From The KlimaNachrichten

A Germany-wide power outage is not a light switch problem – but the moment when the physical limits of green energy policy become ruthlessly visible

Who does not remember the promises? The energy transition should not only save the climate but also guarantee security of supply. Wind, sun and batteries – the holy triumvirate of the green future. Decentralized, democratic, digital. What is often concealed is that in the event of a nationwide blackout, this future system will turn into a pile of expensive electronics that do not produce a single volt. Not because the wind doesn’t blow or the sun doesn’t shine – but because the physical foundations are missing to bring the grid back to life in the first place.

The current power outage in Berlin, which paralyzed about 50,000 households for four days, provides a taste of what is in store for Germany when the last conventional power plants are taken off the grid. And no, it’s not about scaremongering – it’s about physics.

The grid is not a power distributor, but a machine

First, let’s look at the technical reality of a blackout. The European power grid runs at a grid frequency of 50 hertz – a precisely synchronized machine in which all generators rotate in unison. After a total collapse, there is: no reference frequency, no voltage, no communication over the network. Everything has to be synchronized from scratch, step by step, like a house of cards that you build in absolute darkness.

This is not a “reboot” as you know it from the computer. It is the laborious reconstruction of a highly complex system, lasting several hours to several days, in which the slightest miscalculation leads to an immediate renewed shutdown.

Black Start: The Underrated Ability

Only a few power plants can start without an external power supply. According to the Federal Network Agency, there are 174 black-start capable turbines with a capacity of at least 10 MW (as of 2020) in Germany – sounds like a lot, but of these, only 26 are actually earmarked by the transmission system operators for grid reconstruction. This is the strategic reserve for an emergency.

The following are primarily:

• Hydroelectric power plants
• Some gas turbines (with battery support)
• Few specially equipped power plants

On the other hand, the following are not eligible for black starts:

• Nuclear power plants (irony of history: long since shut down)
• Most coal-fired power plants (in the process of being shut down)
• Wind and photovoltaic systems (grid-following)
• Large battery storage systems (without upstream supply)

You read that right: The entire infrastructure of the energy transition is useless in the event of a blackout. Not restricted use. Useless.

Why is the reconstruction taking so long?

A large power plant needs between 5 and 10 percent of its nominal output as its own needs to start up – for pumps, lubrication, cooling, control and control technology. Without mains or black start source: standstill. And even when the first power plants are up and running, the real problem begins: the balance between generation and load must be exactly right. Too much burden? Frequency drop, shutdown. Too little load? Frequency surplus, shutdown.

That’s why consumers are being connected gradually: first critical infrastructure, then household’s region-by-region, industrial companies come to the very end. The net is built up like a fragile house of cards – one wrong move, and everything collapses again.

In addition, there are failed protection relays in substations that have to be reset manually. Cables must be tested for short circuits. Communication is now only via emergency power generators. Typical time frames for Germany-wide reconstruction: 24 to 72 hours – under ideal conditions. With consequential damage, much longer.

The problem of renewables: grid-following instead of grid-forming

Now it gets interesting. Almost all of today’s wind and photovoltaic plants are grid-following. They need an existing voltage and frequency to attach themselves to. After a blackout, the following applies: No grid, no feed-in. Even in bright sunshine and strong winds: 0 megawatts.

At this point, the argument regularly comes: “Then let’s just take battery storage as a buffer.” Nice theory. Practical reality: Batteries do not provide physical inertia. They stabilize the frequency only via control algorithms – highly sensitive to load jumps, highly software-dependent. Who sets the first cycle after a total failure? Who synchronizes thousands of inverters so that they do not regulate against each other? A bug, a communication failure, a misparameterization – and the chaos is perfect.

Grid-Forming Inverters: The Theoretical Solution Without Practical Proof

The answer of the energy transition engineers is: “Grid-forming inverters.” These are intended to digitally replicate the lack of network formation of synchronous generators. Sounds good. However, as of today, it only works in theory and in small pilot projects.

The problems:

• Hardly tested on a large scale so far
• No long-term experience for national networks
• Extremely complex protection and coordination issues
• Highly software-dependent

This is not a physical anchor like a rotating flywheel, but a digital replacement model. A software update can stabilize the system – or cause it to crash. Although the European grid codes discuss requirements for grid-forming functionalities, Germany is miles away from a comprehensive, tested implementation.

Fraunhofer ISE and other research institutions are diligently developing algorithms and testing prototypes. But there are worlds between a test setup and a nationwide system change – and years, if not decades.

Dark doldrums plus blackout: The worst-case scenario

Now imagine the following scenario: A cold January day, little wind, no sun, the storage facilities are already partially empty (because they had to support the supply in the days before). Then: blackout.

What happens? No feed-in from wind and solar. No inertia in the system. No safe reconstruction path.

In such a system, Germany would de facto be dependent on neighboring countries – French nuclear power plants, Scandinavian hydropower, Polish coal – to “pull” voltage and frequency into the German grid and enable a new start. Energy sovereignty? Not given. Green independence ends where physics begins.

What politicians conceal

The Federal Network Agency classifies the risk of a long-lasting power outage in Germany as “very unlikely”. This may be statistically correct – Germany has one of the most reliable power grids in the world with an average of 11 minutes of outage per year. But this statistic applies to today’s system of conventional baseload power plants that serve as anchors.

What happens when these anchors disappear? When the last coal-fired power plants are taken off the grid and replaced by software-controlled inverters? Will the grid become more stable – or more vulnerable?

Herbert Saurugg, Austrian blackout expert, has been warning for years: “Just because you can start a power plant illegally does not mean that you can also manage grid reconstruction.” And further: The smaller the turbines, the more difficult and lengthy the start-up.

A 100% RE system would have, in the event of a nationwide blackout:

• No robust black start capability
• No physical mesh formation
• High software and coordination risks
• Extreme dependence on weather and foreign countries
• Significantly longer reconstruction times than today

In extreme cases, the network could no longer be safely started up independently.

Berlin as a portent?

The current power outage in Berlin – caused by a fire at a cable bridge – is an example of how fragile even well-developed urban grids are. It took four days for all 45,000 households to have electricity again. Four days of cold, four days without functioning heaters, without hot water, without light. According to the network operator, the complete repair will take weeks or months.

And that was only a regionally limited outage with a functioning environment that could help. What would happen in the event of a Germany-wide blackout? Who will help then?

Conclusion: Physics beats ideology

A Germany-wide blackout does not last long because German engineers are incompetent. It takes a long time because the power grid is a high-precision, synchronously running machine – and you can’t start machines cold at the same time.

The energy transition ignores this reality. It replaces rotating masses with algorithms, physical inertia with virtual inertial systems, proven black start capability with theoretical concepts. And hopes that everything will work in an emergency.

This is not energy policy – this is Russian roulette with the security of supply of an industrialized country.

The inconvenient truth is that a power grid needs inertia, synchronicity and startability. These are characteristics of rotating machines, not inverters. As long as this basic truth is not accepted, the energy transition will remain an expensive experiment at the expense of security of supply.

The next blackout is sure to come. The only question is: How long will it take for the light to come back on?

Sources and further information:

[1] Federal Network Agency (2020): Monitoring according to § 35 EnWG – Black-start capable plants in Germany https://dserver.bundestag.de/btd/19/167/1916714.pdf

[2] Wikipedia: Schwarzstart – Technical Basics and Procedures https://de.wikipedia.org/wiki/Schwarzstart

[3] Herbert Saurugg (2025): Schwarzstart & Netzwiederaufbau https://www.saurugg.net/blackout/schwarzstart-netzwiederaufbau

[4] Fraunhofer ISE: VerbundnetzStabil – Netzbildende Wechselrichter in Verbundnetzen https://publica.fraunhofer.de/entities/publication/fef7d252-19b0-462d-ab4d-34b36f7d1a79

[5] Cube Concepts (2025): Grid Forming with Grid-Forming Inverters https://cubeconcepts.de/en/grid-forming-mit-netzbildenden-wechselrichtern/

[6] MDPI (2024): Grid Forming Inverter as an Advanced Smart Inverter for Augmented Ancillary Services https://www.mdpi.com/2571-8797/6/3/51

[7] Ingenieur.de (January 2026): Four days without electricity – What the Berlin blackout reveals about our grids https://www.ingenieur.de/technik/fachbereiche/energie/vier-tage-ohne-strom-was-der-berliner-blackout-ueber-unsere-netze-verraet/

[8] Federal Government: Power outage – a risk analysis https://www.bundesregierung.de/breg-de/aktuelles/stromausfall-blackout-2129818

[9] Federal Agency for Civic Education (2023): Are blackouts likely in Germany? https://www.bpb.de/shop/zeitschriften/apuz/blackout-2024/543954/sind-blackouts-in-deutschland-wahrscheinlich/

[10] Next Power Plants: Black Start – How Does the Restart After a Blackout Work? https://www.next-kraftwerke.de/wissen/schwarzstart