Battery energy storage systems (BESS) have become a solution to prevent surpluses from being lost and to cover the intermittence of renewable energy. “We need energy storage solutions to make them permanent,” says researcher and electric battery expert Philippe Knauth in an interview for bbva.com. He also points out that the democratization of energy depends on “the combination of renewable energies and energy storage.”
According to the latest data from the International Renewable Energy Agency (IRENA), At the end of 2023, global renewable energy capacity amounted to 3,870 gigawatts (GW), an increase of 13.9 percent. Of this figure, solar energy accounted for the largest share of the world total, with a capacity of 1,419 GW.
As renewable energy keeps growing, Knauth sees storage as the only way to deal with a simple fact: wind and solar power do not flow steadily. “Sustainable energy sources are clearly intermittent. Solar panels produce nothing at night, and wind turbines stand still when the air is calm. To make these sources reliable, we must store the power they generate,” he says. That is why he insists a sustainable future cannot exist without energy storage. In Spain, he says, “solar power is a sound choice... when paired with energy storage.”
Moreover, battery energy storage systems (BESS) could help democratize access to electricity. “In remote areas, such as in the mountains or in poorer countries, coupling renewable power with storage is a must for bringing energy to more people,” Knauth says.
The challenges of renewable energy storage
Yet energy storage systems have their hurdles. “They do not last long enough. Some materials, like cobalt, are toxic; others are scarce. Most must be mined, which adds to carbon emissions,” he says.
Today, lithium batteries are the most common. Their key strength is their high energy density, both by weight and by volume. But “they pose safety risks, as they use flammable organic solvents. Their lifespan is short, and lithium itself is fairly scarce,” he warns. Worse, if a battery overheats, “the vapor pressure of organic solvents in the electrolyte inside rises. Should the casing crack under that strain, the hot solvent vapor can leak out, mix with air, and ignite.” To tackle these issues, “nanomaterials may help, but the real breakthrough would be solid electrolytes, which would do away with volatile, flammable liquid solvents,” Knauth says.
As for alternatives to lithium, sodium batteries already exist. But, he notes, “sodium is four times heavier than lithium, which lowers energy density.” That means less energy stored.
Still, among existing electrochemical batteries—sodium, magnesium, vanadium redox, and zinc iodide—sodium will certainly take the lead, he says. “Magnesium still faces big hurdles. Vanadium redox batteries work only for large-scale storage, as they rely on liquid tanks, making them unfit for portable devices. Zinc iodide falls short too, as it lacks enough energy and is too heavy.”
From an environmental perspective, the expert stresses the need to avoid toxic materials like cobalt in lithium-ion batteries. “The materials should be abundant, not scarce or critical,” he says. “A long lifespan and the ability to recycle are also vital. All these factors must be weighed together.”
The role of 'cleantech' in the development of energy storage systems
Clean technologies are crucial in both mitigating and adapting to climate change, and energy storage systems are a key part of this ‘cleantech’ revolution. “Sustainable and clean solutions undoubtedly offer major benefits,” Knauth says. However, he predicts that “in the future, people will demand even more from these technologies.” As a result, energy storage will remain “a major market in the years ahead.”