Spain seeks to turn reservoirs into 'batteries' for surplus energy storage

Barcelona: Spain's leading energy companies are considering turning reservoirs of water into "super batteries" to store surplus energy produced by renewables.

The Ministry for Ecological Transition said it had received 40 requests to carry out preliminary investigations into the feasibility of reversible hydropower plants that can store and generate electricity. Among the applicants are major energy companies including Iberdrola, Endesa, and Repsol.

Pumped storage hydropower, in which water is transferred between two reservoirs at different elevations to generate power as it passes through turbines, is a system that aims to utilize Spain's surplus energy from solar and wind power, an energy expert from the University of Barcelona told Xinhua news agency on Wednesday.

This solution would be one of the most immediate methods to store energy from renewable sources, whose production is intermittent, according to Cristian Fabrega, coordinator of the Master in Renewable Energies and Energy Sustainability at the University of Barcelona.

The professor noted that the concept of pumped storage hydropower is not new and has been used in other parts of the world for decades. Given Spain's current situation, this system can help manage the country's growing energy surplus "until we come up with other alternative technologies for storing energy."

If all renewable sources of energy generation were taken into account, the total share of renewables in Spain's energy mix in June amounted to 58.7 percent. If nuclear power was included, clean technologies accounted for 80 percent of Spain's energy mix.

Spain already has 21 pumped-storage hydroelectric plants with a combined capacity of 5,380 MW. Another 40 such plants could add 15,000 MW of storage capacity, but the expert warns that completing so many projects will not be easy.

"It's a good idea as it's an available technology, but the problem is that it's not simple," Fabrega said, citing a major problem such as whether the location has proper geography and necessary water resources, and if building dams and new reservoirs has a big environmental impact.

The large rise in renewable energy in Spain has prioritized energy storage, leading the government to update its Integrated National Energy and Climate Plan (INECP) to simplify the administrative process of building new reversible power plants.

The European Union approved the INECP update in January. The plan will run until 2030 and sets the ambitious objective of renewable energy providing 81 percent of the electrical power in Spain.

"The electrical grid involves amounts of energy that are hard to imagine, and the storage method currently winning, as it were, the race to find suitable technology seems to be the alternative of green hydrogen, which is why it's being pushed so much at the European level," added Fabrega.

Green hydrogen is obtained through the chemical process known as electrolysis, in which an electrical current separates hydrogen from oxygen in water, producing a fuel source without emitting carbon dioxide into the atmosphere.

To "avoid putting all its eggs in one basket," the expert suggests the Spanish authorities develop a range of energy storage solutions, instead of favoring energy diversification.