Vinci: How to store electrical energy – PSP

October 22, 2021 – Sustainable development – Morocco

VINCI Construction * is building a pumped storage power plant (PSP) in the Anti-Atlas massif in Morocco, near the Abdelmoumen dam and not far from Agadir. The PSP will allow Morocco to store electrical energy in the form of water when demand is low, and then harness it when demand increases – essentially, by generating renewable energy on demand.

Renewable energies like solar and wind are crucial for the energy transition underway in the countries that signed the Paris Agreement in 2015, all of which aim to achieve carbon neutrality by 2050. Morocco is one countries that have set themselves the most ambitious renewable energies. objectives, aiming to use wind and solar power to supply half of its electricity mix by 2030.

PSPs, an efficient energy storage solution

The problem is that solar and wind are intermittent sources of energy because they are impacted by factors such as light winds or heavy cloud cover, for example. Storing the excess energy generated when conditions are good – for example when the wind blows regularly – is therefore very important, so that the excess can be fed back into the grid when conditions deteriorate, with minimal waste.

Many energy storage solutions exist, but one of the most effective is to use water to adjust electricity supply and demand. In times of overproduction, the energy generated is used to store water in the upper reservoir. When the plant needs to generate more power, water is released and, by gravity, flows through a penstock to the turbine, which also serves as a pump. Here, the pressure rises, producing electricity. This is the turbine process, as opposed to the pumping process, where water is pumped upward. Pumped storage was originally developed in Switzerland at the end of the 19th century.

This mechanism is the principle of PSP, or pumped storage power plants. For large production, a PSP requires two tanks separated by a significant difference in altitude – at least 100 meters. This rise is reflected in the PSP under construction by VINCI Construction 70 km from Agadir in Morocco, which will be crucial for the country to achieve its energy transition objectives.

Abdelmoumen, an ideal site

The Abdelmoumen site was not chosen on a whim; located in a mountainous region, it has sufficient height – 600 m – for the flow of water to develop sufficient power as it passes through the turbines. Meanwhile, the nearby Abdelmoumen dam will supply water to the PSP and compensate for any evaporation. In addition, the dam’s electrical installations will enable the energy generated during periods of low electricity demand to be used to operate the pumps and re-inject it during peak hours.

A huge project on the steep slopes of the Anti-Atlas massif

At the start of the project, the site was almost entirely underdeveloped; the teams therefore started by building 20 km of access roads to the various areas of the site. Helder de Sousa, project manager at VINCI Construction Terrassement, said: “the ground was very hard, but we managed to excavate 5 million cubic meters of earth”.
Abdelmoumen site

The huge project consisted of digging two reservoirs of 1.3 million cubic meters, separated by a slope of 1,400 m and connected by a system of partially buried pipes, with an internal diameter of 5 m, able to withstand a pressure. of more than 60 bars. This pipeline system will supply water to the two power generation turbines, each of which has a capacity of 175 MW. The installation and stowage of this penstock were completed in 2021.

The pumping and turbine plant is located between the two reservoirs, in a trench 60 m long and 50 m wide buried 40 m underground. The teams also built the structure around the pumps and turbines – an 8-story building with 6 underground levels, capable of withstanding the vibrations of the turbines and major earthquakes that frequently occur in the area.

Delivery of all facilities is scheduled for 2022, with commissioning expected shortly thereafter.

* Following an international call for tenders, the Abdelmoumen PSP project was awarded to a consortium led by VINCI Construction Grands Projets and involving the German and Austrian subsidiaries of the electromechanical group Andritz Hydro.

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