Achieving the EU’s decarbonisation targets will require better use of existing energy grids as well as new investments. Identifying infrastructure needs and assessing system adequacy must be based on robust and consistent scenarios that reflect both national and EU objectives. 

To support this effort, ACER publishes a consultancy study aimed at identifying current challenges and areas for improvement in the development of energy scenarios used for long-term infrastructure planning and system adequacy assessments at EU level. This work also supports the broader objectives of the EU’s Action Plan for Affordable Energy, which emphasises the importance of resilient infrastructure and forward-looking investments in strengthening Europe’s economic and energy future.

The study focuses on two key planning processes:

• the Ten-Year Network Development Plans (TYNDPs) by ENTSO-E and ENTSOG; and

• the European Resource Adequacy Assessment (ERAA) by ENTSO-E.

The study’s findings underline the need for better coordination and transparency in the scenario development process, which are key to enabling timely investments that help drive Europe’s energy transition. The study also aims to assist stakeholders, policymakers and decision-makers who use or contribute to these scenarios. 

What are the key findings? 

The study finds that:

• National energy and climate plans (NECPs), which underpin the TYNDPs and ERAA scenarios, often lack sufficient information and clarity. More detailed and easily accessible data would allow for more accurate and consistent scenarios development.

• The timing of the ERAA, TYNDPs and national energy and climate plans is not aligned, raising concerns about the reliability and consistency of the input data, particularly when updated national energy and climate plans are not yet available.

• National energy and climate plans integration into EU-wide scenarios remains partial. Despite recent improvements, there is still no formal validation process to ensure TYNDP and ERAA scenarios accurately reflect NECPs.

• Harmonisation across scenarios used in TYNDPs and ERAA is still limited. Better alignment is needed to ensure consistency across the two exercises. 

• Transparency and stakeholder engagement, particularly in the ERAA process, should be further enhanced. This includes consultations on key input, parameters and assumptions used, clear documentation and publishing of any deviations from national energy and climate plans data.

Interested in the study? 

Register for ACER’s webinar on 11 September 2025 to learn about its main findings and engage with experts.

ACER releases two reports assessing whether the proposed reference price methodologies for the Croatian and Finnish natural gas transmission tariffs comply with the EU Network Code on Harmonised Transmission Tariff Structures.

The reports are addressed to:

• the Croatian national regulatory authority (NRA), Hrvatska energetska regulatorna agencija (HERA); and
• the Finnish natural gas transmission system operator (TSO), Gasgrid Finland Oy (Gasgrid).

ACER finds that Croatia’s proposal makes only minor adjustments to the previous well-functioning methodology (last updated in 2019), while Finland’s proposal retains its existing approach (2020) without addressing some of ACER’s earlier recommendations.

What is proposed?

Croatia proposes to:

• Keep the current postage stamp reference price methodology, with a 60/40% split between entry and exit points.
• Phase out the current tariff discount at the Krk LNG terminal entry point to the transmission system.
• Continue recovering all transmission revenues through capacity-based tariffs.
• Pre-set tariffs for a five-year period, with different tariff levels each year.

Finland proposes to:

• Keep the current postage stamp reference price methodology at domestic exit points.
• Remain in the Finnish-Estonian-Latvian (FinEstLat) market area, applying common entry tariffs and zero tariffs at interconnection points within the area.
• Establish a commodity-based connection capacity charge to recover costs fairly from users that consume gas only during peak periods. 
• Maintain the flow-based charge.
• Apply two non-transmission tariffs: a datahub charge and the Balticconnector underutilisation fee (charged when network users cut back their planned gas flows at short notice, beyond an allowed limit, on days of congestion).

What are ACER’s key findings and recommendations? 

Croatia 

After analysing the consultation document, ACER concludes that:

• The proposed methodology meets EU requirements on transparency, avoidance of cross-subsidisation, non-discrimination, volume risk and prevention of cross-border trade distortions.
• Compliance with the requirements on cost-reflectivity cannot be fully assessed, as it is unclear how the applied economic efficiency justification parameter affects the cost-reflectivity of the allowed revenue.
• The tariff methodologies for non-transmission services (the connection service and the 24 proposed non-standard services) lack sufficient details.

ACER recommends the Croatian NRA to:

• Ensure that the economic efficiency justification parameter does not compromise the principle of cost-reflectivity.
• Clarify how non-yearly bookings are handled in tariff setting.
• Align the tariff period with the Network Code’s requirements.

Finland

After analysing the consultation document, ACER concludes that: 

• The proposed methodology meets EU requirements on non-discrimination, volume risk and prevention of cross-border trade distortions.
• It partially meets the transparency requirements.
• Compliance with the requirements on cost-reflectivity and avoidance of cross-subsidisation cannot be fully assessed, mainly due to a lack of clarity on the effects of the market merger.
• The proposed connection capacity charge does not meet commodity charge criteria due to multiple factors, including its partial application to non-system user entities (e.g. distribution operators and their end-users).

ACER recommends the Finnish TSO to:

• Reconsider the new connection capacity charge to ensure it meets commodity charge criteria.
• Categorise the Balticconnector underutilisation fee as a balancing service, since it falls within the scope of the Network Code on Gas Balancing.

What are the next steps?

ACER encourages the Croatian NRA and the Finnish TSO to take these recommendations into account before adopting the final tariff methodologies.

See all ACER reports on national tariff consultation documents. 

For the second consecutive year, ACER has approved the European Resource Adequacy Assessment (ERAA 2024) proposed by the European Network of Transmission System Operators for Electricity (ENTSO-E). This approval confirms the ERAA as a reliable tool in assessing EU’s security of electricity supply. As its relevance grows, so does the need for continuous improvements in future editions.

What is the ERAA?

The ERAA is ENTSO-E’s annual assessment on the risks to the EU’s security of supply. It provides a 10-year outlook to help policymakers take informed and timely decisions on security of electricity supply. The next edition, ERAA 2025, will be released in November 2025.

What does ACER say about ERAA 2024? 

ACER’s second approval confirms ERAA is a trusted tool for monitoring the adequacy of electricity resources (see ACER’s communication on the ERAA 2023). It highlights how shortages in one Member State can impact others and emphasises the importance of regional solidarity, showing the value of cross-border cooperation in managing scarcity.

The approved ERAA 2024 reflects ongoing efforts to ensure better alignment with the established ERAA methodology. ACER finds that this year’s edition largely meets expectations due to several improvements:

• More robust estimation of cross-zonal capacities using a flow-based calculation method, in line with current industry practice.
• A more representative selection of weather scenarios.
• Closer alignment with the National Energy and Climate Plans (NECPs) for renewable assumptions.

ACER’s suggestions for improving future editions

To ensure the ERAA evolves in line with the methodology and remains a reliable tool for policymakers, further enhancements are needed in three priority areas:

• Reduce the consistency gap between ERAA’s investment and adequacy modules.
• Improve national assumptions’ transparency by explaining the main drivers behind the estimates (especially for demand).
• In future ERAA editions, explain what has changed compared to the previous one, allowing stakeholders to follow the developments. 

Without these improvements, the ERAA gradually risks falling behind. A lack of alignment between its two modules could disconnect market revenues from investment, weakening the tool’s usefulness. Increased consistency and transparency, both long advocated by ACER, are key to meeting the expectations of policymakers and the wider public. For future editions, a full assessment of the existing capacity markets is necessary to contribute to the European Commission’s ‘fast track’ initiative for streamlining the capacity mechanism approval process. 

What are the next steps? 

As ENTSO-E prepares its proposal for ERAA 2025 (expected by November 2025), ACER remains actively engaged with ENTSO-E, Member States, the European Commission and the Joint Research Centre to foster improvements. ACER’s ongoing efforts include:

• Providing insights on ENTSO-E’s preliminary input data, calling for increased transparency (especially regarding demand assumptions, demand response and investment parameters). 
• Commissioning a consultancy study to explore key adequacy and infrastructure challenges in scenario development for the ERAA and the ten-year network development plan (TYNDP). ACER will hold a webinar on 11 September 2025 to present the study (expected in late August).
• Working with ENTSO-E and other stakeholders on streamlining the ERAA methodology, triggered by the related European Commission’s report. ENTSO-E shall propose revisions to the European methodology by mid-October 2025. ACER will then decide on the amendments by the end of January 2026.

Would you like to dive into the topic?

Use ACER’s updated dynamic dashboard to:

• Explore the data categories used in all ERAA’s editions, including those proposed for ERAA 2025. 
• Compare how the estimated electricity demand varies across past editions. 
• Check the estimates for power resources, such as batteries and gas-fired plants in 2030 (and beyond) for each EU Member State.  

On 9 May 2025, the Swedish and Lithuanian national regulatory authorities (Energy Markets Inspectorate and National Energy Regulatory Council, respectively) requested from ACER a six-month extension to reach a joint decision on electricity cross-zonal risk hedging opportunities at the Swedish-Lithuanian border.

On 11 August 2025, ACER has granted the requested extension. The regulators now have until 12 November 2025 to decide on the matter.

What is this ACER Decision about? 

Cross-zonal risk hedging opportunities are strategies used by electricity market participants to mitigate price volatility risks across different bidding zones. They are important for ensuring the proper functioning of EU's wholesale electricity markets and protecting market participants from price uncertainty.

Under the Forward Capacity Allocation Network Code, national regulatory authorities must assess whether forward electricity markets in their respective bidding zones offer sufficient hedging opportunities. If these are deemed insufficient, the regulators must coordinate to either:

• introduce long-term transmission rights (LTTRs); or
• task transmission system operators (TSOs) with implementing alternative measures that enhance cross-zonal hedging.

To meet this requirement, the Swedish and Lithuanian regulators asked their TSOs to propose alternative measures to improve hedging opportunities in the Lithuanian bidding zone. The TSOs submitted a joint proposal to the regulators, but since some aspects were unclear, the regulators requested more time for a thorough review.

ACER’s REMIT Quarterly provides updates on the Regulation on Wholesale Energy Market Integrity and Transparency (REMIT) and related activities, including insights into the 2024 revision of the REMIT Regulation to help stakeholders stay informed on changes that enhance transparency and integrity in the European energy market.

Today, ACER has published its 41^st REMIT Quarterly, covering second quarter of 2025 and the latest developments under the Regulation.

What is in the latest REMIT Quarterly?

This edition highlights the launch of two major transparency tools: the REMIT Data Reference Centre and the Inside Information Access Point, both introduced in May 2025. These ACER applications give public access to non-sensitive market data and inside information, supporting better analysis, oversight and research. A webinar in June presented how to use these new tools.

The report also includes:

• ACER’s ongoing preparatory work on data reporting following the revised REMIT and pending the finalisation of the REMIT Implementing Regulation revision. 
• Key takeaways from Expert Groups' meetings in April and May on Wholesale Energy Market Data Reporting and on Wholesale Energy Market Integrity and Transparency.
• An update on market surveillance and statistics on 416 REMIT breach cases under review at the end of Q2.
• A summary of market activity, showing a year-on-year increase in trading on Organised Market Places, driven by growth in natural gas forward markets.

ACER publishes today its first Recommendation on inter-temporal cost allocation mechanisms for financing hydrogen infrastructure. To ensure the recommendation is well-informed, ACER conducted a public consultation on the topic in spring 2025. 

What is inter-temporal cost allocation and why an ACER recommendation?

The EU aims to build a cost-effective hydrogen network to meet its climate goals. However, high infrastructure costs and demand uncertainty pose significant investment challenges, especially in the early stages of market development.

To address this issue, the EU Hydrogen and Decarbonised Gases Regulation (2024) grants Member States the authority to allow hydrogen network operators to recover infrastructure costs gradually over time through inter-temporal cost allocation mechanisms. These aim to ensure a fair and balanced distribution of costs between early and future consumers, ensuring that the former are not disproportionately burdened.

The regulation also assigns new hydrogen-related tasks to ACER, including issuing a recommendation to guide the development and implementation of inter-temporal cost allocation mechanisms. ACER’s Recommendation provides practical advice to support the rollout of hydrogen networks and ensure fair cost-sharing over the long term. 

What does ACER recommend? 

ACER’s Recommendation identifies key investment risks in hydrogen infrastructure and suggests ways to address them. It offers high-level guidance on designing fair and effective inter-temporal cost allocation mechanisms to support the development of the hydrogen market. ACER also highlights the need for Member States to promptly establish clear hydrogen regulatory frameworks and develop flexible national rules to accommodate the future EU-wide hydrogen network codes.

Given the early stage of the hydrogen market and the lack of established best practices, ACER does not yet propose a single, standardised EU-wide approach. Instead, it calls for:

• Regulatory authorities to:
  • ensure that inter-temporal cost allocation mechanisms and national market rules are developed in a coordinated manner;
  • strengthen cross-border coordination to avoid market fragmentation in the initial stage of the hydrogen market; and
  • establish clear and robust mechanisms that guarantee full cost recovery and fair cost distribution over time to support market growth.
• Network operators and planning bodies to:
  • ensure hydrogen network development is based on transparent, data-driven and realistic assumptions.

What are the next steps? 

ACER will review and update its Recommendation at least every two years, incorporating more refined guidance as the market evolves. The next publication is planned for 2027.

On 2 July 2025, ACER received a proposal from all electricity transmission system operators (TSOs) to amend the methodology for intraday cross-zonal gate opening and closure time. 

What is the methodology about?

Established under the Capacity Allocation and Congestion Management (CACM) Regulation, the methodology sets harmonised rules across EU Member States for when electricity trading can begin (gate opening time) and end (gate closure time) in the intraday market.

The intraday market is a short-term market where electricity is bought and sold on the same day as delivery (e.g. a few hours before), after the day-ahead market has closed. It allows participants to adjust their positions based on updated forecasts and balance supply and demand closer to real time. 

By coordinating these timings across different bidding zones, the methodology supports market integration and the efficient use of cross-zonal capacity within the European electricity market.

Why amend the methodology?

TSOs propose harmonising the gate closure time at 30 minutes before real-time delivery, replacing the current standard of 60 minutes. The gate opening time would remain unchanged. This amendment aims to align the methodology with the requirements of the Electricity Market Design Reform (2024), which seeks to improve the efficiency of short-term markets.

Shortening the gate closure time is expected to:

• allow market participants to trade electricity closer to real time, giving them more time to respond to last-minute changes in demand and supply;
• support the integration of renewable energy sources and flexibility solutions; and
• help TSOs maintain system balance and security of supply.

What are the next steps?

ACER expects to decide on the amended methodology by 2 January 2026.

Interested parties are encouraged to submit comments or questions to ACER-ELE-2025-007@acer.europa.eu by 26 September 2025.

Europe’s clean energy shift is accelerating, and electricity distribution networks must keep pace. From integrating solar panels and electric vehicles to connecting heat pumps and storage, grids need to become more modern, flexible and resilient. To support this, the European Commission’s Action Plan for Grids tasked ACER and the Council of European Energy Regulators (CEER) with providing guidance on electricity distribution planning. 

This guidance provides practical recommendations to help national distribution grid operators align with Europe’s decarbonisation goals and turn grid development into a driver, not a barrier, of the clean energy transition. By promoting more coordinated and inclusive planning, the guidance supports the EU Affordable Energy Action Plan, helping ensure the shift to clean electricity is not only sustainable and secure, but also fair and affordable for all Europeans.

Why grid planning needs a rethink

Distribution networks link homes, businesses and renewables to the wider power grid. Yet most were built for one-way power flows, not today’s decentralised, more flexible generation and fast-growing demand for electricity.

As electrification and renewable growth accelerates, so do the risks of grid bottlenecks and infrastructure development delays. That’s why EU law requires distribution system operators to publish distribution network development plans to outline medium and long-term flexibility needs and investments planned for the next 5-10 years so that the full potential of renewables can be integrated. 

What are the key recommendations? 

• Look ahead: Plan at least 10 years ahead and adopt a proactive approach to avoid grid bottlenecks and enable timely investments.
• Holistic approach: For strategic and efficient results, base electricity grid planning on three pillars: scenario development, network needs assessment and project identification.
• Balance infrastructure and flexibility: Address flexibility needs cost-effectively and ensure national distribution plans provide the necessary input for EU-wide flexibility needs assessment methodology (adopted by ACER today).
• Enhance transparency and public trust: Improve stakeholder engagement through structured publication, open consultations and inclusive communication practices.
• Coordinate: Strengthen cooperation among other system operators and align with broader spatial and sectoral planning to ensure system-wide consistency and efficiency.
• Regulatory oversight: National regulators should scrutinise distribution network development, including monitoring the implementation of plans.