Who is the power grid killer?

On April 28, 2025, at 1:03 PM local time, long lines of locals rushed to buy tissues and bottled water in front of a supermarket in Spain. Pedestrians anxiously held up their phones, unable to make a call or send a message.

Half an hour earlier, Spain experienced a massive power outage. Within five seconds, the country lost 60% of its electricity, prompting the Ministry of the Interior to declare a state of emergency.

This "century-long blackout," lasting until the early hours of the following day, also affected parts of Portugal and France. The extent and duration of the outage were "extremely rare," impacting the lives of over 50 million people.

Ironically, just on April 16th of that year, Spain announced it had achieved its first-ever "100% Renewable Energy" power supply, with all its electricity for the day supplied by wind, solar, and hydroelectric power.

What exactly happened on the Iberian Peninsula?

According to the ICS Expert Investigation Team Fact Report on the Grid Incident in Spain and Portugal on April 28, 2025, we can understand that: On the morning of April 28, everything was normal; after sunrise, the share of renewable energy generation steadily increased.

At 12:03, the Spanish power grid began to experience frequency oscillations. Simultaneously, due to cloud cover, the output of many small Rooftop Solar Panels plummeted, or perhaps due to increased actual demand on the grid, resulting in a power shortage of 525MW.

To suppress grid oscillations, the power output exported from Spain to France began to decrease repeatedly, but this unexpectedly pushed up the system voltage.

Half an hour later, the power grid was like a fully drawn bow:

At 12:32:57, affected by the continuously rising voltage, a transformer in Granada that supplies power to multiple solar, solar thermal, and wind Power Plants tripped due to overvoltage protection, further increasing the grid voltage.

12:33:16, Badajoz unit disconnected from the grid.

12:33:17, Segovia unit disconnected from the grid, followed by Huelva, Cáceres…

Finally, at 12:33:19, the Iberian power grid completely lost synchronization with the European continent amidst violent fluctuations.

Clearly, this was not a natural disaster.

Renewable energy accounts for 66.2% of the Spanish power grid, with wind and solar power each accounting for approximately 25%. However, hydropower, solar thermal, gas-fired, coal-fired, and energy storage units with regulation capabilities only account for about 43.2% of the total.

When wind and solar renewable energy become the mainstay of the grid, will their inherent intermittency and volatility make the grid more vulnerable?

Can we build a system that not only "generates electricity" but also actively "stabilizes" the grid?

But before that, let's look at another question: Why hasn't China, as the country with the largest amount of renewable energy generation and the largest scale of renewable energy grid connection in the world, experienced a nationwide or even province-wide blackout for a very, very long time?

The answer is that it hasn't been a very, very long time.

Because now, any power shortage can be immediately replenished from provinces with abundant power.

It's important to understand that at the beginning of the People's Republic of China, the total installed power generation capacity was only 1.85 million kilowatts, with an annual power generation of 4.3 billion kilowatt-hours, equivalent to the annual electricity consumption of a medium-sized city today; the per capita electricity consumption of 8 kilowatt-hours was equivalent to the power consumption of a modern household air conditioner for only a few hours, and over 80% of the population lacked access to electricity.

However, 76 years later, China's power grid has developed into the world's largest AC/DC interconnected grid, forming a grid interconnection pattern of "west-to-east power transmission and north-to-south power supply."

Today, my country boasts the world's highest transmission voltage level and the longest ultra-high-voltage transmission lines, with its power grid's safety and reliability ranking among the world's best.

However, even such a "powerful" power grid is showing some "headaches" under the increasing impact of the growing scale of new energy grid integration in recent years.

By the third quarter of 2025, the installed capacity of new energy sources in my country had reached 46%. With large-scale grid connection, the power generation time of traditional energy sources has been severely squeezed.

This has led to a gradual decline in my country's grid regulation capacity.

In traditional thermal power plants, when the grid frequency drops, the massive rotational inertia of the generator's large rotor releases kinetic energy, slowing the speed decrease, effectively adding a buffer to the grid.

The boilers and steam pipes in thermal power plants are natural heat storage carriers, serving as an energy source for grid regulation.

So, how can this squeezed regulation capacity be compensated for?

Initially, the idea was to increase energy storage system, storing electricity during peak grid periods and discharging it during off-peak periods, acting as a buffer like a reservoir to ensure stable grid operation.

However, such energy storage has limitations: it must be connected to the grid to operate stably, and its operating voltage and frequency follow the grid it's connected to. If faced with the same problem as Spain, it will also fail and disconnect from the grid. This is what we commonly call grid-connected energy storage.

In contrast, there is grid-based energy storage. Compared to a reservoir, this is more like an independent water pipe.

It doesn't rely on an external power grid, can autonomously set its voltage and frequency, and can operate independently even if the external power grid fails. Furthermore, it can act as a black start power source after a grid failure, supporting grid recovery. From January to September 2025, grid-based energy storage accounted for 10% of newly added energy storage during the same period.

Currently, approximately 7.4 billion people worldwide rely on a stable power grid, but at the same time, about 700 million people live without electricity, awaiting grid coverage.

With advancements in new energy power generation technologies and declining costs, these regions will undoubtedly integrate more new energy power in the future, using new technologies like grid-based energy storage to prevent a repeat of the Spanish power grid tragedy and illuminate every corner of the earth.

Perhaps this is the significance of our pursuit of green energy.