The Eel-Friendly Dam
It’s more than 90 years old but looks great for its age. It’s part of Sardinia’s history and is still a reference point for the inhabitants of the island – the Coghinas hydroelectric plant.
Talking about a power plant as if it were a person is not out of place if we are speaking about Coghinas. The plant, for nearly a century, has been part of the daily lives of those living at the foot of the mountain Ruiu, and a familiar presence, fully integrated in the environment around the riu – as they say in the Sassari dialect – from which the plant takes its name, one of the island’s most important rivers.
It was in 1926 that the Coghinas dam first let out the waters of its artificial lake to generate electricity. In the same year, London was celebrating the installation of its first automatic traffic lights, in the United States, the Disney character of Mickey Mouse was introduced for the first time, and the world was grappling with turmoil and totalitarianism that would go on to mark the lives of entire generations to come.
This endeavour, built in one of the areas with the most rivers in Sardinia, was the pride and joy of the engineering of the time and stood out for two distinct features that would last throughout the following decades: operational efficiency and protection of the environment and biodiversity.
"The artificial lake can contain 240 million cubic metres of water: a reservoir that is essential not only for bringing electricity to the northern region of Sardinia but also for permitting the irrigation of fields and crops in the area."
The three horizontal-axis generators that ran until 1991 allowed for the illumination of houses and buildings at full efficiency. After more than sixty years of loyal service, they gave way to one single vertical-axis Francis turbine, which has the same level of performance: it has worked for two decades with an average of 4,000 hours a year, without requiring any special maintenance.
Thanks to an overall review of the plant, done in 2016 by the Business Hydro Sardinia Unit of Enel, and the support of the units of Operation and Maintenance Hydro, the Coghinas hydroelectric group at the Muzzone dam will now be able to stay in service for another 20 years.
Biodiversity at the Forefront
The plant is able to produce 70,000 MW a year for a basin of 25,000 households with the reduction rate of carbon dioxide emissions of about 45,000 kilograms.
Our focus on the environment is a distinctive trait of the plant. The 1,740 square kilometres of its catchment area have strategic value, also in terms of agriculture and tourism: every year, the dam, 58 metres tall with a 158-metre long crown, provides 80/90 million cubic metres of water, protecting fish populations at the same time.
"In 2015, the Coghinas plant opened a ladder system to facilitate the reproduction of eels, allowing them to move continuously between the artificial lake and the river bed."
This project, for the protection of biodiversity, involves the Coghinas plant as well as the one downstream, Casteldoria, helping to enhance the entire river where the two dams stand.
Financed and prepared by the Province of Olbia-Tempio, the project involved collaboration with the towns of the area, with the common goal of continuing our shared commitment of protecting the environment of this evocative corner of Sardinia, full of history.