Europe’s electricity grid is undergoing one of the most profound transformations in its history. The electrification of the economy, the rapid growth of renewable energy sources and the need to strengthen energy security are forcing a redesign of the infrastructure that underpins the continent’s power supply.

This is one of the key conclusions of ENTSO-E’s 2025 Annual Report, published this week. The association representing Europe’s transmission system operators identifies grid reinforcement, enhanced system flexibility and stronger operational resilience against increasingly complex incidents as some of its main priorities.

One of the most significant milestones of the year was the synchronisation of Estonia, Latvia and Lithuania with the Continental Europe Synchronous Area, completing a decade-long process that reduces the Baltic states’ historical dependence on eastern power systems while strengthening European energy integration. The synchronisation process began on 9 February 2025 and was officially completed in November after all technical requirements established by European operators had been fulfilled.

The integration of electricity systems has become one of the cornerstones of Europe’s energy strategy. According to ENTSO-E, since the first Ten-Year Network Development Plan (TYNDP) was published in 2010, more than 16,000 kilometres of new transmission infrastructure have been built, while 23 EU Member States have added at least one new international interconnection.

The grid challenge

The report warns that the energy transition cannot be completed without a significant expansion of electricity grids. In January 2025, ENTSO-E released the 2024 edition of its TYNDP, highlighting the need for large-scale investments in both national and cross-border grids, while identifying permitting delays and supply-chain constraints as growing risks for infrastructure deployment.

The organisation stresses that planning must be accompanied by faster implementation in order to meet the expected increase in electricity demand resulting from the electrification of transport, industry and heating.

Flexibility for a renewable Europe

ENTSO-E considers flexibility to be one of the defining features of Europe’s future power system. The growing share of variable renewable generation requires the development of new demand-side management tools, energy storage solutions, flexibility markets and advanced digital systems.

To support this objective, ENTSO-E worked throughout 2025 with the EU DSO Entity on methodologies to assess flexibility needs across European power systems, as well as on projects related to data interoperability and the future European electricity grid digital twin.

The year of the Iberian blackout

The report was also shaped by several major incidents affecting Europe’s electricity system.

Following the blackout that affected Spain and Portugal on 28 April 2025, ENTSO-E established an independent panel of experts to investigate its causes. The panel’s factual report, published on 3 October, provided a minute-by-minute reconstruction of the event, system conditions and the restoration process.

In addition to the Iberian blackout, ENTSO-E investigated other significant incidents in North Macedonia and the Czech Republic, further reinforcing its focus on resilience and operational security.

Graphic by Review Energy based on ENTSO-E data

Preparing the Future While Managing the Present

ENTSO-E’s strategic roadmap is built around two core pillars: preparing a power system fit for a carbon-neutral Europe while simultaneously ensuring the security and efficiency of today’s electricity system.

To achieve these goals, the association sees accelerating grid investments, expanding storage capacity, modernising market design, digitalising operations and strengthening regional coordination as top priorities. The ultimate objective is to create a power system capable of integrating large volumes of renewable generation without compromising stability or security of supply.

Source: ENTSO-E’s 2025 Annual Report

The report’s conclusion is clear: Europe’s energy transition is no longer solely about deploying more renewable capacity. The success of decarbonisation will depend largely on Europe’s ability to build new grids, unlock greater flexibility and strengthen the resilience of an increasingly complex and interconnected electricity system.