 390,000 m3, raised gas emission capacity to the network by 50% to 1,350,000 m3/h, adapted the jetty for reception of high-capacity tankers and implemented a number of procedural reinforcements to maximise the availability of infrastructure and a high standard of operational safety. As a result, the Sines Terminal now offers favourable access conditions to more agents and more flexible management of imported volumes. It boasts unique conditions for the reception of LNG ships from more remote, diversified sources, thereby contributing to the sector's competitiveness in Portugal and security of supply to the SNGN.
The development of underground gas storage capacity in Carriço is currently under way, with the construction of new caverns at depths of between 1,000 and 1,300 m with an average usable capacity per cavern of around 50 million normal cubic metres. This facility is essential for setting up the security reserves necessary to guarantee the country's supply in the event of a supply crisis and also offers conditions for logistical and commercial optimisation of commercial agents in the sector in Portugal and Spain.
The latest developments in the high-pressure transport network focused on the connection of new delivery points and the remodelling of some pressure reduction and metering stations in order to adapt them to the new operating conditions and gas flows. A compression station with a total power of 12 MW will soon be built in the Carregado area. It will increase the network's transport capacity and also make its operation more flexible in order to respond to capacity requests from consumption points.
The RNTGN consists of main and branch pipelines totalling 1,248 kilometres and 195 pipeline stations (84 sectioning valve stations, 66 intermediate junction stations, 84 pressure regulation and metering stations and two custody transfer stations).
Its layout includes a main pipeline running through the west of the country between Sines and Valença do Minho, where the main natural gas consumption points are located, a transit pipeline interconnecting the central zone of the system in the Leiria - Pombal area with the eastern border with Spain, two lots that supply the interior of the country in Beira Interior and several branches, including the one that supplies the Lisbon and a connection to the Carriço underground storage facility.
The entry points in the network include the connection of the Sines LNG Terminal, two fully reversible interconnections with the Spanish high-pressure natural gas network in Campo Maior and Valença do Minho, through which the natural gas from North Africa reaches Portugal, and also the connection point to the Carriço underground storage facility. Historically, imports of gas into Portugal can be divided into 55% LNG unloaded in Sines and the other 45% reaching the country via the Iberian pipeline network.
As the overall technical system manager, REN Gasodutos is responsible for access to infrastructures by third parties, for ensuring a balance between supply and demand and efficient management of the high-pressure natural gas network.
The overall technical management of the system coordinates the operation of the RNTGN and distribution networks connected to the system, thereby guaranteeing security of supply, freedom of access and equal treatment of all agents, in accordance with criteria of non-discrimination, impartiality and transparency.
REN Gasodutos is responsible for managing the interconnection of the RNTGN with international networks and underground storage infrastructures and the LNG terminal and controlling the formation and maintenance of safety natural gas reserves.