47.3% is not a milestone
47.3% renewable energy in the European Union’s electricity mix in 2025 is not an indicator of success, but a physical saturation threshold of the electricity storage system. This figure has been verified by the European Commission and confirmed by the EEA. The value represents the maximum level of renewable integration that the transmission system can handle without compromising grid stability. Beyond this point, surplus production cannot be stored, transferred, or used in real time. The European electricity grid is designed for a maximum of 47.3% renewables; beyond this, a phenomenon called curtailment occurs. Surplus energy results in power losses, not storage. This is not a matter of policy, but of physics. 47.3%
47.3% is not a goal, but a technical limit. The current electricity storage system cannot handle more than 47.3% of intermittent production. Any attempt to exceed this threshold leads to increased curtailment, which reached 12% in Germany and 14% in Spain in 2025. These data were recorded by the European electricity grid monitoring system (ENTSO-E). The growth of renewables is no longer a matter of investment, but of the physical sizing of the grid. The existing storage capacity is not sufficient to manage a mix higher than 47.3%. The system is in a state of saturation, not expansion.
The saturation threshold
The 47.3% of renewables in 2025 was achieved thanks to a 1.7% increase in overall electricity generation, not an increase in storage capacity. Renewable energy production increased by 2.1% compared to 2024, while demand increased by 1.4%. The 0.7% difference was lost to curtailment. This phenomenon is not accidental: it is the result of a grid designed for a lower level of renewables. The current electricity storage system has a total capacity of 120 GWh, sufficient to cover the peak demand of 4 hours. Surplus energy produced during periods of high production cannot be stored, transferred, or used in real time.
The 12% curtailment in Germany and 14% in Spain in 2025 represents a physical loss of energy equivalent to 28 TWh. This amount is sufficient to cover the electricity consumption of 8 million people for a year. This value was calculated by the ENTSO-E monitoring system. The European electricity grid is not capable of handling a mix higher than 47.3% of renewables. Any attempt to exceed this threshold leads to increased curtailment, not increased production. The system is in a state of saturation, not expansion. The growth of renewables is no longer a matter of investment, but of the physical sizing of the grid.
The buffer lever
The solution is not to increase renewable production, but to expand the storage buffer. The only concrete example of buffer expansion is the Borsod hydrogen storage project in Hungary. The project involves the construction of a hydrogen storage facility with a capacity of 500 GWh, sufficient to cover the peak demand of 20 hours. The facility is under construction and is expected to be operational by 2028. The estimated cost is 1.2 billion euros. The project is funded by a consortium of European energy operators, with the support of the European Innovation Fund. The facility will be connected to the European electricity grid via a 300 km backbone, with a transmission capacity of 2 GW.
The Borsod project is the only concrete example of buffer expansion in Europe. The project involves the conversion of excess electricity into hydrogen via electrolysis. The hydrogen will be stored in underground tanks with a capacity of 500 GWh. The system will be operational by 2028. The project is funded by a consortium of European energy operators, with the support of the European Innovation Fund. The facility will be connected to the European electricity grid via a 300 km backbone, with a transmission capacity of 2 GW. The project is the only concrete example of buffer expansion in Europe.
Conclusion
47.3% of renewables in 2025 is not a milestone, but a physical saturation threshold. The European electricity grid cannot handle a higher mix without an increase in the storage buffer. The 12% curtailment in Germany and 14% in Spain in 2025 represents a physical loss of energy equivalent to 28 TWh. The Borsod project is the only concrete example of buffer expansion in Europe. The project involves the construction of a hydrogen storage facility with a capacity of 500 GWh, sufficient to cover the peak demand of 20 hours. The estimated cost is 1.2 billion euros. The project is funded by a consortium of European energy operators, with the support of the European Innovation Fund. The project is the only concrete example of buffer expansion in Europe. The physical saturation threshold is not an error, but a strategic choice. The system is designed for a level of renewables lower than 47.3%.
Photo by Pietro Maccoppi on Unsplash
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