ENEL GREEN POWER
Repowering to improve the use of water resources

Hydropower with the development of solar and wind power in view of the energy transition is now taking on an even more important role: it helps maintain the stability and security of the power grid. Wind and solar are in fact two intermittent technologies that depend on the presence of wind and sunshine. Hydropower in this context can guarantee the stability of the system. In addition to the modulation and regulation capability of reservoir systems, it is in fact possible, thanks tohydroelectric pumped storage facilities, to rapidly produce large amounts of clean energy from water stored in an upstream reservoir, at times of highest demand.

It is therefore essential to maintain and improve plant performance, especially through so-called repowering.

What is repowering?

The repowering ofhydroelectric power plants consists of replacing and modernizing some or all of its major components. These could be, for example, the generators or turbines (the number of which can be increased), components for machinery automation, or even hydraulic systems, i.e., systems that use liquids to move or regulate mechanical power. The goal of repowering is to bring about an increase in the installed capacity and/or output of an existing plant. Another important part of repowering is the general modernization of the plant and the extension of the useful life of its machinery.

With repowering we give new life toplants, thereby feeding new energy into the grid that would otherwise be lost. And that is precisely why we have been investing in the refurbishment of our power plants for a number of years. In Italy, for example, we have prepared a plan with a budget of about 40 million euros for interventions on pumped storage plants that will be completed by the end of this year, while repowering interventions on conventional plants are underway with an additional investment. We are continuing to invest in local areas and plants, some of which were built more than a century ago, at a time when hydropower played a key role in industrialization.

Improving water resource use and environmental impact

Many of our repowering investments are designed to improve water use, thus avoiding waste especially in agricultural areas. Improvements are also being made in the reservoirs of hydropower plants, by allowing the amount of water that is released to be regulated more precisely. Furthermore, planned water releases from dams can improve the production potential of crops.

Our interventions enable plants to be increasingly sustainable and integrated, and this improves their environmental footprint. We are building passage ramps, genuine fish ladders that encourage the repopulation of waterways upstream of the plants. We are also installing turbines and valves that do not need oil, thereby avoiding possible sources of pollution.

Our ongoing Repowering and Refurbishment campaign in Italy includes interventions in about 20 plants with a total installed capacity of about 4,500 MW (the plants in question include Quarto, Ponte Malon, Castelletto, Ca' Barzizza, Sillico, Cassino, Vinchiana, Vaccarizzo, Entracque, and Roncovalgrande). The Crego power plant in Piedmont is an excellent example of our goal: here Repowering has led to an increase in production of more than 28 GWh per year. We have initiated a similar program in Spain: at the Flix Power Station on the Ebro River we have managed to increase production by 10 GWh per year.

Capodacqua, a power plant that's also a symbol

The Capodacqua hydroelectric plant in Italy's Marche region has twice been destroyed and rebuilt: the first time was in 1947, shortly after World War II, and the second time was earlier this year, following the earthquake that struck central Italy in 2016. This is a small power plant, whose energy serves the equivalent of 800 households, and in the coming months and years it will primarily power the many reconstruction sites. Plants like this, with a history that goes back more than 100 years, are an integral part of the local area and community, with which, for us, dialogue is essential. Together, the renovation work that led to the reopening of the plant represents the future: in fact, we used green building techniques, employing wooden structures (which respond better to seismic stress) and insulation with rice straw (rice husk). Very special attention was also paid to reuse, to circularity. This circularity is also symbolic because the tiles will be made from scraps from the rubble of buildings that were destroyed by the earthquake, in the same way that certified rubble scraps were used to fill the holes that were dug.