ACER’s 2026 Monitoring Report on energy infrastructure development in Europe examines whether electricity, gas and hydrogen networks are adapting to changing energy needs, and what this means for investment costs, delays and consumer costs.  

As renewable generation expands and electricity demand grows (driven by heat pumps, electric vehicles and data centres), electricity grids need to accommodate new connections and shifting generation and consumption patterns. Meanwhile, gas networks must adapt to lower demand, and hydrogen is still at an early stage. Developing the right infrastructure, efficiently and on time, will determine whether Europe can meet its decarbonisation goals and keep energy affordable for households and industry.

What trends did ACER monitoring find?  

• Electricity grid investment is rising fast. Annual investment in electricity transmission nearly tripled, from €10.4 billion in 2019 to €30.5 billion in 2025.
• Cross-border projects are often delayed. On average, 22% of electricity transmission projects of common interest (PCIs) and mutual interest (PMIs) is delayed each year, mainly due to lengthy permitting procedures. A one-year delay can cost around €4 billion in lost economic welfare.  
• Electricity grid congestion is costly. Remedial actions taken by transmission system operators (TSOs) to relieve congestion cost European consumers €5.4 billion in 2025, over 25% more than in 2024.  
• Income collected to manage electricity grid congestion is largely set aside for later use. Annual congestion income from day-ahead markets exceeded €9 billion in 2025, seven times the 2019 level. Yet, 60% (about €12.5 billion) of the total available is set aside rather than reinvested in cross-border grids or used to reduce tariffs.
• Rising electricity network costs weigh on household bills. Electricity network costs for EU households rose by 40% between 2019 and 2025, reaching 84 EUR/MWh. They now account for around 28% of the average electricity bill.
• Gas networks are adapting to lower demand. Gas investments are broadly stable, while demand remains 16% below its 2017-2021 baseline. Average transmission tariffs increased by 40% between gas years 2020/2021 and 2024/2025.
• Hydrogen networks are at an early stage. EU electrolyser capacity (used to produce hydrogen with electricity) reached 0.49 GW, well below the 30-58 GW target envisaged for 2030 in national strategies and EU scenarios.

What are ACER’s recommendations?  

• Make better use of existing networks through demand response, market-based congestion management, full implementation of the 70% cross-border capacity requirement, cost-reflective network tariffs and grid-enhancing technologies.
• Improve infrastructure planning and delivery with transparent, more integrated planning across electricity, gas and hydrogen networks, and simpler, more predictable permitting procedures.
• Address shortcomings in cost-sharing mechanisms by distributing network costs fairly among users over time and reviewing how costs and benefits of cross-border projects are shared. 

Today, ACER releases its report on the Slovak gas transmission tariffs directed at Eustream, Slovakia’s transmission system operator (TSO).

The report assesses the compliance of the proposed reference price methodology (RPM) with the requirements of the EU Network Code on Harmonised Transmission Tariff Structures (NC TAR). 

Eustream had previously proposed the application of a new tariff methodology for January 2026 to December 2027, with indicative tariffs calculated for that period (see ACER analysis). In April, the Slovak energy regulator, ÚRSO, approved lower transmission tariffs than Eustream had proposed, to be applied from 1 May 2026. Following this decision, Eustream launched a new consultation on 30 June, proposing the same tariffs as in the previous consultation, with only minor methodological changes. 

On 8 October 2026, ÚRSO discontinued the tariff proposal procedure, which also ended the RPM proceeding. There is a 40-day period to appeal against ÚRSO’s decision. The discontinuation of the Slovak procedure does not affect ACER’s obligation to publish its analysis.

What is the proposed tariff methodology?

The Slovak TSO proposes to:

• Introduce a revised methodology and new tariffs midway through the current tariff period, which would result in a tariff increase of more than 50%. The TSO cites exceptional circumstances (a large drop in cross-system flows) as the reason for this change.
• Apply a uniform postage stamp reference price methodology with an ex-ante entry-exit split.
• Continue recovering transmission revenues through a mix of capacity-based charges (paid for reserving network capacity) and commodity-based charges (linked to the volume of gas transported).
• Adjust capacity tariffs at all entry and exit points (including domestic points) using benchmarking to lower tariffs and make them more competitive. Eustream proposes to use a wide set of European TSO tariffs, including those from Northwestern Europe, as a reference.
• Keep two commodity-based charges in place:
  • a flow-based charge paid in kind (meaning a portion of transported gas is normally used to cover the fee); and
  • a complementary revenue recovery charge, designed to help recover the costs of the Slovakia-Poland gas interconnector.

What are the key findings? 

ACER’s findings remain largely unchanged from its February 2026 report. After analysing the new consultation document, ACER concludes that: 

• The proposed methodology meets the EU requirement on non-discrimination.
• Compliance with the requirements on transparency, cost-reflectivity, avoidance of cross-subsidisation, volume risk and the prevention of cross-border trade distortions cannot be confirmed. This is mainly due to the proposed benchmarking adjustment, which does not meet the tariff network code’s standards.
• The proposed commodity-based charges are non-compliant. Specifically, the flow-based charge is corrected by a discount for domestic flows, which is not allowed under EU rules.

What does ACER recommend? 

Should the procedure be resumed, ACER recommends that ÚRSO:

• Limit benchmarking adjustments to points with clear pipeline competition, ensuring tariffs reflect market conditions and remain predictable for network users.
• Implement measures to improve alignment with the network code’s requirements, despite current challenges to full compliance.
• Phase out the non-compliant discount applied to the flow-based tariff.

See all ACER reports on national tariff consultation documents. 

In summer 2026, disruptions to liquefied natural gas (LNG) flows linked to the conflict in the Middle East, low gas storage levels after winter 2025-2026 and slower refilling contributed to tighter supply and pushed the EU’s gas prices higher.

ACER’s latest gas Monitoring Report looks at developments during the 2026 gas summer season and what they could mean for security of supply in winter 2026-2027.

What trends did ACER’s monitoring find?

• EU gas stocks remain below historical levels after a slow summer refill. At the end of winter 2025-2026 underground gas storage levels reached 28% of capacity, down from 34% a year earlier. By 21 October 2026, EU storage stood at 75%.

• Refilling storage has become more expensive. The upper bound estimated cost of refilling storage in 2026 reached €27 billion, while the average cost of injected gas was the second highest in the past decade. The conflict in the Middle East contributed to higher gas prices.

• EU reliance on US LNG continued to grow, as Qatari and Russian supplies fell. US LNG now accounts for around 30% of total EU gas supply, and total Russian gas around 11%. Russian LNG imports are 2% lower than in summer 2025, while Russian pipeline imports fell by 3%. The total EU LNG imports fell by 14%. No significant volumes of Qatari LNG reached the EU in summer 2026. 

• Gas prices rose as Europe competed for LNG in a tighter global market. Spot EU hub prices closed to near EUR 90/MWh mid-October 2026.

• The Middle East conflict added an estimated €18-33 billion to Europe’s gas import bill for the same quantity of gas. These additional costs are spread across the gas value chain, affecting household and industrial consumers and driving up electricity prices. Disrupted Qatari exports through the Strait of Hormuz increased EU reliance on other suppliers, especially the USA.

• Hot weather and droughts during summer increased demand for gas-fired power generation. Gas generation rose by nearly 9% over the gas summer period and by 20% in August compared to the same period in 2025.

Looking ahead

• A tighter winter supply balance: The EU will enter the winter with lower overall storage levels than the nine-year average. Gas demand is around 20% lower since the 2022 gas crisis, increasing the relative value of current storage levels. Weather-driven demand will be impacting the gas storage stocks' evolution.

• The EU is expected to continue to face international competition for securing LNG imports: The EU and Asia will continue to compete for flexible spot LNG cargoes during the heating season, possibly increasing exposure to price pressure and volatility. 

• The EU's winter prospects may lead to higher LNG needs: The actual level of LNG imports needed will ultimately depend on, inter alia, the severity of the winter weather and gas demand. In the current context, additional LNG imports are mainly to come from the USA in view of reduced Qatari supply and the Russian LNG phase-out from January 2027.

As Europe moves towards greater electrification, retail energy markets will increasingly shape the costs and opportunities for consumers. How electricity is priced and how consumers can respond to changing prices will influence whether households can benefit financially from this transition.

The 2026 Monitoring Report on retail energy markets examines electricity bills, affordability and what the shift to electrification means for consumers. 

What trends did the monitoring find? 

• Household retail prices rose sharply after the 2022 energy crisis and have remained elevated. In 2025, EU households spent an average of €840 on electricity and €1,170 on gas.

• Household electricity expenditure ranges from 1.2% to 3.9% of national median income across the EU, reflecting differences in prices, consumption and household income.

• High electricity-to-gas price ratios can weaken the incentive to electrify. Electricity remains relatively expensive compared to gas, discouraging households from switching to electric technologies. Network charges, taxes and upfront costs often widen this price gap further.

• Most consumers are not exposed to the benefits of flexibility. 7% of EU households are on dynamic price contracts, while over 80% in nine countries are on single fixed-term, fixed-price electricity contracts. This limits their exposure to changing price signals and potential savings. Smart meter rollout is also uneven across Member States: 66% of monitored customers have a smart meter, but coverage remains below 20% in several countries.

• Flexible consumption could reduce bills. ACER analysis shows that switching to dynamic pricing and shifting consumption to lower-price periods could have saved households an average of 20% (around €120) on their electricity bills in 2025. 

• Better contract monitoring is needed to assess consumer outcomes. More complete and comparable contract data are key to assessing market impacts on European consumers.

Looking ahead

Electrification will increase electricity consumption and change when and how consumers use energy, creating new challenges for retail energy markets.

Three areas will be particularly relevant:

• Making electrification financially attractive. Retail electricity prices relative to fossil-fuel prices, technology efficiency and upfront investment costs will shape incentives to electrify.  

• Ensuring network investment delivers value for consumers. Efficient planning and use of existing grids will help contain costs and protect electricity affordability as network investment increases.

• Enhancing monitoring of energy retail contracts to understand consumer choice. Better data on the contracts consumers actually choose will help assess whether appropriate price signals and choices are available as consumption patterns change.

Today, ACER published its Opinion on gas and hydrogen national Network Development Plans (NDPs), assessing alignment between national and EU-level planning.

NDPs are national roadmaps prepared by gas transmission system operators (TSOs) and hydrogen network operators (HNOs) across EU Member States. They set out how each country’s networks should develop in the next decade(s) to meet evolving energy needs. Efficient planning helps ensure the right level of network investment, meeting network users’ needs without unnecessary costs.

What is ACER’s role?

Every two years, ACER assesses how well national plans align with the EU-wide Ten-Year Network Development Plan (EU TYNDP), prepared by the European Network of Transmission System Operators for Gas (ENTSOG).

The EU TYNDP is a non-binding plan that sets out how gas and hydrogen infrastructure across Europe could develop over the coming decade, assessing future system needs. It also plays a role in the selection of Projects of Common and Mutual Interest, as candidate projects must be included in the latest EU TYNDP and assessed using its methodologies. This makes alignment between national and EU-wide planning particularly important.

Following its assessment, ACER recommends ways to improve consistency between the two levels of planning, helping coordinate network development across borders and supporting national investments that reflect wider European needs.

What are ACER’s key findings? 

ACER finds that alignment between national and EU-wide planning varies across Member States and sectors. While gas network planning is well established, planning for hydrogen is still emerging.

Three main issues limit closer alignment:

• incomplete institutional frameworks for hydrogen network planning;

• different levels of transparency and approaches to scenarios, infrastructure needs assessments and the inclusion and presentation of network projects; and

• uneven regulatory oversight.

At the same time, ACER identifies progress in several areas:

• Gas transmission networks are adapting to accommodate biomethane, while hydrogen injection into gas networks is permitted more widely.

• Network planning increasingly accounts for the decommissioning and repurposing of existing infrastructure. 

• Market consultations are used more often to inform hydrogen planning.

What does ACER recommend? 

• Strengthen the institutional framework for national plans, adopting a biennial planning cycle aligned with the EU TYNDP process, and ensuring effective regulatory oversight of NDPs, including their approval and amendment.

• Improve transparency on planning methodologies, regulatory assessments and important project information (e.g. costs), and strengthen stakeholder and market consultation, particularly on future hydrogen demand.

• Enhance cross-border and cross-sectoral coordination, improving cooperation and data exchange between system operators and better aligning national and EU-level planning scenarios.

• Better integrate decarbonisation measures, ensuring that NDPs reflect the most recent changes in the gas and hydrogen sectors, including infrastructure decommissioning, the repurposing of gas infrastructure for hydrogen and biomethane injection projects.

What are the next steps?

ACER invites Member States and system operators to consider its recommendations to make network planning more consistent and transparent.

The next ACER Opinion will be published in 2028.

Today, ACER releases its report on the Irish gas transmission tariffs directed at the Commission for Regulation of Utilities (CRU), Ireland’s national regulatory authority (NRA).

The report assesses whether the proposed reference price methodology (RPM) complies with the requirements of the EU Network Code on Harmonised Transmission Tariff Structures (NC TAR). 

What is the proposed tariff methodology?

The Irish NRA proposes to:

• Apply a forward-looking matrix methodology based on marginal expansion costs, allocated between entry and exit points. Under this approach, differences between tariffs at network points would reflect the expected unit cost of expanding the pipeline, rather than historical costs.

• Apply the same tariff to all exit points serving domestic consumption and a single tariff to all future renewable gas production points, regardless of their location.

• Set rules on tariff discounts for any future storage and LNG facilities.

• Continue recovering allowed revenues for transmission services through a combination of capacity- and commodity-based tariffs. Capacity tariffs are charged for contracted network capacity, while commodity tariffs are based on transported gas volumes and recover the related costs.

• Treat the Corrib Linkline (the pipeline connecting the Corrib offshore gas field to the main ring of the Irish gas network) separately from the transmission service, recovering its costs through a separate tariff.

What are ACER’s key findings? 

After analysing the consultation document, ACER concludes that: 

• The proposed methodology meets the EU requirements on cost-reflectivity, transparency, avoidance of cross-subsidisation, non-discrimination, volume risk and prevention of cross-border trade distortions.

• The criteria for setting the flow-based charge are also met.

• The criteria for setting non-transmission tariffs are not fully met, as the Corrib Linkline is treated similarly to a non-transmission service but not formally classified as such.

• The capacity forecasts used in the methodology are based on Ireland's Network Development Plan for 2024, which may not fully capture more recent demand shifts.

What does ACER recommend? 

ACER recommends that the Irish regulator, when adopting its final decision:

• Improve the description of the revenue and tariff structure of the Corrib Linkline and formally classify its use as a non-transmission service.

• Update capacity forecasts using more recent estimates and, if these show cross-system flows, reassess the methodology against the relevant NC TAR principles.

ACER also recommends that, as part of its upcoming review of the tariff methodology, the Irish regulator assess whether a methodology based on forward-looking marginal expansion costs remains appropriate in the context of the energy transition and declining gas demand.

Next steps

The Irish NRA has until 16 December 2026 to adopt a motivated decision on the reference price methodology.

See all ACER reports on national tariff consultation documents. 

ACER has issued a favourable Opinion on the decisions by the Austrian and Slovenian energy regulators to prolong the existing exemption from establishing physical bi-directional capacity at the Murfeld/Ceršak interconnection point between the two countries. The renewed extension would run until November 2029.

The extension was proposed by the Austrian and Slovenian transmission system operators (TSOs) and approved by the national energy regulators. After reviewing the coordinated decisions, ACER endorsed the proposal.

What is bi-directional gas flow capacity?

Under the European Security of Gas Supply Regulation, TSOs must establish permanent physical capacity for gas transport in both directions (bi-directional capacity) at all cross-border interconnection points between Member States.

Where building this bi-directional capacity is not justified, temporary exemptions may be granted following a detailed assessment and consultation with stakeholders, other Member States and the European Commission.

What is ACER’s assessment?

• The TSOs carried out the consultation and decision-making process in a timely and coordinated manner.
• The coordinated decisions comply with the Regulation’s requirements and justify prolonging the exemption.
• Current market signals do not indicate a need for bi-directional capacity from Slovenia to Austria.
• Building such capacity without market demand would result in inefficient investments, as costs would significantly outweigh the expected benefits for Austria’s security of supply.

On this basis, ACER considers the four-year extension justified, provided there are no significant changes in market conditions or infrastructure developments in the meantime.

What are the next steps?

ACER has submitted its Opinion to the Austrian and Slovenian energy regulators, as well as to the European Commission.

Within four months of receiving ACER Opinion, the European Commission may request modifications to the decisions.

ACER’s new retail energy markets dashboard offers an interactive, country-by-country view of electricity and gas markets across the EU and Norway. It replaces ACER’s country sheets, bringing together comparable data to explore how retail markets are evolving and how consumers’ behaviour changes alongside the energy transition.

What trends did ACER monitoring find?

With over 270 million electricity and more than 90 million gas customers across the EU and Norway, retail energy markets play an important role in supporting Europe’s energy transition. At the same time, the latest data shows ongoing challenges and significant untapped potential for more active consumer participation.

• Energy bills remain above pre-crisis levels. Retail prices rose sharply after the 2021-2022 energy crisis and remained elevated, with gas prices still nearly 70% higher than before the crisis. On average, EU households spent around €840 on electricity and €1,170 on gas in 2025.
• Household electricity and gas consumption is rising modestly, highlighting the importance of enabling consumers to actively manage their energy use.
• Fixed contracts remain the most common contract type. Around 52% of household electricity customers are on single fixed-price, fixed-term contracts, while only 7% are on dynamic-price contracts, pointing to significant unexploited capacity for demand-side flexibility.
• Smart meter rollout progresses unevenly. 66% of household customers monitored across the EU and Norway have a smart meter. While deployment exceeds 80% in most EU Member States, it remains below 20% in several countries, limiting consumers’ ability to adjust their consumption in real time.

What are the next steps?

The retail energy markets dashboard will be updated annually as new data becomes available, allowing to monitor progress across all indicators.

ACER publishes today its Opinion on the draft TYNDP 2026 Scenarios Report prepared by the European Network of Transmission System Operators for Electricity and Gas (ENTSO-E and ENTSOG) under the TEN-E Regulation. 

These scenarios, produced every two years, provide the common foundation for EU-wide electricity, gas and hydrogen infrastructure planning, and feed into the Ten-Year Network Development Plans (TYNDPs).

ACER’s Opinion assesses whether the ENTSOs’ scenarios comply with ACER’s Framework Guidelines and provide a transparent and consistent basis for infrastructure planning.

What are the key findings?

ACER welcomes the significant work by ENTSO-E and ENTSOG to improve the scenarios’ accuracy, including:

• the continued delivery of joint scenarios combining electricity, gas and hydrogen; 
• the introduction of economic variants (high- and low-growth cases applied to the central scenario to assess the robustness of the underlying economic assumptions);
• the involvement of the Stakeholder Reference Group, which gives stakeholders structured scrutiny over the scenarios’ assumptions, methods and data; and
• the development of an Innovation Roadmap, which sets out planned improvements to the scenario-modelling tools and methods, and is updated every two years.

ACER also identifies two main areas for improvement:

• Alignment with EU climate and energy targets. The current methodology enables formal compliance with EU targets, but ACER considers that it does not adequately capture the structural changes needed to achieve those targets in practice.
• Stronger economic variants. These should function as meaningful alternative scenarios, with greater transparency and consultation on key scenario assumptions and infrastructure planning inputs, improved consistency with the European Resource Adequacy Assessment (ERAA) and a more timely scenario development process.

What are the next steps?

For the finalisation of the TYNDP 2026 Scenarios Report, ACER calls on ENTSOs to improve transparency on the remaining gap to EU climate and energy targets and the limitations of the current methodology.

For future cycles, ACER expects further improvements in EU targets alignment, economic variants, consistency with ERAA, stakeholder consultation and the overall timeliness of the process.

The European Commission will take ACER’s Opinion into account when assessing the draft TYNDP 2026 Scenarios Report.

In its Summer Supply Outlook 2026, the European Network of Transmission System Operators for Gas (ENTSOG) evaluates the evolution of gas supply and assesses whether the EU’s gas system can meet demand, support exports and storage injections over the summer under normal market conditions.

The Outlook also includes an analysis of supplies and storage inventories to assess security of supply for winter 2026/27 and evaluates the system’s resilience under different stress scenarios, including supply disruptions.

ACER acknowledges the storage-filling challenges identified by ENTSOG. As this year’s reference scenario does not introduce major methodological changes compared with previous editions (extensively reviewed by ACER), ACER is not issuing a formal opinion on the 2026 edition.

What are the main highlights of the 2026 Summer Supply Outlook?

ENTSOG's assessment identifies several developments that will shape the EU’s gas system over the summer season:

• Low storage levels: At the start of the gas summer season (1 April 2026), average EU gas storage stood at 28% capacity, below the levels recorded at the start of the previous three summer seasons.
• High LNG demand: Refilling storage to the 90% target before winter (by 1 November) will require greater use of the EU’s gas infrastructure and higher liquefied natural gas (LNG) imports than in previous years. At the same time, ENTSOG notes that EU Gas Storage Regulation provides some flexibility, allowing a lower filling target.
• Supply disruption risks: The ongoing conflict in the Middle East is pushing up gas prices and narrowing the usual summer-to-winter price gap. This weakens the economic incentive for gas storage injections, which could further slow refilling.
• A resilient system: The EU’s LNG regasification capacity is expected to help compensate for lower storage levels and support winter demand, provided adequate LNG supplies are secured.

What are ACER’s main considerations?

ACER highlights the challenges ahead, as identified in ENTSOG’s assessment:

• The EU will need higher LNG imports. ACER’s latest analysis of European gas wholesale markets (winter 2025/2026) confirms that the EU’s LNG imports will need to rise by around 13% over 2025 levels to meet summer demand and reach the 90% filling target before winter, while the 80% target remains achievable with 2025 LNG import levels. This reflects LNG’s growing role in the EU’s energy mix: it covers around half of total gas imports, making the EU the world’s largest LNG importer (see also ACER’s analysis of European LNG market developments in 2025).
• Market conditions are weakening storage-filling incentives. Storage refilling could become more challenging in the months ahead. Unfavourable winter–summer price spreads, the phase-out of short-term Russian LNG and pipeline gas contracts under the REPowerEU Gas Regulation (from 25 April and 17 June 2026, respectively) and continued volatility due to the Middle East conflict constrain the supply available for storage, increasing the pressure to accelerate injections before November.
• Current data point to tight storage conditions:
  • Storage injections are below both the 10-year summer average and 2025 levels, putting the refilling timeline at risk (see Figure 1). 

  • EU gas storage is currently at around 49% capacity, similar to 2021 levels (see Figure 2).

Given these risks, ACER encourages Member States and their competent authorities to closely monitor storage-filling trajectories in the months ahead and foster continued progress, actively managing risks in compliance with the Gas Storage Regulation.

Looking ahead

ACER welcomes ENTSOG’s ongoing monitoring of storage injection trajectories and LNG import availability, as geopolitical instability continues to affect global energy markets.

For future Outlooks, ACER underlines the importance of continuing to assess how planned and unplanned gas supply disruptions may affect the EU’s ability to meet its storage-filling targets.

Finally, ACER highlights the need for timely storage injections in the coming months.

See all ACER’s reactions to ENTSOG’s Supply Outlooks.