Editorial: Avoid blackouts by building batteries

The green doors at Roque e Filho—an all-purpose bakery, café, and grocery store and the center of the sleepy southern Portuguese village of Vale da Telha—never seem to close. But late in the morning of Monday, April 28, they were padlocked shut. The screen of the cash dispenser outside was blank.

This scenario was repeated across Portugal as almost every business and household experienced an electricity blackout. Trains above and below ground came to a halt. Elevators stopped between floors. Within 2 h, cell phone signals were out. It was the same in much of Andorra, Spain, and—briefly—southwest France. In all, more than 55 million people were affected, making it the largest blackout ever in western Europe. Power did not return to some parts of Portugal for more than 12 h.

The cause remains unclear. What is known is that electricity grids that rely on large amounts of renewable energy, like solar and wind, must be very robust because the supply of that energy fluctuates more than supplies from nuclear or fossil fuel sources. Without this stability, known as system inertia, grids can go down.

Portugal and Spain are heavily reliant on renewable energy. In 2023, 61% of Portugal’s power came from renewables. The figure was about 50% for Spain, and the two countries have installed more capacity since.

While renewable energy is central to slowing climate change, it comes with challenges. As with many global challenges, chemistry—and specifically chemical energy storage—could be key to solving the problems.

Reports in the Spanish media say that Sara Aagesen, Spain’s environment minister and a chemical engineer, rejects the notion that the stability of the electricity grid was compromised by the drive for renewables.

But some energy grid experts, including Alex Schoch, director of flexibility and electrification at the UK’s Octopus Energy, say a lack of system inertia linked to renewable energy was the problem. “70% of Spain’s power came from renewables, lacking the inertia traditionally provided by fossil fuel plants,” Schoch says in a posting on LinkedIn. “Spain's grid failure began with a loss of generation, triggering instability. The system couldn’t stabilize quickly enough.”

Portugal and Spain have limited battery storage capacity with which to maintain system inertia. “No rapid response: Scarce batteries and demand response meant reliance on slower-acting gas plants, hydro, and imports,” Schoch writes.

The Australian government’s response to a major blackout in southern Australia in 2016 was to purchase a 150 MW lithium-ion battery known as the Tesla Big Battery. During outages, the battery is able to respond in 0.14 sec, as opposed to minutes for traditional generators. South Australia has not had a blackout since, despite a renewable energy share higher than that of Portugal or Spain, Schoch says.

If the Iberian blackout was caused by a lack of system inertia, the installation of lithium-ion or flow batteries could prevent a repeat of the problem, as both are able to rapidly supply electricity during an outage. Flow batteries, which use tanks of charged electrolyte to provide electricity, are highly scalable and well suited to ensuring electric grid stability, producers say. Makers will be hoping that the blackout in Portugal and Spain kick-starts their plans to become major stationary energy providers in the region.

Portugal and Spain already have plans to produce green hydrogen from renewable energy. The hydrogen is intended as a fuel and chemical feedstock, but the countries could ensure that some of it is also available to be quickly fed into fuel cells and converted back into electricity to stabilize the grid if needed.

“A healthy reserve of clean hydrogen storage offers flexibility and resilience to Europe’s energy system,” Jorgo Chatzimarkakis, CEO of Hydrogen Europe, a trade group, says in an email.

It’s Thursday, and the smell of freshly baked bread is once again wafting through the doors of Roque e Filo. But until Portugal and Spain can identify the cause of the blackout and put a solution in place—possibly chemical energy storage—the village store, along with thousands of other businesses across the Iberian Peninsula, may face more blackouts.

This editorial is the result of collective deliberation in C&EN. For this editorial, the lead contributor is Alex Scott.

Views expressed are not necessarily those of ACS.