Every two years, the European Network of Transmission System Operators for Electricity (ENTSO-E) adopts a non-binding Union-wide ten-year network developme​​nt plan ​(TYNDP), including a European generation adequacy outlook.

The TYNDP plays a central role in the development of electricity transmission infrastructure in Europe, which is needed for achieving the European policy goals.

The main objectives of the TYNDP are:

• to identify investment gaps, including cross border capacities

• to contribute to a sufficient level of cross-border interconnection and non-discrimination, effective competition and the efficient functioning of the market

• to ensure a greater transparency of the European electricity transmission network.

The TYNDP prepared by ENTSO-E builds on national investment plans prepared by the transmission system operators (TSOs) and takes into account the regional investment plans, published every two years.​

ACER is responsible for:

• Providing an opinion on the contribution of the TYNDP to ENTSO-E, the European Parliament, Council and Commission, whenever ACER considers this draft is not contributing to the market's transparency and effective competition.

• Assessing the consistency between the European TYNDP and the national plans. If inconsistencies are found, ACER recommends amending the national plan or the TYND.

• Monitoring the implementation of the TYNDP, after its positive evaluation. If ACER identifies inconsistencies, it investigates the reasons and makes recommendations to TSOs, NRAs and other competent bodies, in order to contribute to the investments' implementation.

In its latest Opi​nions (April 2023), ACER acknowledges the difficulties arising from the TYNDP process and welcomes a number of improvements in the draft 2022 electricity TYNDP.

However, significant steps forward are still needed, and for this purpose ACER recommends ENTSO-E to:

• Make all relevant inputs accessible in a clear and straightforward format as part of the 2022 final electricity TYNDP publication.
• Provide transparency on how the investment costs for the needs identification were derived by distinguishing between internal reinforcements and overall project costs.
• Publish for each cross-zonal boundary and each flow direction the transfer capacities of the current grid, starting grid (for the purpose of needs identification) and of the reference grid for 2030 and for 2040.
• Use the 10,000 EUR/MWh Value of Lost Load (VoLL) where no specific data is available.
• Explain how an assessment of resilience, if any, was carried out in the 2022 final electricity TYNDP (potentially including improvements for future TYNDPs).
• Review and eliminate the project-specific inconsistencies reported in ACER Opinion on electricity projects and consider the differences identified by national regulators between the NDPs and the 2022 draft electricity TYNDP.

Also, specific recommendations to ENTSO-E on a substantial improvement of future TYNDPs are provided, inter alia:

• Restructure the TYNDP development process in order to complete it by December of the TYNDP year (considering also ACER’s opinion).
• Conduct a substantial consultation of the important methodological elements and parameters considered in the various deliverables of the TYNDP early enough in the process to have the capability to consider stakeholders’ comments.
• Calculate the benefits of projects according to all the joint scenarios developed by ENTSOs, and for all relevant time horizons to ensure adequate consideration of uncertainty.
• Base the modelling of the grid on an appropriate starting grid (for the needs exercise) and reference grids (for the CBA assessments) by including only the projects which strictly comply with the rules set in the respective implementation guidelines.
• Calculate the additional transfer capabilities of each project (and not leave this task to the promoters themselves), perform the calculations with more granularity (e.g. calculate at least seasonal NTCs) and improve their transparency.
• Consider the impact of the 70% interconnection capacity availability targets where relevant in the modelling of the power system for the development of the TYNDP.
• Enhance the consistency between the NDPs and the EU TYNDP by implementing the measures recommended in the ACER Opinion on electricity projects.

​​​​​Network development scenarios represent visions of the future, according to which the assessment of projects’ benefits is made using the CBA. The TEN-E Regulation defines which variables should comprise scenarios for electricity and gas. The European Network of Transmission System Operators (ENTSOs) are responsible for developing common network development scenarios for gas and electricity. 

Under the TEN-E Regulation, ACER is responsible for creating Framework Guidelines for Scenario Development, while ENTSOG and ENTSO-E (the ‘ENTSOs’) are tasked with developing network scenarios based on these guidelines. In January 2023, ACER published its Framework Guidelines, aiming to establish a transparent, inclusive, and robust process.

In its latest Opinion (October 2024), ACER welcomed some improvements in the scenarios’ development process, ACER’s assessment identifies several areas of non-compliance with its Framework Guidelines:

• Diverging scenarios: rather than developing different scenario variants based on economic factors, the ENTSOs created diverging scenarios, leading to less reliable results.
• Delayed process: scenarios’ development was delayed, negatively impacting other processes.
• Slower stakeholder group formation: the process of establishing the Stakeholder Reference Group took longer than expected, which impacted the stakeholder engagement’s overall effectiveness.
• Transparency: despite enhanced transparency and stakeholder consultations, the draft 2024 Scenarios Report still did not fully meet the transparency standards set by the Framework Guidelines.

ACER expects some of these issues to be addressed in the final 2024 Scenarios Report for the TYNDP and anticipates that ENTSOG and ENTSO-E will further tackle the remaining shortcomings in the 2026 scenarios.

When developing new networks, setting up an appropriate and transparent cost estimation is essential. Using reference values of specific costs can facilitate many processes, increase their credibility, and enable reliable comparisons at European level.

Under the TEN-E Regulation (Article 11(9)), ACER is required to establish and publish a set of indicators and corresponding reference values every three years for the comparison of unit investment costs (UICs) for comparable projects of the energy infrastructure categories listed in Annex II.

ACER published the first set of UIC indicators for the categories outlined in points (1), (2), and (3) of Annex II in April 2023. These indicators and their reference values can be used for various planning and evaluation processes, including:

• supporting the European Network of Transmission System Operators for Electricity (ENTSO-E) and Gas (ENTSOG) in the cost-benefit analyses carried out for their Union-wide ten-year network development plans (TYNDPs);
• assessing and selecting projects of common and mutual interest (PCIs/PMIs);
• informing cross-border cost allocation (CBCA) decisions.

UICs indicators were specifically established for the electricity infrastructure category and related assets, based on data provided by project promoters. The indicators provide values for the average, median, first and third quartiles of UICs.

Would you like to know more?

Take a look at our report on European energy infrastructure UICs and watch the recording of our workshop on the topic. 

According to revised TEN-E Regulation, ACER is required to publish the first UIC indicators for energy infrastructure categories related to large electrolyser facilities and carbon dioxide by 24 April 2025. However, since no relevant projects have been commissioned under these categories in recent years, there is currently insufficient data to establish robust indicators by this deadline.

For this reason, ACER has decided to delay data collection until relevant projects are commissioned. In the meantime, ACER will:

• continue to closely monitor developments in these project categories;
• begin the next UIC data collection cycle at the end of 2025. If suitable projects are available by that time, ACER will publish the corresponding indicators and reference values by April 2026.

The Regulation on guidelines for trans-European energy infrastructure ('TEN-E Regulation') foresees the development of a harmonised EU-wide methodology for cost benefit analysis (CBA) of projects included in the future Ten Year Network Development Plans (TYNDP), and for selecting the Projects of Common Interest (PCIs) and Projects of Mutual Interest (PMIs) at European level. 

The Regulation also foresees the use of this methodology for deciding on the cost allocation of cross-border infrastructure projects (CBCA). The CBA methodology is developed and improved over time by ENTSO-E and is approved by the European Commission. ​

Whenever an updated CBA methodology is proposed by ENTSO-E, ACER provides an opinion on it to ENTSO-E. ​

In its latest Opinion, ACER notes improvements, which include:

• the assessment of hybrid offshore projects (i.e. grid projects that serve a dual purpose, to connect offshore generation and interconnect two bidding zones);
• the definition of the reference grid; and
• the assessment of projects’ commissioning dates and the commissioning year of projects involving multiple investments.  

However, important shortcomings are also identified, such as the need to extend the analysis of security of supply by considering future extreme weather events, to simplify the assessment of hybrid offshore projects, to foresee the identification of beneficiaries and cost bearers at national level, and the lack of concrete methodologies for the assessment of ancillary services’ benefits.

ACER urges ENTSO-E to adapt the draft CBA Guideline in line with the considerations included in its Opinion before submitting it to the European Commission for approval. ​​

Developing new networks in Europe in order to facilitate cross-border flows requires a close coordination of several processes and actors.

A common EU-wide Cost-Benefit Analysis methodology was developed by ENTSO-E to be used for infrastructure projects assessment, and it is reviewed when needed. 

Every two years, based on the scenarios on the future state of the electrical system, ENTSO-E assesses the projects included in the EU-wide Ten-Year Network Development Plan (TYNDP). ​

ACER is strongly involved in all network development aspects, assessing not only the methodologies and guidelines developed by ENTSO-E for the various elements of the TYNDP, but also how they are implemented for the project assessments in the TYNDP. The Agency also verifies the consistency of the TYNDP with national development plans and provides an overview of related infrastructure reference costs. ​

Significant enhancement in electricity grid capacity is needed to realise Europe’s decarbonisation objectives and ensure a high level of security of supply. New grid build-out is just one way and proving to be the costliest way to do it. Despite their advantages, innovative solutions are not yet spearheading investment choices.

In the context of the European Commission’s EU Action Plan for Grids, ACER is looking at best practices to promote smart grids and network efficiency technologies through tariff design. 

ACER has thus commissioned the Florence School of Regulation (FSR) to conduct a study on existing regulatory frameworks and how regulators could incentivise a more efficient use of existing and future electricity grids.

Building on the previous research conducted by FSR on behalf of ACER, the report presents a new regulatory scheme which focuses on the value projects bring (i.e. benefit) and not on their costs. By sharing this benefit between the grid user and grid operator, a stronger incentive for technology-neutral solutions is created while mitigating the tariff increase (in comparison to the business as usual, e.g. investing into infrastructure alone).

Maximising cross-zonal trading opportunities is a core element to ensure an efficient internal electricity market. It is also important for meeting a number of future challenges in Europe's energy trajectory, including the decarbonisation targets.

The Clean Energy Package offers a new opportunity to increase the capacity offered for cross-zonal trade. In particular, Transmission System Operators are required to ensure that at least 70% of the transmission capacity is offered for cross-zonal trade, while respecting operational security limits. ​

For more information about the 70% minimum target, read our dedicated Q&A. 

The minimum 70% target has become a key element of market integration, which requires intensive monitoring. To ensure a harmonised approach on how to monitor the achievement of the minimum level of available cross-zonal capacity (MACZT), ACER is monitoring the MACZT in relation to the 70% target.

The results are published yearly in dedicated reports. 

Electricity transmission networks, once developed purely for national requirements, have become increasingly interconnected across Europe, creating one of the largest electricity transmission systems in the world. The system enables the operation of the Internal Energy Market (IEM), requiring coordinated actions of all Member States in terms of its development and operation.

To facilitate the integration of the IEM, individual Transmission System Operators (TSOs) cooperate under the umbrella of the European Network of Transmission System Operators for electricity (ENTSO-E) when developing new infrastructure assets. ​

ACER plays a crucial role in overseeing all aspects of network development by:

• Reviewing the​ draft Union–wide Ten-year Network Development Plan prepared by ENTSO-E every two years, assessing its consistency with the national Ten-year Network Development Plans, and monitoring its implementation

• Coordinating National Regulatory Authorities' work on establishing and making publicly available a set of indicators and reference values of unit investment costs of infrastructure projects

• Supporting the selection of priority projects in Europe, by providing its views on the biennial draft regional lists of Projects of Common Interest, and by monitoring annually their implementation

• Monitoring the implementation of the Inter-TSO compensation mechanism

• Deciding on some cross-border issues, such as the allocation of the investment costs of projects of common interest or on granting exemptions from third party access in case NRAs fail to agree

• Striving towards efficient and cost reflective network tariffs, by reviewing the appropriateness of transmission charges to be paid by generators and identifying best practices of transmission and distribution tariff methodologies

• Ensuring the efficient use of congestion revenues, by approving the methodology proposed by all TSOs

• Providing views on ENTSO-E's work planning and Innovation activities​

Thank you for your interest in the EU Agency for the Cooperation of Energy Regulators (ACER). 

While the Agency is committed to attending externa​l events related to its field of work and competences, it is obliged, due to the limited resources at its disposal, carefully to select the events in which its staff members participate. 

A decision is taken based on the event in question, as well as on the availability of staff members on the date(s) of the event.

​In order for us to make an informed decision about the event at which you would like an ACER staff member to speak, we kindly ask you to send us a request with details about your event to press(at)acer.europa.eu.

​​​​​​​​​​​​​​​The Network Code Implementation and Monitoring Group (NC IMG) was a forum for high level strategic coordination between the European Commission, the European Union Agen​cy for the Cooperation of Energy Regulators (ACER), the European Network of Transmission System Operators for Electricity (ENTSO-E), and the European Network of Transmission System Operators for Gas (ENTSOG).    

The NC IMG used to oversee the implementation and implementation monitoring of electricity ne​twork codes and gas network codes in the EU. Network codes and guidelines are rules to harmonise technical, operational and market rules governing the EU's electricity grids and gas networks, making an integrated EU internal energy market possible.    ​​​​​

The NC IMG is no longer operational and its work has been discontinued in 2020.

​The Gas Networ​k Codes Functionality Platform (FUNC) is managed by ACER and ENTSOG with the support of the European Commission. The platform allows stakeholders to report cross-border, regional and European issues related to the implementation of gas network codes and guidelines. This cooperation facilitates ACER and ENTSOG to find solutions to the cross-border, regional and European issues identified.    

ACER and ENTSO-E co-organise three European Stakeholder Committ​ees (ESCs), one for each family of electricity codes (market codes, operational codes, and connection codes). 

They complement, rather than replacing, the​ legal obligations to consult and inform stakeholders during the implementation of electricity network codes. ​​​​​​

Stakeholders' database tracking all queries about electricity network codes​