Europe's new summer energy challenge: the 'Hitzeflaute'
Extreme heatwaves are creating significant stress on Europe’s energy infrastructure. I came across an interesting article by Julien at GEM Energy Analytics that clearly explains this growing challenge. He introduces the German term Hitzeflaute, which describes a period of intense heat with little to no wind.
The challenge of a hot, still day
For years, the energy sector has discussed the Dunkelflaute, a dark, windless period in winter when both solar and wind generation are low. The Hitzeflaute is its summer equivalent, though slightly different.
During a hot, windless period, solar panels generate a large amount of electricity during the day, which helps to meet the high demand from air conditioning. The problem, however, shifts to the evening. As the sun sets, solar generation drops to zero, but temperatures remain high, and so does the demand for cooling. With no wind to support, the grid is faced with high demand and low renewable supply.
The impact on energy prices
This predictable evening scarcity has a direct effect on electricity prices. As demand exceeds the available renewable supply, the system must rely on more expensive power sources, causing prices to spike for several hours.
This volatility leads to extremely high imbalance prices: the costs paid to balance the grid in real-time. These prices are a clear indicator that the system is operating under significant stress. The article highlights that these price peaks are becoming a structural feature of our modern, renewables-heavy grid.
At first, this seems counterintuitive. If we can predict this evening scarcity, why are the prices so high? The simple answer is that knowing a problem is coming is not the same as having enough cheap tools to solve it. When the sun sets, the grid must instantly replace a massive amount of solar power. We currently do not have enough large-scale battery storage to save cheap daytime energy for the evening. Therefore, the system must rely on expensive backup power plants. The high price reflects the cost of this scarce, last-resort solution needed to keep the lights on.
What can Europe do?
The good news is that these challenges have solutions. The price signals are sending a clear message about where investment and innovation are needed. The article suggests several key areas of focus:
- Increased flexibility and storage: Battery storage is ideal for solving this kind of short-term problem. It can absorb cheap, abundant solar power during the day and release it during the evening peak, flattening the price curve.
- Smarter demand management: Encouraging consumers to shift their energy use away from peak hours (load shifting) can significantly reduce strain on the grid.
- Better grid interconnection: Strengthening connections between countries allows electricity to flow from areas with a surplus to areas with a deficit, increasing overall system resilience.
A systems engineering perspective
From a systems engineering viewpoint, this is a classic optimisation problem. The grid is a complex system that must be designed for resilience against predictable events like heatwaves.
The article notes that some power plants are offline for maintenance during summer, which is traditionally a period of lower demand. This is where predictive maintenance can help. By predicting potential failures, maintenance can be scheduled more strategically. For instance, instead of a fixed annual shutdown, a gas plant’s maintenance could be dynamically scheduled based on long-term weather forecasts and real-time sensor data. This data, from sensors monitoring things like turbine vibration, operating temperatures, and component stress, helps predict wear and potential failures. This approach ensures that essential backup power plants are available during these high-stress heatwave periods, rather than being offline when they are needed most.
Wrap-up
The “Hitzeflaute” demonstrates how Europe’s power system is now shaped as much by the climate as it is by technology. These events are no longer rare disruptions but regular stress tests.
