ACER Opinion 05-2025 on ENTSOG's hydrogen Infrastructure Gaps Identification report 2024

PUBLIC

OPINION No 05/2025 OF THE EUROPEAN UNION AGENCY FOR THE COOPERATION OF ENERGY REGULATORS of 27 May 2025 ON ENTSOG’s DRAFT HYDROGEN INFRASTRUCTURE GAPS IDENTIFICATION REPORT

THE EUROPEAN UNION AGENCY FOR THE COOPERATION OF ENERGY REGULATORS, Having regard to Regulation (EU) 2019/942 of the European Parliament and of the Council of 5 June 2019 establishing a European Union Agency for the Cooperation of Energy Regulators (ACER), and, in particular, Article 11(c) thereof, Having regard to Regulation (EU) 2022/869 of the European Parliament and of the Council of 30 May 2022 on guidelines for trans-European energy infrastructure , and, in particular, Articles 13(3) and 13(6) thereof, Having regard to the outcome of the consultation with ACER’s Gas Working Group, Having regard to the favourable opinion of the Board of Regulators of 14 May 2025, delivered pursuant to Article 22(5)(a) of Regulation (EU) 2019/942, Whereas:

EXECUTIVE SUMMARY

Hydrogen market developments and future challenges

(1) The European hydrogen market is gradually taking shape, driven by ambitious EU-wide strategies and national policies. However, despite the aim for renewable hydrogen set in REPowerEU Plan , significant challenges remain in achieving the 2030 milestones and ensuring a well-functioning market by 2040. These elements are outlined in ACER's Hydrogen Market Monitoring Report , issued in November 2024, which provides a detailed assessment of market trends, barriers, and future developments.

(2) At present, renewable hydrogen consumption is minimal , and while EU decarbonisation goals are expected to drive demand, uptake has been slower than anticipated. Many planned electrolyser projects are awaiting final investment decisions, but deployment faces uncertainties, from demand to future renewable electricity prices. Additionally, the cost of hydrogen produced via electrolysis remains significantly higher than that of hydrogen derived from natural gas , posing financial risks for early adopters.

(3) Given the sector’s strong dependence on policy support and the uncertainties surrounding future demand and supply, assessing infrastructure gaps requires a careful balance between policy aspirations and realistic market needs. Unlike other sectors, such as electricity, hydrogen infrastructure is not yet in place, meaning that the absence of a network itself represents a fundamental gap at every border from the start. In certain cases, infrastructure development in a country may be heavily influenced by demand projections in countries from the region. When demand forecast remains uncertain, this can lead to more cautious and conditional planning approaches, with infrastructure scaled back or delayed until greater clarity emerges.

(4) As the Infrastructure gaps identification (IGI) report is a key tool in this process, intended to provide a trustworthy and robust assessment of future EU hydrogen infrastructure gaps based on demand and supply estimations, this ACER Opinion sets out proposals for further improvements to strengthen the gap identification methodology, with its main findings and recommendations presented below.

Key findings and recommendations

(5) ACER acknowledges the inherent complexity of identifying hydrogen infrastructure gaps, especially given the sector’s early development stage, strong reliance on policy support, and uncertainties surrounding future hydrogen demand and supply. Unlike more mature sectors such as electricity, hydrogen lacks an established network, making the task particularly challenging. ACER commends ENTSOG’s efforts to address these methodological challenges and to deliver analytical outputs under such evolving and uncertain conditions. Furthermore, ACER also appreciates ENTSOG’s ongoing stakeholder consultations and values its efforts to foster transparency and collaboration in the development of the methodology.

(6) ACER notes delay in the delivery of the IGI report, mainly due to Scenarios Report delays, and encourages ENTSOG to make additional efforts in streamline future process and to introduce further improvements to the infrastructure gaps methodology at an earlier stage, using already available data. Furthermore, ACER considers that stronger and more inclusive stakeholder engagement would effectively support ENTSOG in developing an improved methodology, align assumptions, increase transparency, and enhance the credibility of the results.

(7) While ENTSOG’s IGI report already provides indication of bottlenecks hinting at possible infrastructure shortages on certain borders, ACER identifies several opportunities to improve the current infrastructure gaps methodology used by ENTSOG, resulting in a more robust gaps identification. In ACER’s view, one of the most valuable improvements would be a more precise identification of gaps, on a per border basis. Furthermore, a more cross-sectoral modelling approach could help capturing the impact of hydrogen infrastructure on electricity needs, thereby supporting a more coherent and less fragmented network planning. In addition, ACER calls on ENTSOG to include a range of scenarios with sensitivities, where the main hydrogen demand and supply drivers are considered. These scenarios should support the assessment of infrastructure needs under different assumptions, helping to capture uncertainties and identify the appropriate size of infrastructure to meet future needs.

The benefits of a more robust and actionable IGI report

(8) ACER believes that its recommendations would enhance the robustness of future ENTSOG’s assessment of infrastructure gaps, ultimately supporting more efficient investment decisions. Clearer indications on where such infrastructure gaps exist would provide policymakers with better information on the most appropriate projects to meet the identified needs. A well-aligned cross-sectoral infrastructure development approach would allow additional opportunities for system-wide optimisation, leading to more efficient investments across other energy carriers, such as electricity.

(9) By integrating ACER’s recommendations, the IGI report has a potential to fully realise its intended purpose, delivering a robust, and actionable assessment of Europe’s future hydrogen infrastructure gaps. This would not only support well-informed decisions and mitigate investment risks but it would also strengthen stakeholders’ support and contribute to the development of an efficient and cost-effective hydrogen market.

1. INTRODUCTION

(10) Article 13 of Regulation (EU) 2022/869 mandates that every two years, the European associations of transmission system operators for electricity, gas and hydrogen (ENTSO- E, ENTSOG and ENNOH) assess and report on infrastructure gaps within their respective sectors. These infrastructure gaps identification (IGI) reports must be developed within the framework of the Union-wide ten-year network development plan (TYNDP) according to the requirements set forth in Article 13, including an extensive consultation and opinions from ACER, the Commission and Member States.

(11) The first IGI reports must be published within six months following the approval of joint scenarios report developed by the associations under Article 12(6) of the same Regulation. ACER has three months to issue its opinion on the IGI report and submit it to the respective association, the Commission and Member States. After receiving ACER’s opinion, the Commission will have an additional three months to issue its own opinion to the respective association, considering both ACER’s opinion and the input from the Member States. The respective association must then adapt its report taking due account of ACER’s opinion and in line with the Commission’s and the Member States’ opinions and ensure that its final report is publicly available.

(12) Given that ENNOH is not yet formally established, Article 61 of Regulation (EU) 2024/1789 stipulates that, during a transitional period until 1 January 2027, ENTSOG s tasked with developing TYNDP for hydrogen and the associated deliverables, including the IGI report for hydrogen. This process should involve hydrogen transmission network operators and ENNOH, once it has been established.

(13) Considering the above, ENTSOG developed and submitted the draft IGI report for hydrogen for year 2024 (draft 2024 IGI report) to ACER on 10 March 2025, seeking its opinion. The draft 2024 IGI report, along with the results from ENTSOG’s consultation process, is available on ENTSOG’s TYNDP website.

(14) ACER has assessed the draft 2024 IGI report, focusing on its intended purpose to provide a trustworthy and robust assessment of future EU hydrogen infrastructure gaps, noting the specificities of the H2 network development, based on the requirements set forth in Article 13 of Regulation (EU) 2022/869:

• Alignment with established scenarios - The analysis should be based on scenarios developed under Article 12 of the TEN-E Regulation.

• Integration within the Union-wide TYNDP framework - The IGI report must be conducted within the framework of the Ten-Year Network Development Plans (TYNDPs) to ensure consistency with broader energy system planning.

• Focus on EU climate and energy targets - The assessment should prioritize infrastructure gaps that could impact the Union’s ability to meet its 2030 climate and energy targets and its 2050 climate neutrality objective.

• Robust stakeholder engagement - The process must include an extensive public consultation with all relevant stakeholders, followed by a stakeholder feedback report and a summary of how the input was considered.

(15) ACER has also considered its previous opinions, recommendations and positions on 11 12 TYNDP and on TYNDP scenarios , as certain past recommendations remain valid and are reiterated. Moreover, main recommendations should still be considered as key elements for improving the future infrastructure gaps identification process.

(16) Furthermore, ACER has also considered its preliminary feedback document on ENTSOG’s first consultation regarding infrastructure gaps identification elements, calling for further improvements in the methodology.

(17) Based on ACER’s Hydrogen market monitoring report, issued in November 2024, which provides a detailed assessment of market trends, barriers, and future developments, the European hydrogen market is gradually taking shape, driven by ambitious EU-wide strategies and national policies. However, despite the aim for renewable hydrogen set in REPowerEU Plan, significant challenges remain in achieving the 2030 milestones and ensuring a well-functioning market by 2040.

(18) At present, renewable hydrogen consumption is minimal, and while EU decarbonisation goals are expected to drive demand, uptake has been slower than anticipated. Many planned electrolyser projects are awaiting final investment decisions, but deployment faces uncertainties, from demand to future renewable electricity prices. Additionally, the cost of hydrogen produced via electrolysis remains significantly higher than that of hydrogen derived from natural gas, posing financial risks for early adopters.

(19) Given the sector’s strong dependence on policy support and the uncertainties surrounding future demand and supply, assessing infrastructure gaps requires a careful balance between policy aspirations and realistic market needs. Unlike other sectors, such as electricity, hydrogen infrastructure is not yet in place, meaning that the absence of a network itself represents a fundamental gap at every border from the start. A practical example of this challenge is visible in Denmark, where the planned hydrogen network build-out in the Jutland peninsula is heavily influenced by demand expectations in

Germany. Due to the prevailing uncertainty, the initial infrastructure development in the region has been scaled back, with a full built-out now more conditional than originally planned.

(20) The Infrastructure gaps identification report is a key tool in this process, intended to provide a trustworthy and robust assessment of future EU hydrogen infrastructure gaps based on demand and supply estimations.

2. ACER’S ASSESSMENT

Delays in submission of the IGI report

(21) The draft IGI report was submitted to ACER on 10 March 2025. ACER acknowledges this late submission is largely caused by the delays in the 2024 Scenario Report development, which was delayed by circa eight months compared to ENTSO-E’s and ENTSOG’s initial proposal .

(22) ACER encourages ENTSOG to assess the reasons of these delays, propose and implement measures to streamline the IGI report development process to ensure a timely delivery. ACER would see a need the IGI report is delivered by end of the year of the TYNDP process in order to fit PCI/PMI selection process and allow timely analysis of the needs identified for the PCI/PMI selection.

(23) ACER recommends ENTSOG to consider allocating additional resources, including personnel and technological enhancements, to address recurring delays and strengthen its capacity to manage future challenges effectively.

Timing and content of the consultations

(24) ENTSOG conducted the first public consultation on guidance documents for system and project assessment from 19 June to 9 July 2024 and held a public webinar on 24 June 2024. ACER provided its views on the consulted elements and published its response on the ACER website . ACER appreciates ENTSOG took some of the ACER feedback into consideration for further developing elements of the IGI methodology and published the consultation report. However, ACER notes that ENTSOG did not complement the methodology with a proposed indicator for identifying cross-border capacities.

(25) ENTSOG conducted the second public consultation on the draft IGI report and supporting documents from 18 December 2024 to 22 January 2025. A dedicated public stakeholder event was held on 15 January 2025, where ENTSOG presented the draft IGI report. Additionally, ENTSOG published a consultation report outlining how stakeholder

comments were considered, amendments were primarily focused on correcting figures in the tables of the IGI report, without any further revisions to the methodology or recalculations of the results. ACER appreciates that ENTSOG has acknowledged its recommendation and intends to perform additional analysis under the assumption of unlimited hydrogen import capacity. However, as stated in the consultation report, this analysis will only be published in the final IGI report.

(26) Based on the positive experience of the Stakeholder Reference Group (SRG) for the Joint TYNDP Scenarios, ENTSOG may consider establishing a similar dedicated platform for the Hydrogen Infrastructure Gaps Identification process. This would enhance transparency, foster constructive dialogue, and strengthen stakeholder trust by ensuring that the views of impacted stakeholders are adequately considered throughout the methodology development process. Such a platform would likely contribute to a more robust and widely accepted methodology for identifying hydrogen infrastructure gaps.

Use of scenarios

(27) Even though three scenarios were prepared for TYNDP 2024 and covering the years 2030, 2040 and 2050, the IGI exercise was performed only on one scenario for two timehorizon (i.e., NT+ for 2030 and 2040 time-horizons). ACER welcomes the use of NT+ scenario as the central scenario, but further emphasises the need to properly consider future uncertainties, both by extending the analysis to the scenario variants and by adding a sensitivity assessment of the most impactful drivers. In ACER’s view, such approach would provide decision makers with the information necessary to make informed decisions, based on different assumptions regarding hydrogen supply and demand forecasts.

(28) As already stated in its Opinion “on the compliance of ENTSO-E and ENTSOG draft TYNDP 2024 Scenario Report with ACER Scenarios Guidelines” , ACER acknowledges that some assumptions in the TYNDP 2024 scenarios are outdated or not fully aligned with the NECPs . This creates an obvious mismatch as the identified needs as well as inevitably affected by outdated input and cannot be fully consistent with the NECPs. During the PCI/PMI selection process 2025, Member States updated the hydrogen supply and demand forecast for the purpose of System needs methodology,

primarily reflecting a less ambitious hydrogen demand projection for 2040 . ACER emphasizes that any last-minute changes to one of the main scenario assumptions should follow the process outlined in Chapter 6 of the ACER Scenario Framework Guidelines - Guidance for Establishing a Quick Update Process. This would ensure that last-minute modifications to scenario assumptions and data, like Member States’ updates to supply and demand forecasts, are properly considered. Furthermore, incorporating the aforementioned sensitivity assessment of the most impactful drivers, such as hydrogen demand, could enhance the trustworthiness of the final results, as the existing scenario variants, as defined by the Scenario Guidelines, are not necessarily intended to be more or less ambitious regarding hydrogen projections.

Interlinked model

(29) The current modelling approach, which is being used by ENTSOs, involves the development of separate sectoral models (e.g., electricity, gas, hydrogen) by each ENTSO. Individual sectoral models are then combined to form the interlinkages with other sectors. While this approach allows each sector to focus on its unique characteristics, it may also introduce certain limitations and additional steps in the TYNDP process.

(30) In ACER’s view a potential drawback of this method is that the separate models may not always share the same assumptions, infrastructure levels, methodologies, or harmonized approaches in general. This lack of alignment could lead to inconsistencies in outputs, making it more difficult to perform cross-sector analysis or to identify interdependencies between energy carriers. Moreover, the integration process itself could become cumbersome, as differing models may require additional effort to reconcile results, leading to inefficiencies in planning and optimization. Ultimately, while the current approach of modelling may deliver useful outputs for individual sectors, it may fall short in delivering a truly integrated view of system-wide infrastructure planning, particularly in system needs assessment. Since the hydrogen sector has direct implications on electricity grids, potentially requiring reinforcements, these costs should also be considered when analysing hydrogen system needs and vice versa.

(31) ACER calls on ENTSOG to focus, together with ENTSO-E, on further improving sector integration. This should include better harmonisation of assumptions, methodologies and data usage across separate models, as well as ensuring that output approaches are aligned across all sectors to the greatest extent possible. Such improvements would help mitigate the risks of fragmented network development, which is particularly important to avoid, especially as hydrogen sector is still in its early deployment phase and ensure that crosssectoral challenges are addressed more effectively.

Infrastructure gaps identification methodology

2.5.1. Construction and use of Hydrogen Infrastructure Levels

(32) In the current infrastructure gaps identification process, ENTSOG bases its analysis on two assumptions of future hydrogen infrastructure grids. The hydrogen infrastructure model includes a subset of projects submitted by project promoters during the TYNDP 2024 project collection. This subset, referred to as the Infrastructure Level (IL), is defined by the following criteria:

1) PCI/PMI hydrogen Infrastructure Level - includes existing infrastructure, Final Investment Decision (FID) projects, and projects that are part of the 6th PCI/PMI Union list;

2) Advanced Hydrogen Infrastructure Level - builds upon the PCI/PMI hydrogen infrastructure level by incorporating advanced maturity status projects.

(33) ACER proposes to keep the concept of hydrogen infrastructure levels only for the purpose of the CBA process, where projects are assessed based on the estimated hydrogen infrastructure level (reference grid) for the specific simulation year. At the same time ACER underlines the importance of properly reflecting the different purposes of the starting grid for IGI and the reference grids for CBA. ACER believes the IGI starting grid capacities should be built based on currently available transfer capacity, complemented by capacity increases from projects that are in advanced stage and certain to be built, while less-advanced projects should be excluded. As such, ACER recommends that the IGI starting grid should be one, referring to the short-term time horizon and composed only by projects which are in the construction phase and, at the most, projects which have successfully completed the environmental impact assessment. The grid composition for the medium- and long-term horizons would then be the result of an expansion optimisation based on the starting grid.

However, ENTSOG could still assess benefits of these less-advanced PCI/PMI projects during the project assessment phase when applying the CBA methodology. Given the lack of maturity of these less-advanced projects, ACER’s proposed approach would enable a fairer assessment and more realistic estimation of infrastructure gaps.

2.5.2. Proposals for methodology improvements

(34) The Infrastructure Gaps Identification methodology assesses how Europe’s planned hydrogen infrastructure is expected to meet future demand from market integration and security of supply perspective. It aims to identify potential cross-border infrastructure gaps by analysing projected hydrogen supply and demand for two simulation years: 2030

and 2040. The assessment relies on three indicators , one measuring the hydrogen market clearing price spread and two evaluating the reduction of hydrogen curtailment. In addition, the report also includes a comparison analysis of maximum utilisation rates of interconnectors between the two infrastructure levels, indicating potential bottlenecks on certain borders, hinting at possible infrastructure gaps.

(35) While ACER recognizes the added value of such analyses, identifying the problem by providing information on hydrogen clearing market price spreads and hydrogen demand curtailment rates, these indicators are primarily seen as supplementary information and a starting point for analysis of infrastructure gaps. ACER does not consider the proposed indicators as directly relevant for identifying hydrogen infrastructure gaps. Furthermore, drawing firm conclusions based on the interconnector utilisation rates remains challenging, as there is no clear indication of the additional capacities needed per border to mitigate the identified potential bottlenecks.

(36) To strengthen the identification of gaps, ACER recommends implementing an optimisation process, so called network expansion, to determine where optimal crossborder capacities are needed, as a solution to resolve the bottlenecks. After identifying optimal capacity needs, additional results should be presented, demonstrating the benefits of addressing these needs, specifically, the reduction of hydrogen market clearing price spread and curtailment of hydrogen demand in the system.

In this optimisation process ENTSOG should also incorporate unit investment costs for infrastructure to determine the capacity and cost of infrastructure needed to mitigate the bottlenecks. In ACER’s view, such an approach would make the methodology more robust and trustworthy for further system planning and would also ensure further consistency with the well-established electricity Identification of System Needs approach, considering potential deficiencies as identified in ACER’s Opinions on the methodological aspects of the ENTSO-E draft TYNDPs . ACER believes that implementing the proposed improvements would significantly enhance the IGI report’s trustworthiness for network development purposes. Finally, ACER encourages ENTSOG to ensure early consultation on the methodological principles and key assumption parameters for optimisation, such as threshold for price spread differences, demand curtailment thresholds, and unit investment cost values, so that the process is transparent, well-informed, and widely supported.

(37) ACER also suggests reconsidering the inclusion of IGI indicator 2.2, which assesses scenario based on a stressful weather year from security of supply perspective. Given the early stage of hydrogen grid development, such an analysis is deemed premature, as stressful weather years are typically used to assess security of supply risks in sectors with an established market and well-developed infrastructure. At this point, the focus should

be on establishing a sufficient infrastructure that effectively addresses the needs of current assumptions before incorporating extreme weather sensitivities into the analysis. Prematurely factoring in such stress scenarios may lead to misleading conclusions about infrastructure needs, diverting attention from more fundamental challenges in hydrogen network development.

(38) As already stated in ACER’s assessment of the TYNDP 2022 and preliminary feedback on ENTSOG’s guidance documents for system assessment , ACER believes that ENTSOG should consider revisiting its approach for the gaps identification. The main outcome of the gaps identification would be, in ACER view, better expressed in terms of quantified capacities (i.e. how much capacities should be built to address the need of the market and where these capacities could be built). Not showing the results in terms of capacities is making the results of the infrastructure gaps identification much less applicable.

(39) Comparing the resulting capacities with the collected projects would help identify competing projects (in cases where two projects have submitted capacities higher than the target capacities, these projects would be identified as “at least partially” competing) as well as those situations where not enough capacity was submitted to TYNDP by project promoters.

(40) The 2024 IGI report shows that some of the demand curtailment is actually caused by not having enough supply potential that could reach Europe from extra-EU countries like Norway, North Africa, etc., instead of being (solely) caused by capacity bottlenecks within Europe. Therefore, ACER calls on ENTSOG to include an additional analysis in the final 2024 IGI Report by providing simulation results under the assumption of unlimited import capacity from extra-EU countries. By estimating the extent of crossborder infrastructure constraints in the absence of hydrogen supply limitations, given the rest of assumptions remain unchanged, would help isolate the impact of the lack of supply potential from the internal bottlenecks. ACER believes that such an analysis would provide valuable insights into the sufficiency of the planned infrastructure within Europe. Furthermore, the proposed approach should further be consulted with stakeholders as part of the TYNDP 2026 – infrastructure gaps methodology.

(41) Furthermore, ACER sees value in clearly defining expectations for the identification of infrastructure gaps methodology through neutral and transparent guidelines. These guidelines should serve as a basis for the methodology, ensuring that ENTSOG can follow a structured approach before initiating the infrastructure gaps identification process. This could contribute to a more streamlined approach and consistent methodology, ultimately facilitating the timely delivery of the IGI report.

(42) ACER encourages ENTSOG to develop a stable and forward-looking methodology that aligns with ACER’s views and can be applied consistently across future cycles. In

ACER’s view this would minimize the need for frequent adjustments and significantly shorten the development time required, as mainly input parameters would change from one round to the next,

HAS ADOPTED THIS OPINION:

1. ACER acknowledges the inherent challenges in developing hydrogen infrastructure, particularly given the sector’s strong reliance on policy support and the significant uncertainties surrounding future demand and supply. As a result, identifying infrastructure gaps is a complex and evolving task. Unlike more mature sectors such as electricity, hydrogen infrastructure is not yet in place, meaning that the absence of a network itself represents a fundamental gap at every border from the start. Furthermore, ACER recognises ENTSOG efforts in addressing this methodological challenge and producing analytical outputs under these challenging circumstances.

2. Based on the foregoing assessment, ACER notes delays in the submission of the TYNDP deliverables, particularly the TYNDP 2024 Scenarios report, which has also led to the late submission of the IGI report. ACER calls on ENTSOG to assess the reasons of these delays, propose and implement measures to streamline the IGI report development process to ensure a timely delivery in the next process.

3. While ENTSOG’s IGI Report provides indications of bottlenecks hinting at possible infrastructure shortages on certain borders, ENTSOG should consider further improvements for better identification of infrastructure gaps and enhancing the level of granularity needed to support such assessments. Specifically, ACER would see a value in ENTSOG’s strengthening the identification of cross-border capacity needs through the introduction of a network expansion approach, which could offer more accurate cross-border infrastructure gaps assessment. Given the high level of uncertainty surrounding hydrogen market development and its impact on infrastructure development, ACER emphasizes the importance of incorporating scenario variants and sensitivity analyses to better reflect a range of possible future infrastructure needs assessments. This would allow for a more adaptable assessment of infrastructure gaps, while also helping to reduce the risk of misaligned investments. Furthermore, ACER underscores the importance of continued progress in sector integration, particularly given the early development phase of the hydrogen sector, by promoting a coherent and forward-looking multi-sectoral planning approach and identifying the cross-sectoral challenges that as well need to be considered.

4. To address these issues, ACER emphasises that the 2026 IGI report would benefit from the integration of its recommendations to enhance the report’s trustworthiness and usability. In particular, ACER calls for improvements in sector integration through interlinked modelling, the application of a single and more realistic starting grid, the extension of the analysis to include scenario variants and sensitivity assessments of the most impactful drivers. For the identification of infrastructure gaps, an optimisation process should also be considered to determine where optimal cross-border capacities may be required. ACER further encourages more inclusive stakeholder engagement to

support the development of an appropriate methodology, alignment of assumptions, increase transparency, and enhanced credibility of the results. A methodology strengthened by these enhancements would better ensure that ENTSOG’s findings effectively support well-informed investment decisions. Therefore, ACER calls on ENTSOG to implement the proposed improvements outlined in this Opinion, ensuring that the 2026 IGI report is delivered on time and provides a high level of credibility.

5. Finally, to ensure that the infrastructure gaps methodology is ready for the 2026 process, ACER encourages ENTSOG to test the proposed methodology improvements at an early stage, using already available 2024 data, instead of waiting for updated 2026 scenarios. Improving the infrastructure gaps methodology in advance would enable a thorough discussion and validation of the methodology, thereby strengthening its robustness and credibility. Early testing could also help avoid delays and build confidence in the final results. ACER emphasises that this process does not need to follow formal procedures or require any special deliverables, rather, the focus should be on openly sharing and assessing results in a collaborative manner.

This Opinion is addressed to ENTSOG, the Commission and Member States.

Done at Ljubljana, on 27 May 2025.

- SIGNED -

Fоr the Agency The Director

C. ZINGLERSEN

ANNEX I – Information to be published in the final 2024 IGI report

• Simulation results with the assumption of unlimited import capacity as described in paragraph (40) of this Opinion. • Analysis with hypothetical infrastructure approach with a more detailed explanation of the methodology – chapter already indicated in the IGI report. • In the final IGI report, relevant tables should be complemented with units for the lists of borders exceeding the threshold of IGI Indicator 1, as it is unclear whether the figures in the table represent units of days or EUR/MWh. • Additional figures and graphs for a clearer presentation of examples in the Annex D2.

ENTSOG should consider also an improvement of results presentation for the next process by presenting the results in a more interactive format, as an online dashboard, allowing the user to set the parameters/variables and obtain results based on that.