YADENITSA PROJECT
Hydro-pumped storage in Yadenitsa – Project of Common Interest 2.21
A strategic infrastructure project for extending existing hydropower capacity and enhancing the flexibility of the energy system in Southeast Europe
The development of the Yadenitsa project represents a key infrastructure initiative aimed at expanding the existing pumped storage hydropower plant “Chaira” through the construction of a new Yadenitsa reservoir and a reversible pressure tunnel connecting it to the Chaira reservoir. The project aims to significantly increase energy storage capacity and improve the flexibility of the electricity system in this region of Southeast Europe.
PCI Status
Hydro-pumped storage in Batak is included as No. 2.21 in the second Union list of Projects of Common Interest and Projects of Mutual Interest under Commission Delegated Regulation (EU) 2026/764, published on 9 April 2026.
• PCI Refence - 2.21
• Priority Corridor - (2) North-South electricity interconnections in Central Eastern and South Eastern Europe (NSI East Electricity)
• Project Promoter - NEK EAD
The project has also been declared a national object and an object of national importance through Decision No. 707/30.08.2012 by the Council of Ministers.
Through its PCI status, the project is recognised as strategically important for the European Union.
Technical Description
• Project type - Extension of a pumped storage hydropower plant
• Main components - Construction of the Yadenitsa reservoir and a reversible pressure tunnel connecting it to the Chaira reservoir
• Increase in useful storage volume - from 4.2 million m³ to ~13.4 million m³
• Reversible pressure tunnel characteristics:
- Diameter - ~7 m
- Length - ~6,750 m
• Main facilities – intake structures, sediment shafts?, adit portal, and systems for tunnel filling and emptying
• Allocated funds from the EU – ~ €2.5 million under CEF Energy – Studies; additional funding to be announced
Regional Context
The Yadenitsa project is located within the Belmeken – Sestrimo – Chaira hydropower complex, one of the most significant energy complexes in Bulgaria. The area features mountainous terrain, abundant water resources, and well-developed energy infrastructure.
The expansion through the construction of the Yadenitsa reservoir will build upon the existing system by creating an efficient hydraulic connection between the reservoirs. This will enable optimised use of water resources in a closed cycle and enhance the efficiency of existing facilities, without significant additional environmental impact.
Added Value for Europe
The project delivers significant benefits at both national and European levels, including:
• Security of supply - Enhances the reliability of the electricity system through increased storage and balancing capacity
• Renewable integration - Improves renewable energy system integration by enabling the Chaira PSPP to operate on a weekly cycle (balancing water volumes between generation and pumping modes)
• System flexibility - Supports more efficient load management and generation balancing
• Alignment with European policy objectives - Aligned with the European Green Deal and climate neutrality objectives
Project Maturity
At the moment, the Yadenitsa project is at an advanced stage of preparation – design and permitting phase.
Key preparatory and technical documents have been completed, including:
• a positive Environmental Impact Assessment (EIA) decision (in force since 22 January 2018)
• an approved Detailed Spatial Plan (DSP) from 30 January 2019
• approvals from competent authorities
• a completed financial analysis and risk assessment
Implementation Plan
To be announced.
Environmental and Social Responsibility
The project is being developed in full compliance with the environmental legislation of the European Union and Bulgaria. An Environmental Impact Assessment has been carried out, and measures have been included to minimise impacts on ecosystems and ensure sustainable water resource management.
The project relies on existing infrastructure and a closed water cycle, significantly limiting its environmental footprint.
Public Consultations
In accordance with the TEN-E Regulation (EU) 2022/869, NEK EAD conducts public consultations and maintains active dialogue with stakeholders.
The project has undergone public consultation procedures within the EIA process, and the feedback received has been taken into account in its development. The project team will continue to ensure transparency and provide updates through official communication channels.
Regional Significance
The Yadenitsa project is of key importance for the development of the Belmeken – Sestrimo – Chaira hydropower complex and for the Bulgarian energy system as a whole. It will improve the efficiency of existing facilities while also contributing to regional economic development through job creation and stimulation of engineering and construction activities
Contact details for obtaining additional information and documents and for conveying comments and objections during public consultations:
NEK EAD
5 Veslets St.
Sofia 1000
Bulgaria
Tel:+359 2 9263 636
e-mail: nek@nek.bg
Resources:
Official Website of the European Commission
Last updates: 10.08.2026г