In summer 2024, Southeast Europe¹ experienced a sustained period of electricity price spikes. In response, the European Commission asked ACER to assess which measures could help prevent or mitigate similar episodes across the region in the future. 

Today, ACER publishes its Monitoring Report to the Energy Union Task Force, setting out recommendations to increase cross-zonal capacity and system flexibility across Southeast Europe.

What did ACER find? 

• The 2024 price spikes were driven mainly by a lack of flexible resources to replace solar generation in the evening, during periods of high demand. 
• Limited cross-border capacity, including due to planned network maintenance, reduced the region’s ability to import lower-priced electricity from the rest of the EU.
• Although prices in 2025 did not reach the same levels as in summer 2024, the price gap between Southeast and Central Europe² persisted into early 2026. This suggests deeper structural challenges in the region. 

ACER found that a better use of the existing network could have helped ease regional system stress in 2024. But increasing interconnection alone is not enough – greater system flexibility is also key. 

What does ACER recommend?

Addressing the challenges observed in Southeast Europe’s electricity markets requires both immediate and long-term action by Member States, national regulatory authorities, transmission system operators and other market actors:

• Faster deployment of grid-enhancing technologies (such as dynamic line rating and advanced line conductors).
• Improved regional coordination, including on outage planning and curative remedial actions in capacity calculation. 
• Continued implementation of EU market integration rules (minimum 70% cross-zonal capacity requirement, flow-based approach across Southeast and Eastern Europe, and market coupling with non-EU neighbours).
• Accelerated network investment projects to strengthen interconnectivity of Southeast Europe.
• Measures to unlock system flexibility by removing market barriers for small market participants and supporting investments in flexibility.
  
  ^{1. For the purpose of this assessment, Southeast Europe refers to the group of Member States affected by the price spikes: Slovenia, Croatia, Hungary, Romania, Bulgaria and Greece. 2. Central Europe refers to Austria and Slovakia.}

Today, ACER publishes a policy paper exploring how Europe could improve the way costs and benefits of cross-border electricity infrastructure projects are shared. The paper aims to support the grid investments needed for a more integrated European electricity market and a more efficient use of Europe’s electricity system. 

Why cost and benefit sharing of energy infrastructure matters

Building an integrated European electricity market requires substantial cross-border grid investments. An effective cost-sharing framework is a key enabler of such investments, especially when infrastructure in one country brings benefits beyond its borders.

However, the current framework does not always ensure that costs are shared fairly when a project benefits several countries (for example, when one country bears most of the investment costs while others receive a significant share of benefits). 

As a result, projects with clear European or regional value might not be realised if costs are largely borne at national level while benefits are distributed more widely across borders.

Several mechanisms currently aim to address this challenge: 

• congestion income distribution, which shares revenues from cross-border congestion; 

• the inter-TSO compensation (ITC) mechanism, which compensates for costs related to hosting cross-border flows; and 

• cross-border cost allocation (CBCA), which allocates costs of new infrastructure based on expected cross-border benefits. 

While each plays an important role, gaps and overlaps remain in how effectively they align costs with benefits. This can make it more difficult to develop infrastructure that is valuable from a European or regional perspective.

What is in ACER’s policy paper?

Already in July 2024, ACER committed to strengthening and improving the existing mechanisms to better reflect the costs and benefits of cross-border network infrastructure. 

As part of this effort, ACER’s 2026 policy paper assesses the current mechanisms, their gaps and overlaps, and explores how they could be improved or redesigned to better align national investments with European and regional needs. 

It sets out several policy options, ranging from targeted improvements to the existing mechanisms to broader changes to the overall cost-sharing framework. These include improving the current mechanisms separately, combining some of them into a single ex-post mechanism, or exploring a new framework with common EU financing for infrastructure used for cross-border trade. 

The policy paper also provides a qualitative evaluation of these options, with the common objective of strengthening investment incentives for cross-border electricity infrastructure.

The policy paper does not provide definitive solutions to the identified challenges. Instead, it aims to inform and stimulate further discussion on how the cost-sharing framework can better support investment in projects of European and regional value. 

ACER has published its 2026 Monitoring Report on European liquefied natural gas (LNG) market developments, reviewing key market trends in 2025 and the implications for Europe’s energy security, including the risks linked to tensions in the Middle East.

Worth highlighting, given there is much talk of EU data gaps, that ACER has the overview of EU LNG market. This annual ACER report shows that LNG has become central to the EU gas system as Europe continues to move away from Russian gas. At the same time, it highlights growing exposure to global LNG market risks, including supply concentration, spot market volatility and geopolitical disruptions.

Main highlights

• The EU imported a record 146 bcm of LNG in 2025, confirming LNG’s key role in Europe’s gas supply. The EU is the world's largest importer of LNG.
• Global LNG production increased by 36 bcm, the strongest annual growth since 2022.
• The United States supplied 58% of EU LNG imports in 2025, equivalent to around a quarter of total EU gas demand.
• ACER’s daily LNG price assessments (based exclusively on actual spot transactions) provide much needed transparency on the EU LNG spot price discovery. More than 980 spot LNG cargoes for delivery in the EU in 2025 were reported to ACER in 2025, up from 550 transactions in 2024.
• TTF, the Dutch gas trading hub, remained the main benchmark, used to price 74% of EU spot LNG trades.
• In a full-year Strait of Hormuz closure scenario in 2026, the global LNG market could face a net supply shortfall of 27 bcm compared with 2025, intensifying competition for spot cargoes.

ACER’s recommendations

Recent tensions in the Middle East show how quickly geopolitical crises can disrupt energy flows and drive up prices. In response, ACER underlines the continued strategic importance of REPowerEU and its three pillars for Europe’s energy security:

• Energy savings and efficiency, to reduce gas demand and lower vulnerability to external shocks.
• Diversification of supply sources, to avoid overreliance on individual suppliers or transit routes.
• Faster roll-out of renewable energy, to strengthen resilience by reducing dependence on imported fossil fuels.

For punchy overview of related issues like the impact of Hormuz on EU gas storage filling for winter 2026, see also the recent ACER key developments in European gas markets report (April 2026). 

Today, ACER releases its Opinion on the All-Island Resource Adequacy Assessments for Ireland, Northern Ireland and the Single Electricity Market (SEM) as a whole. The assessment was jointly prepared by the transmission system operators (TSOs) of both jurisdictions (EirGrid and SONI), complementing the European Resource Adequacy Assessment (ERAA) 2025.

What is a resource adequacy assessment?

The ERAA evaluates electricity resource adequacy across the EU and provides a consistent framework to assess whether additional national measures are needed to ensure security of supply. It is carried out annually by the European Network of Transmission System Operators for Electricity (ENTSO-E) and reviewed by ACER.

Member States can complement the European analysis through national adequacy assessments (NRAAs) to reflect local conditions. When a national assessment identifies differences from the European assessment, ACER issues an opinion.

What did ACER find?

ACER finds that most differences between the All-Island Resource Adequacy Assessment and the ERAA are justified, as they reflect national trends and include additional modelling detail, enhancing accuracy. 

ACER also highlights two factors with a major impact on adequacy:

• The planned second North-South Interconnector is included only in the SEM-wide assessment, meaning its contribution to adequacy is not captured in all three analyses. Once operational (expected by 2031), it would help keep adequacy risks in the SEM within the reliability standard in 2033 and 2035, strengthening security of supply across the island and highlighting the importance of increased cross-zonal capacity for resource adequacy.
• The rapid growth of data centres in Ireland (which accounted for 22% of national electricity demand in 2024 and could reach 31% by 2034) poses a key adequacy risk. New policy updates now require data centres to provide onsite or nearby generation equal to peak demand, helping reduce grid reliance and improve flexibility during stress periods. Future adequacy assessments should better reflect both the demand impact of data centres and the extent to which policy measures can mitigate adequacy risks.

What are ACER’s recommendations?

To further strengthen the assessment, ACER recommends that TSOs:

• Include a viability assessment of adequacy resources in the central scenario to confirm the required resources are realistically available. 
• Ensure revenue consistency between market viability and dispatch models so that both tools reflect aligned market revenues and investment signals. 
• Consider multiple revenue streams in the assessment to provide a more robust evaluation of resource profitability. 
• Include the planned second North-South Interconnector in all the three analyses. 
• Consider greater operational flexibility for gas units during periods of scarcity. 
• Incorporate storage and demand response expansion, including flexibility from data centres, for all target years till 2035. 

What are the next steps?

ACER encourages TSOs to consider these recommendations to ensure a more accurate assessment of adequacy risks.

Europe has an EU-wide framework (called 'REMIT') to detect and deter market manipulation and abuse in wholesale energy markets. This framework counts on many parties collecting and monitoring data, all working together to ensure the integrity of Europe’s wholesale energy markets. National energy regulators are responsible for REMIT enforcement.

Today, ACER publishes its annual reports on energy market surveillance, covering:

• The preparedness of persons professionally arranging transactions (PPATs) to detect and report suspicious behaviour. PPATs are trading intermediaries such as energy exchanges, organised market places (OMPs) or brokers, who arrange or facilitate transactions in wholesale energy products.

• National regulatory authorities’ (NRAs’) analysis of suspicious transaction and order reports (STORs) submitted by PPATs, their enforcement actions and penalties.

Both reports are mandated by the 2024 revised REMIT Regulation, which expanded PPATs’ obligations for monitoring trading activity and reporting suspected market abuse to ACER and to the relevant national regulator.

What are ACER’s key findings?

ACER highlights the important role of PPAT market surveillance and NRA enforcement under the REMIT framework. 

ACER’s analysis shows that PPATs’ structural compliance with their REMIT obligations is improving. However, their market surveillance still needs to be strengthened to ensure fair, transparent and well-functioning wholesale energy markets across the EU.

ACER encourages PPATs to review and improve surveillance arrangements, systems and procedures, working in particular on the quality, completeness and timeliness of suspicious transaction and order reports (STORs) submitted via ACER’s Notification platform.

ACER also found that the number and quality of STORs submitted by PPATs in 2025 increased significantly, reaching 204 reports - double the previous year’s figure. In parallel, NRAs made steady progress in screening, prioritising and closing cases.

For PPATs, ACER identified key areas in their surveillance practices where further improvements are needed:

• Strengthen functional independence and professionalisation of surveillance teams, including through appropriate training.
• Reduce reliance on basic monitoring tools in favour of more targeted ones.
• Expand surveillance coverage to potential breaches under REMIT Articles 3 and 4 (in addition to Article 5), across all markets and products.
• Enhance proactive engagement with market participants.
• Ensure timely and complete reporting of suspicious behaviour, focusing on effectiveness rather than formal compliance alone.

Read more.

For follow-ups by national regulators, ACER recommends: 

• Strengthening PPATs’ analysis of market behaviour by providing more detailed assessments of market participants’ conduct and its impact on the market.
• Further enhancing NRAs’ capacity (staff and IT resources) to manage the growing volume and complexity of cases.
• Maintaining and expanding engagement between NRAs and PPATs to further improve reporting quality.
• Ensuring timely communication with ACER to support effective coordination and case handling.

Read more.

What's next?

Don’t miss the ACER-European Commission REMIT event on 11 June. Register here.