Inertia

In the culturally rich and diverse Iberian Peninsula, an unprecedented blackout swept across mainland Portugal and peninsular Spain on April 28, plunging millions into darkness for over 10 hours, with some areas enduring power outages that lasted up to 16 hours. It disrupted telecommunications, transportation systems, emergency services, and daily life across the peninsula.

The incident reignited discussions on transitioning responsibly to renewable energy sources especially since Portugal and Spain pursue some of Europe’s more ambitious green energy targets.

Spain’s grid operator, Red Eléctrica, attributed the failure to insufficient voltage regulation from major power plants, while energy companies like Iberdrola and Endesa pointed to outdated grid systems and lack of interconnection as contributing factors.

The Iberian blackout brought the vulnerabilities of rapidly transitioning to renewable energy into sharp focus and put forward the critical issue on infrastructure resiliency and readiness.

I recently had the chance to see a presentation by Meralco first vice president and head of networks Engr. Froilan Savet on this topic to understand how the Iberian blackout can serve as a cautionary tale for the Philippines given our interest in increasing the share of renewable energy in our power supply mix.

Engr. Savet enlightened this columnist on the issue, explaining that the Iberian blackout was a problem on inertia. The high integration of variable renewable energy sources into the grid resulted in a low inertia system which made the Iberian Peninsula more vulnerable to power swings and system imbalances.

Simply put, the 2025 Iberian blackout wasn’t a failure of renewable energy. It was a stability problem.

Traditionally, coal, gas, and nuclear plants have provided baseload power due to their stability. Renewables however are intermittent by nature.

Until large-scale storage becomes widespread, relying too heavily on renewables without diversification and adequate infrastructure could result in instability.

The lesson here is clear: for all its merits, renewable energy is not yet a reliable baseload power source and its integration into the power supply mix should go hand in hand with investment in grid modernization and flexible power generation to ensure that the experience of  Spain and Portugal  will not be repeated.

A  grid that is already stretched by aging infrastructure and vulnerable from powerful typhoons needs more baseload capacity in the system.

Injecting variable renewables without these firm capacities in place may result to dire consequences.

This, however, does not mean that the green agenda should be abandoned altogether. Rather, it is a reminder for the country to pursue renewables wisely and strategically.

The key is balance. The pursuit of sustainability must not come at the cost of energy stability and security. A truly sustainable energy future must be built on resilience- where clean generation is matched by strong and smart systems that can deliver and stabilize power reliably.

The Philippine Energy Plan aims to increase the share of renewable energy in our power generation mix to 35 percent by 2030, with a further expansion to 50 percent by 2040.

As we scale to more variable renewable energy sources, let’s not just add renewables. Let’s make sure that our grid is ready – technically, operationally and locally.

The country must also address issues such as grid modernization, energy storage, and the integration of balancing power sources.

Distribution utilities must lead not just in the delivery of electricity service but in ensuring resilience as well.

The Philippines has made huge strides in the pursuit of a more sustainable energy future but we must not be too complacent. The Iberian blackout was a wake-up call. It revealed a critical gap between policy and technical preparedness. This gap, if left unaddressed, could erode public trust in the energy transition. The lesson here is clear: a green grid must also be a strong grid.

We must adopt a holistic approach that prioritizes the green agenda along with energy security and stability.

After all, a truly sustainable energy future can only be achieved if there is reliable, stable, and equitable energy for all Filipinos.