The recent severe power cut in Spain and Portugal on 28 April 2025 makes us all start to think: How secure is actually our electricity supply? How vulnerable are we if there is a sudden interruption of power supply that may last for longer? As recent reports show, the huge power cut in the Iberian Peninsula this year was actually the first of its kind: It was not caused by a cyber attack, neither by equipment failure, but it was a cascading effect triggered by a sudden drop in electricity generation and insufficient voltage control to handle this imbalance. In other words, the complexity of the power grid itself and the control of its components was the root of the problem.

The International Energy Agency (IEA) defines energy security as the uninterrupted availability of energy sources at an affordable price. Power grids and their frequency and voltage dynamics have an enormous complexity, and the control of a stable power supply is far from trivial, though of course absolutely essential for our modern civilization. Power grids are in fact the biggest machines on Earth, they are much bigger than, for example, the Large Hadron Collider (LHC) or other collider experiments when it comes to size. The interconnected power grid of Europe spans 4,000 kilometres. These biggest machines on Earth are also the most complex ones, as they are based on a nontrivial network topology and as they couple to humans, with their strongly varying consumption behaviour. Not only the demand, but also the power generation process is highly intermittent due to the large fraction of renewable energy generation in the energy mix: If the wind blows stronger, more power is generated.

It is not surprising that more and more physicists from the statistical physics and complex network community have started to work in this scientifically very interesting area of complexity, fluctuations and stability properties associated with power grids that contain a fairly large fraction of renewables. This research can complement the large amount of knowledge from the engineering sciences with new models inspired by physical ideas. Besides statistical physicists also physicists from other areas yield valuable contributions in this area. For example, chemical physicists are interested in new affordable battery solutions or other methods to smoothen the fluctuating power production and demand patterns, both on short and on long time scales. And solid state physicists are interested in developing even cheaper solar panel solutions.

In the following we have three different articles that connect to this field: Rydin Gorjao et al. describe fluctuations and control of the power grid frequency and the relation to a typical physics textbook topic---the overdamped harmonic oscillator, but this time with very complicated driving forces as generated by the complex environment in which the power grid is embedded. Wedemeyer et al. look at how space weather events can severely hurt critical infrastructure on Earth, including that of power grids. Finally, the article by Obradovic et al. describes a particular method to smoothen demand and production patterns in terms of nitrogen fixation. These and many other physics-inspired ideas will help to work towards a reliable and sustainable energy supply of the future.

© European Physical Society, EDP Sciences, 2025