Iberdrola's recent activity in the Tagus basin has transformed the Torrejón-Valdecañas axis into a hydraulic gigabattery capable of storing large volumes of energyThanks to a series of technological improvements at the Valdecañas pumping station, the system multiplies its capacity to absorb renewable surpluses and release them when the grid needs them most.
This project, located in Cáceres, relies on the connection between the reservoirs of Alcántara and Valdecañas, two of the largest water reserves in EuropeThis consolidates the Tagus River as one of Spain's strategic energy storage hubs. Without requiring any major new civil engineering works, the facility has already successfully completed its first pumping cycles.
A gigabattery on the Tagus River: added power and capacity
With the modernization of the Valdecañas power plant, Iberdrola has increased the available power of 355 megawatts (MW) and storage of 210 gigawatt hours (GWh) additional capacity in the Tagus system. This expansion reinforces the stability of the electricity supply and facilitates integration of more wind and solar energy.
The extra 210 GWh of storage capacity translates into very concrete figures: it is equivalent to average annual consumption of approximately 60.000 households, to more than four million electric vehicle batteries charged or to more than two weeks of the total electricity consumption of Extremadura, according to the company's estimates.
In addition to the added pumping power, the new Valdecañas configuration incorporates a hybrid battery with 15 MW of power and 7,5 MWh of capacityThis solution combines large-scale hydroelectric pumping with electrochemical storageproviding greater flexibility and speed of response to changes in demand or renewable generation.
All this reinforcement of the system has been carried out without the need to build new dams or alter reservoir levels. The actions have had a primarily electromechanical scope, renewing equipment and making use of existing infrastructure, including electric transmission lines.
The company frames these investments within its storage strategy, which considers one of the pillars of the energy transition along with renewable generation and smart gridsIn Extremadura, its hydroelectric facilities already total around 2.000 MW of power, to which a greater manageable storage capacity is now added.
How the Torrejón-Valdecañas gigabattery works
The Torrejón-Valdecañas system operates as a large reversible battery Based on water and gravity. When there is abundant renewable production and demand is low —for example, at midday with high solar generation or during windy hours—, the plant uses that surplus electricity to pump water from a reservoir at a lower elevation to one at a higher elevation.
In this case, the key lies in the connection between the reservoirs of Alcántara and Valdecañas, which act as the lower and upper reservoirs of the pumping stationThe energy that might otherwise be wasted is stored in the form of reservoir water, waiting for the right moment to be used.
When the electrical system requires more electricity—for example, during peak consumption hours—water is released from the upper reservoir to the lower one, passing through turbines that They transform the potential energy of water back into electrical energyThe cycle can be repeated continuously, without direct emissions and without the need for fossil fuels.
This operating principle is, in essence, the same as that of A conventional battery: stores energy when there is excess and releases it when needed.The difference is that here the "electrolyte" is water and the system operates on a gigawatt-hour scale, allowing it to provide regulation and backup services to an entire region.
Hydraulic pumping does not generate new energy on its own—in fact, consumes electricity during the pumping phase—, but it allows for much better use of the production from variable renewable technologies such as wind and solar photovoltaics. Thanks to this mechanism, renewable energy curtailment is reduced and grid stability is improved.
Benefits for Extremadura and the Tagus basin
The Torrejón-Valdecañas gigabattery offers advantages that go beyond the electrical system. comprehensive coordination of the Valdecañas, Torrejón, Alcántara and Cedillo reservoirs, together with the control of the Tiétar tributary by pumping, offers a more advanced water management in the Tagus basin.
This coordinated scheme allows to slow down floods and reduce the risk of flooding During periods of heavy rainfall, it allows water to be transferred between reservoirs according to available capacity. It also helps conserve river ecosystems by maintaining more stable flows and levels within established operating limits.
Another relevant aspect is the creation of strategic water reserves for the whole yearBy being able to mobilize water resources between different reservoirs, their availability is optimized both for electricity production and for other uses, in a context of growing concern about water management in the Peninsula.
Extremadura is thus consolidating itself as a key territory for the development of hydraulic pumpingThanks to the existence of large reservoirs and hydraulic systems that can be technologically adapted or expanded, the region already has several projects of this type, with the Tagus River as the main focus.
On a national level, Iberdrola has more than 4.200 MW of installed capacity in pumped hydroelectric power plants, which places it among the main renewable energy storage operators in the countryThe reinforcement of Valdecañas fits into this context of expanding storage to support the massive deployment of clean energy.
Hydraulic pumping in the energy transition
The development of pumped storage plants like Valdecañas has become a key piece of the future of the Spanish electricity systemIn a scenario with high levels of wind and solar power generation, the big challenge is how to store electricity when there is a surplus and recover it when there is a shortage.
In this respect, reversible pumping offers a mature, large-scale solution and free of direct emissions, which converts variable renewable production into manageable energyIt allows balancing the imbalances between generation and demand, reducing the need to resort to backup fossil fuel power plants.
Storage in the Tagus River and other basins is especially relevant for Maintain security of supply and grid stabilityBy having large volumes of stored energy, the system operator can more easily cope with consumption peaks, sudden drops in renewable generation, or grid incidents.
The actions carried out in Valdecañas also stand out for their character of modernization without major additional impactsThey have focused on the renewal and improvement of electromechanical equipment, without building new dams or large auxiliary infrastructures, and taking advantage of existing power lines.
However, the company emphasizes that deploying new large-scale pumping capacity requires long-term water concessions and revenue stabilization mechanisms appropriate. A clear and predictable regulatory framework is considered essential to encourage more similar projects that support the transition from fossil fuels to clean energy sources.
Taken together, the transformation of the Torrejón-Valdecañas axis into a hydroelectric gigabattery illustrates how the combination of large reservoirs, pumping technology and battery storage systems It can strengthen both the integration of renewables and water management. The Tagus River experience places Extremadura on the European map of energy storage and demonstrates the role these infrastructures can play in an increasingly decarbonized electricity system.
