Europe needs to invest €67bn a year in its electricity grid until 2050 to stop further outages such as the one that blacked out Spain and Portugal last week, according to industry association Eurelectric.

“Investing in a resilient grid is no longer optional,” said a Eurelectric statement. “The success of Europe’s energy transitions depends on an extended, fully digitalised grid that can manage the amount of renewables capacity that is set to come. Making the grid fit for the purpose requires an annual investment of €67bn from now until 2050.”

However, it said existing technologies could help reduce these costs. By optimising grid use, annual investment needs could drop to €55bn without compromising resilience or performance.

“The blackout was a wake-up call,” it said. “It showed that the need to modernise and reinforce Europe’s electricity grid is urgent and unavoidable. Now is the time to invest in the infrastructure that powers everything.”

On Monday last week, Spain’s transmission system was disconnected from the European grid at the 400kV level due to an issue with a power line connecting French and Spanish Catalonia. The fault triggered a domino disrupting electricity supply not only in Spain but also in Portugal, Andorra and parts of France.

Spain’s transmission system operator, Red Eléctrica (www.ree.es), restored 99% of the electricity supply by early Tuesday morning, but investigations into the root cause of the blackout are still ongoing.

“What we do know is that we had a very serious incident, one that has had major impacts in several European countries at the same time, something that is very, very rare” Eurelectric’s secretary general Kristian Ruby told the BBC (www.bbc.co.uk/sounds/play/m002bhkp).

While the cause of the blackout is yet to be defined, there were reports of anomalous oscillations in the high-voltage lines before the power shut down. These oscillations caused synchronisation failures between the electrical systems and eventually ended in disturbances across the interconnected European network.

The blackout disrupted key infrastructure across Spain and Portugal, affecting public transportation, traffic signals, hospitals, manufacturing plants, digital payment systems and nuclear power facilities. Banking systems were interrupted, auto traffic control systems went dark, metros were stopped and intercity trains were halted. Hospitals were particularly affected, with many having to activate on-site generators and reduce services while power was restored.

The statement (www.eurelectric.org/news/what-you-need-to-know-about-the-iberian-peninsulas-blackout) described the “extraordinary event” as “a stark reminder that the grid is the backbone of our society. With electricity playing an increasingly important role in our society, we need to create all the conditions for enable a secure electricity supply.”

Ruby added: “As society relies more and more on electricity, it’s crucial that electricity is reliable.”