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Carlo Esterle: 110-year-old Italian plant combines beauty, history

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Carlo Esterle: 110-year-old Italian plant combines beauty, history
(Veduta esterna della centrale idroelettrica Esterle, illuminata nella notte, a Cornate d'Adda, in Italia, nel Marzo 2013.)

By Edison Spa

The 23 MW Carlo Esterle plant is one of the first hydroelectric power plants built in Italy. It contributed considerably to the country’s industrial development at the beginning of the 20th century, and the facility is renowned for its architectural structure that satisfied the need for status and decorum that a growing company like Edison Spa desired as a means of social self-assertion. Today, the Esterle powerhouse continues to operate reliably, producing more than 180 million kWh of electricity each year.

Carlo Esterle was one of three hydropower plants inducted into the Hydro Hall of Fame in 2023. Lignum Vitae North America was the sponsor for the Hydro Hall of Fame in 2023 at HYDROVISION International. Read on to learn more about the history of hydro development along the Adda River and its contribution to the lives and livelihood of the local residents.

Hydro Hall of Fame

Developing the Adda River

Edison is the oldest energy company in Europe, with more than 135 years of records, and is one of Italy’s leading operators with activities in the procurement, production and sale of power and natural gas and in energy and environmental services. The company’s roots go back to the banks of the Adda River, from where it contributed to shaping the history of Italian and European hydroelectricity.

In the late 19th and early 20th century, Edison revolutionized Italy’s electrification system, including with the construction of the first hydroelectric power plants along the banks of the Adda River. This was a radical innovation for the economic and social systems of the time that made it possible to bring electric light to towns and homes, transform industrial production processes, and lay the foundations for a different organization of life for people and businesses.

Specifically, the Bertini, Esterle and Semenza plants, among the oldest in Italy, are the symbol of a disruptive technological and innovative background, which made it possible to electrify Milan and northern Italy as early as the end of the 19th century. Without hydroelectric power, the industrial development of Lombardy and Italy would not have taken place.

The 11 MW Bertini plant in Paderno, which came into operation in 1898, holds the record as Italy’s oldest hydroelectric plant and has been in operation for 123 years. At the time, it was one of the most powerful hydro projects in the world, second only to the one on the Niagara River in the U.S. Bertini is the brainchild of Giuseppe Colombo, the rector of the Polytechnic and founder of Società Generale Italiana di Elettricità Sistema Edison in Milan in 1884. He recognized water as a renewable, safe, reliable and competitive source of energy, unlike coal, which had to be imported to Italy and was three times more expensive than that sold in England. For Milan, the construction of the first hydroelectric plant on the Adda River meant a new role as an industrial city, boasting an efficient electric traction transport system by the end of the century that placed it at the forefront in Europe, and found a solution to the shortage of energy sources.

The plant was built in an area of Italy most affected by industrial growth and progress in the technological and scientific fields. Right along the Adda River there were a cotton mill and a workers’ village, today a World Heritage Site. Electric lighting was introduced in this factory in 1882 thanks to an Edison generator driven by the river’s waters.

To carry the energy generated from the Adda River to Milan, a 32-km-long power line was built, carrying 9,500 kW, a power never before transmitted, and special ceramic insulators were designed for the transmission lines. This was an unprecedented feat, which made sustainable electricity available to the city. It also extended the use of electricity, which until then was limited mainly to lighting some areas of the historic centre of Milan — such as Piazza del Duomo, some large stores and the Teatro alla Scala — and assisted the transformation of the means of production of companies and factories, which replaced steam engines with more efficient ones with electric motors, powered by a safe and reliable source of energy. Furthermore, it was possible to electrify Milan’s tram network, replacing horses, for fully sustainable public mobility.

With the growing demand for electricity, driven by the region’s industrial development, a new, more powerful hydro plant was built along the Adda River. It was built on the right bank of the river in the municipality of Cornate d’Adda (Monza-Brianza area), where an old farmhouse once stood, about 500 m downstream from the Bertini plant. The construction work began in 1910, under the direction of engineer Alberto Mussato, and was completed four years later. The plant went into operation on May 15, 1914, and was dedicated to Carlo Esterle, Edison’s managing director from 1897 to 1918.

This first group of hydroelectric power plants launched a revolution that accelerated and transformed Italy’s industry and society. And the Esterle plant has operated continuously since that time.

Six turbine-generator sets were installed in the plant, each consisting of a 5,150 kW turbine and a 6,600 kVA 42-period alternator. Two of these sets were also equipped with a second 5,850 kVA 15.8-period alternator for service to the Italian railways (managed by Ferrovie dello Stato). Indeed, in view of the construction of the plant, Edison had signed a contract with Ferrovie dello Stato to supply 6,000 kW power for the electrification of the Milan-Lecco line.

The Esterle hydro plant is known for its architectural beauty. With its exquisite embellishments, intricate geometric and floral motifs, columns and capitals at the entrance, wrought-iron lampposts and drainpipes, and Gothic-inspired glass windows, it looks more like a villa than like an industrial building. The structure, with a rectangular floor plan and a two-pitch metal truss roof, is characterized by two other notable features on its sides: one oriented toward the river is the main entrance to the plant, and the other oriented toward the hill is the penstock arrival chamber. Inside, the walls and ceilings of the engine room were intricately decorated, as are the mosaic floors, lampposts, lamps and numerous wrought-iron furnishings. 

The hydropower plant has been refurbished and revamped a few times since 1998. Consequently, it can be considered a modern plant in terms of technology, reliability and performance. However, these interventions have always safeguarded the integrity of the original structure, not only of the building but also of the machinery, to the point they are hardly noticeable. Specifically, although a new control room was set up, carefully concealed from view, the historic and valuable equipment has been preserved.

A few years after the inauguration of this plant, in 1917, Edison began the construction a third hydroelectric plant in Calusco d’Adda, dedicated to Guido Semenza, one of the plant’s designers. This 7 MW plant became operative on August 16, 1920, following the path traced by the electricity companies, which showed a desire for monumental buildings, whose style largely reflected the architectural taste of the time. The combination of beauty, art and engineering has always characterised the banks of the Adda River. Edison’s commitment to environmental protection is confirmed by the constant attention paid to landscape preservation and its impact on the territory. The power plants are fully integrated in their surroundings and landscape and preserve the natural ecological integrity of the Adda River.

A history of reliable service

Edison still owns these three hydroelectric plants. They produce more than 260 GWh each year, have a total installed capacity of 41 MW, and are able to meet the energy needs of more than 100,000 households and avoid the emission of 73,000 tonnes of CO2 into the atmosphere. In addition, these plants are open to the public on certain days of the year.

Editor’s Note: The 2024 Hydro Hall of Fame inductees will be announced during the opening keynote session at HYDROVISION International in Denver, Colo., U.S. Click here to learn more and register.