Today, electricity is generated using different technologies and primary energy sources (coal, natural gas, fuel oil, diesel, water, wind, sun, biomass and waste). The number of generators in mainland Portugal has increased significantly as, in addition to the old, large thermoelectric and hydroelectric power stations, there are now many others with lower power using co-generation or generation from renewable sources.
REN - Redes Energéticas Nacionais operates the National Transmission Grid (RNT), which connects generators to consumption centres and ensures a balance between energy supply and demand. It is the only electricity transmission entity in Portugal under a concession agreement with the Portuguese state.
The RNT delivery points feed the distribution network that supplies most final consumers.
Electricity supply companies are responsible for managing relations with end consumers, including billing and customer service.
Electricity is distributed in the National Distribution Network, which consists of high, medium and low voltage infrastructures. The low-voltage distribution grids are operated under concession contracts between municipalities and distributors.
The organised electricity markets operate freely and are subject to authorisation from the Portuguese state. Ordinary status generators, suppliers and special status generators can become market agents if they wish to do so.
Suppliers can buy and sell electricity freely and are entitled to access the transmission and distribution grids on payment of access tariffs fixed by the regulator, ERSE. They are subject to public service obligations with regard to quality and a continuous electricity supply and must give their customers access to simple, understandable information.
The consumers are the reason behind this complex system. There are almost 6.2 million consumers in mainland Portugal, most of them using low voltage, 23,500 medium voltage and 350 high and extra high voltage.
They used more than 49 billion kWh in 2013. After the opening of the electricity market in Portugal, consumers who wish to do so are free to choose their electricity supplier.