The tunnel of nearly 400 metres (1300 ft) length will feed the Daivões power station.

As per the Spanish electric utility company, work will commence on the inner concrete reinforcement lining and also the cofferdams. This work it said, will help in diverting the Tâmega river, a requisite to begin the construction of the dam and the Daivões power plant.

The dam, which will be of a height of 77.5 metres (255 ft), will serve the Daivões power station by feeding two turbines of a combined capacity of 114MW and a production of 142GWh.

An additional 4MW turbine will also be installed to increase the power station’s output by another 17GWh.

Three large dams Gouvães, Tâmega and Daivões will feature in the Tâmega complex. The associated electricity generating units altogether will have an installed capacity of 1,158 MW and a combined annual production capacity of 1,760GWh.

The Tamega project is being undertaken in northern Portugal, near Porto with an investment of more than €1.5bn.

About 3,500 direct and 10,000 indirect jobs are expected to be created during the construction phase of the energy project.

As of now, Iberdrola has about 54 people making up its project management and works supervision team with the number expected to move up to 165 once the most intense phases of the project commence.

Iberdrola said that additionally an operation and maintenance team will be created later on for each of the power stations which will likely be manned by employees recruited from the locals.

Once completed, the Tamega river complex is expected to have a pumped storage capacity that is equivalent to 300,000 homes, said the company.

Image: Iberdrola Daivoes hydroelectric plant. Photo: courtesy of Iberdrola, S.A.