Kashish - What is "Islanding" in Power Systems?
I was reading up on the Spanish blackout for TDB. I took up this story because ever since I decided to pick up the Green Energy Transition as a topic for my series "The Long Game", I’ve been fascinated by how energy systems work.
So yeah, it was going to be my story. And I thought, since I’ve already done a deeeeeeeep dive into this topic for my series, I couldn’t possibly be caught off guard. There’s nothing I wouldn’t already know about power systems. After all, I thought I knew it all. But the world humbles you in mysterious ways.
I ended up learning a ton of new things—like power inertia, black starts, and a bunch of other fancy terms more related to the physics of electricity systems. One concept I wanted to talk about today is “Islanding” in power systems.
What is Islanding?
Islanding, as the name suggests, refers to a situation where a part of the grid becomes electrically isolated from the main power grid but continues to operate independently—usually with the help of local generation. This means it produces its own electricity and manages its own grid stability, all on its own.
India currently operates under a "One Nation, One Grid" infrastructure. This means that the entire country is interconnected when it comes to electricity. So, in a loose sense, a solar farm in Gujarat can power a house in Assam or meet a sudden spike in demand in the Northeast without much hassle.
One Nation, One Grid
But this doesn’t include India’s islands—the Andaman & Nicobar Islands and Lakshadweep. These islands, in the truest sense, work in isolation, running on diesel generators. Now, this isn’t technically “islanding”. They’re not parts of a grid that became isolated; rather, they’ve never been connected to the national grid. Still, I thought it was worth mentioning.
Coming back to islanding—it can be either intentional or unintentional.
Types of Islanding
Unintentional Islanding
This happens accidentally when a part of the grid gets cut off (e.g., due to a fault or a line break), but local sources—like rooftop solar panels or backup generators—keep feeding power to that section.Intentional (Planned) Islanding
This is done deliberately, often for resilience—think military bases, hospitals, or other critical infrastructure. Microgrids are a good example of this: they can run independently (off-grid) but also connect to the main grid when needed.
Islanding: A Double-Edged Sword
Islanding can be both good and bad.
Let’s start with the good. Islanding can protect the broader grid—by isolating the fault to one section, it prevents short circuits or disturbances in one part of the system from pulling down the entire grid.
That’s exactly what happened in Spain. Spain is part of CESA—short for the Continental Europe Synchronous Area. This is the largest interconnected power grid in the world, operating at a synchronized frequency of 50 Hz. It serves over 400 million people across 24 countries and is operated by the European Network of Transmission System Operators for Electricity (ENTSO-E)—an association of 42 electricity transmission system operators (TSOs) from 35 European countries.
Spain was connected to the rest of Europe through France. When things started going wrong in Spain, it could have pulled down the entire EU power system. And it did impact Portugal and parts of France. But in the nick of time, France’s electric system disconnected its ties with Spain, isolating it to prevent a continent-wide collapse.
Spain experienced islanding—it got cut off. And in this case, it was a good thing.
BUT—
When things began to stabilise and Spain needed help rebooting, it couldn’t immediately take support from the EU grid. It had to come back up on its own, in isolation. So, islanding helped prevent a larger disaster—but also made the recovery slower and harder.
Prerana - Foxholes Grow Forests Better Than Saplings
Today I learned that sometimes, the best way to grow a forest isn't to plant trees—it's to dig a hole.
Yes, seriously.
There’s a clever method of forest regeneration called a foxhole. It's not what it sounds like—there are no actual foxes involved. A foxhole is just a small pit dug into the ground, usually about 10m wide, and a little deep so that if the area catches fire, the hole is safe. What you do next is where the magic happens: you fill this little hole with native seeds, organic matter like compost or leaves, and sometimes even a bit of water-holding soil. Then you wait.
These seeds sprout and grow into plants and eventually trees—but here's the cool part: they often grow better than saplings planted by hand.
Why?
Because saplings grown in nurseries or greenhouses are, well, pampered. They grow up in perfect conditions: regular water, controlled sunlight, no pests, no stress. So when they’re suddenly planted out in the wild—where the sun is harsh, the soil might be poor, and rain is unpredictable—they struggle. It’s like raising a kid in a five-star hotel and then dropping them off in the middle of the desert with no map. They just don’t know how to handle it.
But seeds? Seeds are tough. When you plant them directly in the ground—in their home environment—they adapt from the start. These seeds are primed to survive because, from the very beginning, they have to compete for sunlight, water, and nutrients—just like in the wild. They know how to deal with the heat, the bugs, the tough soil. They grow roots deep into the earth, not shallow like nursery plants that are used to daily watering. And because you're using local, native seeds, you're not trying to force something foreign into the ecosystem. You're just helping nature do what it already wants to do. It's also far far cheaper than the alternative methods.
This method of using foxholes is part of a broader type of regeneration called nucleation or assisted natural regeneration.
Plants in Foxhole Forests grow in mostly three stages:
Stage 1: Pioneer Species These are the first plants to sprout—fast-growing, tough species like native grasses, shrubs, and legumes. They’re built for survival in harsh conditions and help stabilize the soil, reduce erosion, and even improve fertility by fixing nitrogen.
Stage 2: Secondary Species As the soil becomes richer and more stable, slower-growing but longer-living plants begin to take hold. These include small trees and larger shrubs that need more nutrients and shade tolerance than pioneers. They benefit from the groundwork laid by the pioneers and start building a more complex plant community.
Stage 3: Climax Species Eventually, the area supports tall, mature trees—these are the climax species. They’re typically native hardwoods and fruiting trees that form a canopy, support wildlife, and complete the regeneration process. These species represent a stable, self-sustaining ecosystem, much like a natural forest.
I also came across something similar being done in Africa, in a massive effort called the Great Green Wall project. The goal? To stop desertification by restoring degraded land across the Sahel region, just south of the Sahara Desert. One technique they’re using is digging half-moon pits—shallow, crescent-shaped holes that catch rainwater and prevent it from running off. Farmers fill them with compost and plant seeds in them, and the results are stunning. Once-barren land is turning green again.
Both foxholes and half-moons show us something simple but powerful: sometimes the best way to restore the planet isn’t high-tech or expensive. It’s about working with nature, not against it. A little hole in the ground can become the start of a forest, a farm, or even a future.
That's it for today. If you liked this, give us a shout by tagging us on Twitter.