Tâmega: one of the largest hydroelectric projects developed in Europe in the last 25 years

Iberdrola adds two wind farms to the Tâmega hydroelectric complex, one of Europe's largest energy storage facilities that is located in Northern Portugal, making it one of the country's most significant energy initiatives ever. The giga-battery, which involves the investment of more than 1.5 billion euros, will entail the construction of three dams and three power plants (Gouvães, Daivões y Alto Tâmega) with an overall capacity of 1,158 MW. The wind farms will have a capacity of 300 MW.

Tâmega River (north of Portugal)

Total installed capacity
1,158 MW

Energy production
1,766 GWh per year

Project investment
More than 1,5 billion euros

Start date
Between 2021 and 2024

Investment in the Sociocultural
and Environmental Action Plan
50 million euros

Job creation
13,500 direct and indirect jobs

Tâmega giga battery

The hydroelectric Tâmega project involves the construction of three new power plants: Gouvães, Daivões and Alto Tâmega, which will be erected over the Tâmega River, a tributary of the Duero in the north of Portugal, close to Oporto. The three power plants will have an installed capacity totalling 1,158 MW, representing an increase of 6 % in the total installed electrical power in the country.

The complex will be capable of producing 1,766 GWh per year, enough to meet the energy needs of the neighbouring towns and the cities of Braga and Guimarães (440,000 homes). Furthermore, this large renewable infrastructure will have sufficient storage capacity to serve two million Portuguese households for an entire day.

Tâmega will mean the end of 1.2 million tonnes of CO2 emissions annually and will diversify the generation sources, doing away with imports of over 160,000 tonnes of oil per year. It will also promote to the economic activity and the employment in the region, since it is estimated that during the entire construction phase 3,500 direct jobs and 10,000 indirect jobs will be generated — 20 % of them from neighbouring towns — through more than 100 providers — 75 of them from Portugal. Several hundred people will be hired in operational phase.

The project, which will involve an investment of more than 1.5 billion euros, including funding from the European Investment Bank (EIB). In July 2018, this financial institution loaned Iberdrola 500 million euros, the first tranche of the 650 approved in total for the funding of this development.

The project also includes, in its Environmental Impact Statement (EIS), a number of ecological system compensation measures, such as the reforestation of over 1,000 hectares, the planting of 17,000 cork oaks, and actions to improve the populations of protected fauna found in the area.

Gouvães and Daivões will start operating in 2021 and Alto Tâmega will be operational in 2024.


In addition, two wind farms will be built and linked to the giga-battery, converting the complex into a hybrid power plant, whose eventual power is expected to reach 300 MW, making this one of Portugal's biggest wind projects.

They will also become the first plants of this type connected to a grid to be erected in the area around the three power plants (Gouvães, Daivões and Alto Tâmega) that will make up the Támega complex.

Generating electricity from two sources — hydroelectric and wind — will make it possible to consume energy in periods of high wind and improve efficiency by feeding the dam pumping system, recovering water for upstream reservoirs.

The company will be able to manage supply and demand between the hydroelectric and wind plants depending on the availability of each resource, but also on the price dynamics in the energy market.


The construction of the three new dams and hydroelectric power stations, including a pumping station, is continuing at a good pace and is now two-thirds complete, in line with the timetable established.

In March 2021, the first filling of the Daivões reservoir was concluded. Its associated power station will have a capacity of 118 MW thanks to the installation of three generator sets. This marks the culmination of a masterpiece of design and execution with a concrete "arch-gravity" dam 77.5 m high and 265 m along the crown, using 240,000 m3 of concrete. The body of water it creates has a surface area of 340 ha and a volume of 56.2 hm3.

The creation of the Daivões reservoir entailed building a 200-metre-long and 35-metre-high bridge, more than 5 km of electric power lines, more than 7 km of roads and two sewage processing plants.

This Daivões dam is the lower reservoir of the 880 MW Gouvães Hydro-Electric Pumped Power Station. When the Gouvães dam — the upper reservoir — is full, the generator turbine tests will be able to start, followed by the pumping system tests.

This power station will be reversible, meaning it will be able to store water from the Daivões reservoir in the Gouvães reservoir, taking advantage of the 650+ metres height difference between the two. This makes it possible to pump energy when there is a surplus in production and recover it when required. Its storage capacity is sufficient to provide a continuous electricity supply for the Oporto metropolitan area for 24 hours.

The Gouvães quarry is operational and producing aggregates for exclusive use in concrete mixes for the Tâmega hydro-electric complex; including those required to build the dams. This quarry is forecast to produce over 2 million tonnes of aggregates, equivalent to the weight of 5,000 fully equipped Boeing 747s carrying passengers.


The chairman of Iberdrola group, Ignacio Galán, and the Portuguese prime minister, António Costa, visited the Tâmega giga battery works in January 2020, one of the largest energy stores in Europe. Galán stressed that "developing infrastructure such as this is only possible if there is clear planning, a stable framework, legal certainty and continuous dialogue to seek solutions to the inevitable incidents that can arise throughout its construction and operation".

The chairman's visit demonstrates the group's commitment to Portugal and its willingness to continue operating in the country. In addition to the Tâmega project, the company has other new renewable developments in Portugal since it has recently been awarded the go ahead for new solar capacity to more than double its operational renewable power in the country. It will, therefore, be able to supply clean energy to more than 800,000 of the company's Portuguese customers with its 1,519 MW of renewable capacity: 1,158 MW of hydroelectric technology, 255 MW photovoltaic, 14 MW battery storage and 92 MW wind energy, the latter of which is already in operation.

Ignacio Galán, chairman of Iberdrola group

We will continue to drive the energy transition in this country and, with it, the creation of wealth and well-being for all Portuguese people


The Tâmega giga battery will provide almost 900 MW of pumping capacity to the Portuguese electricity system, which is an increase of more than 30 % compared to the megawatt capacity available to the country today.

Iberdrola is leader in energy storage with an installed power of 4,500 MW using pumping technology, the current most efficient storage method, since it generates no atmospheric contaminating emissions and its performance is much higher than that of the best storage banks in the market. The company expects to reach 90 million kilowatt hours (kWh) of storage capacity by 2022, which is an increase over 2018 of almost 30 %: 20 million kWh more, equivalent to 400,000 electric car batteries or 1.4 million batteries for residential use.

Hydroelectric power plants like the Tâmega are a safeguard for the electrical system. The largest facility of this kind in Europe is the Cortes-La Muela complex in Valencia.


  • Tâmega Project

    This Plan, developed in the context of the Tâmega project and signed by the different Municipal Chambers participating in it, includes a record figure of over 50 million euros for the economic, social and cultural development of the Alto Tâmega region.

    The purpose of the program is to contribute to the development of the region and improve the standard of living of the population — it's estimated that 3,500 direct and 10,000 indirect jobs will be generated during the execution of the complex — as well as to preserve the environment where the project will be carried out, from an environmental point of view. Planned actions will be carried out in the municipalities of Ribeira de Pena, Vila Pouca de Aguiar, Cabeceiras de Basto, Boticas, Chaves, Valpaços and Montalegre.

    An example is the region of Boticas, in which Iberdrola has participated in the development of the Boticas, Nature and Biodiversity park, building accommodation for visitors and encouraging actions for the compensation of the natural environment's flora and fauna.

    Boticas, Nature and Biodiversity park.

    Boticas, Nature and Biodiversity park.

    The company is going to carry out this type of remedial action for the local flora and fauna both in Boticas and in Cabeceiras de Basto, Ribeira de Pena, Vila Pouca de Aguiar and Chaves by signing two collaboration protocols. The actions planned include the management, recovery and conservation of forest populations of indigenous species, the recovery of riverside forests and improving the connectivity between river courses, planting cork oaks and improving aquatic ecosystems.

    In addition to these projects, Iberdrola is funding other activities, such as the improvement of the public sewer and water supply networks, upgrading and optimising sporting facilities, upgrading the equipment used by fire brigades, new recreational areas, etc. In addition, it has co-funded the construction of the new and flagship facilities and installations in the area, such as the Alvão Village Campsite, the Pedras Salgadas Horse Riding Centre or the Educational Health Resort in Vidago.

    With this type of aid, Iberdrola consolidates its commitment to sustainability and social responsibility.

  • Tresminas Roman gold Mining Site

    Tresminas Mine Complex, Portugal. Video voice transcription (Spanish version) [PDF]

    As part of the construction of the large Tâmega Hydroelectric Complex, Iberdrola has also promoted a visit to the Tresminas Roman gold Mining Site, a project that is part of the compensation actions carried out by the company pursuant to what is established in the Environmental Impact Statement. 

    With the investment of 1.84 million Euros in the Tresminas Mine Complex, Iberdrola is demonstrating its commitment to the economic, social, cultural and environmental development of the communities where it operates. The company is collaborating with the Vila Pouca de Aguiar Town Council and the North Portugal Regional Department of Culture in the historical, archaeological and heritage enhancement of the region. This investment started in 2016 and is expected to continue until 2023.

    The company has allocated, between 2016 and the end of 2018, around 850,000 Euros which, throughout this year, will be invested as follows:

    • The funding of the technical equipment.
    • The continuation of the historical geological and fauna and flora studies in Tresminas.
    • The acquisition of equipment for visits to inverted cone pits and mine-shafts, and for their maintenance and/or clearance.
    • The construction of the support building and structures and equipment to support movement in the inverted cone pits and mine-shafts.


    The Tresminas Roman Mine Complex was, during the Roman Era, one of the main gold explorations in the primary deposits of the conventus bracaraugustanus and one of the most significant ones in the Northwest of the Peninsula: it is estimated that between the I and III centuries A.D. around 25 tonnes of pure gold were obtained from Tresminas, which involved the ejection of millions of tonnes of rock excavating open inverted cone pit mines.

    Iberdrola is committed with this initiative to the preservation of local and national heritage in the region of Tresminas, as well as to make the archaeological and historical importance of this mine complex well known and to boost tourism in the area.

    The investment made by the company allows a set of actions to be carried out that benefit the Tresminas Mine Complex, facilitating its future recognition as an Archaeological Park, which will safeguard the materials associated with Roman mining and the landscaping of the area.

    Tresminas is part of the municipality of Vila Pouca de Aguiar's strategic pillars in terms of cultural tourism.  The efforts made over the last few months, both at local and regional level, following the enhancement of the heritage and tourism value of Tresminas, have already resulted in an increase in the number of visitors to the region.


    In fact, these results have been supported by activities in cross-border partnership with Las Médulas, UNESCO World Heritage Site since 1997 and one of the most important and well-known Roman mines, in the El Bierzo region in Spain. The candidature is made jointly, in a common cultural project, which aims to enhance the value of the Iberian Peninsula's Roman mining legacy. In 2017, this cooperation protocol between the Municipality of Vila Pouca de Aguiar and the Las Médulas Foundation was supported by organisations such as the Direção Regional de Cultura do Norte and the Castilla y León regional government's General Directorate of Cultural Heritage. This alliance aims to further strengthen the candidature of this area of Portugal as a UNESCO World Heritage Site.