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The visit was part of a program to share best practices and experience in the field of hydropower

On May 22, NEK hosted representatives from Axpo's Hydropower Division as part of a knowledge-sharing programme. Axpo, Switzerland's leading renewable energy producer, operates 4,330 MW of hydropower and pump storage plants and is an international leader in energy trading and marketing of solar and wind energy.

The Axpo delegation comprised Jörg Huwyler, Head of Division Hydro & Biomass; Daniel Loosli, Leading Engineer Hydro & Biomass; Emil Bieri, Head of Digital Transformation from Axpo Hydropower Division; and Milena Videnova, Executive Director of Axpo Bulgaria. The Bulgarian delegation was headed by NEK’s CEO Martin Georgiev.

The experts toured the fully refurbished Belmeken Pumped Storage Hydropower Plant (PSHPP) and Momina Klisura Hydropower Plant (HPP), Belmeken Dam, and received an update on the Chaira PSHPP restoration project.

This visit builds upon a previous collaboration that began with an official NEK delegation visiting Axpo's headquarters in Switzerland in September 2023. There, Bulgarian specialists familiarised themselves with the construction and operation of the Limmern PSHPP, which shares similar characteristics to the Chaira PSHPP. Sharing expertise and best practices in hydropower technology and management can contribute to more efficient and sustainable energy production, as well as support the modernisation and efficient operation of both companies' hydropower facilities.

„Cooperation with Axpo plays an important role, as both companies are committed to promoting renewable energy sources and contributing to the transition towards a greener energy future. Knowledge exchange provides a strong foundation for implementing cutting-edge technology and effective operational strategies, ensuring continuous improvement and innovation in the hydropower sector.”, Martin Georgiev commented

About Axpo

Axpo is driven by a single purpose – to enable a sustainable future through innovative energy solutions. Axpo is Switzerland's largest producer of renewable energy and an international leader in energy trading and the marketing of solar and wind power. Axpo combines the experience and expertise of more than 6,700 employees who are driven by a passion for innovation, collaboration and impactful change. Using cutting-edge technologies, Axpo innovates to meet the evolving needs of its customers in over 30 countries across Europe, North America and Asia.

About NEK

NEK EAD is the biggest producer of electricity from renewable sources in Bulgaria

The Company lies at the heart of the electric power system of Bulgaria, producing electricity at 31 hydro-power and pumped storage hydro-power plants, with a total installed generating capacity of 2739 MW and pumping capacity of 932 MW. The flexible generation facilities of the company have a key role in ensuring security of supply and reliability and security of the grid system of Bulgaria. With its hydroelectric power the company contributes to the country’s renewable targets in the total energy balance.

NEK operates some of the largest dams and hydropower schemes in the country, applying stringent requirements on their O&M safety and efficiency. The total capacity of the dam reservoirs operated by NEK EAD represents 55% of the total controlled water resources in the Republic of Bulgaria.

NEK successfully completed the rehabilitation of Belmeken-Sestrimo-Momina Klisura, the largest hydropower cascade in Bulgaria

With the completion of the modernization of Sestrimo hydropower plant, the entire cascade, 735 MW in generating mode and 104 MW in pumping mode, is available for renewable energy production

With the modernization of Sestrimo hydropower plant NEK successfully completed the rehabilitation of the largest hydropower cascade in Bulgaria, Belmeken-Sestrimo-Momina Klisura. The event was celebrated with the participation of the Minister of Environment and Water, Eng. Petar Dimitrov, Deputy Minister of Energy, Mr. Georgi Samandov, Chairman of the Board of Directors of BEH, prof. Vesselina Kanatova-Buchkova, representatives of EBRD, Deputy Ambassador of the Czech Republic, Mr. Petr Vavra, Rector of the Technical University of Sofia, prof. Ivan Kralov, the Chairman of the BBCPE, prof. Valentin Kolev, representatives of the rehabilitation contractor consortium, representatives of the local government, veterans and employees of the company.

The successful implementation of the rehabilitation of both Sestrimo HPP and the power plants of the whole cascade is of key importance for ensuring the stability and reliability of the Bulgarian power system. “The modernization ensures failure-free operation of the plants, which will continue to be a reliable source of renewable energy for decades to come," emphasized NEK CEO Eng. Martin Georgiev.

Eng. Georgiev thanked the donors of the project and especially the European Commission and the KIDS Fund Administrator, EBRD, for their support throughout the project implementation. He also thanked the rehabilitation contractor for the successful cooperation. Martin Georgiev also expressed his appreciation to the employees of Sestrimo HPP and congratulated them for their high professionalism and excellent performance of the modernization.

"The flexibility of the hydropower capacities allows successful balancing of the electricity system not only in Bulgaria but also in the region, which makes Belmeken-Sestrimo-Momina Klisura cascade a key component for the Bulgarian energy sector," Deputy Energy Minister, Georgi Samandov, said.

Minister Dimitrov wished a trouble-free operation and assured the hosts from the Ministry of Energy and NEK that in the face of the MoEW, as directly involved in water management at national level, they have a reliable partner who will always contribute to the common strategic goals.

The scope of the rehabilitation of Sestrimo HPP includes design, manufacture, supply, installation and commissioning of turbine equipment, plant-wide control and monitoring systems and new operator stations. The modernization will contribute to reducing maintenance costs, improving performance in terms of voltage levels and frequency control, increasing operational reliability, and making more efficient use of the available hydropotential.

The cost of the rehabilitation of Sestrimo HPP is EUR 4,401,131.55 and the cost of the entire cascade is EUR 19,997,642.45. The financing is 70% European funds from the Kozloduy International Decommissioning Support Fund (KIDSF) and 30% NEK's own funds. KIDSF is administered by the EBRD and funded by the European Union and the following donors: Austria, Belgium, Denmark, France, Greece, Ireland, the Netherlands, Spain, Switzerland and the United Kingdom.

Further information about the rehabilitation

The Sestrimo HPP rehabilitation project was implemented within the framework of a grant agreement with the European Bank for Reconstruction and Development as KIDSF Administrator for the rehabilitation of Belmeken-Sestrimo-Chaira hydropower complex and the rehabilitation of Vacha-1 HPP 110 kV switchyard and other HPP systems under joint control. The total budget of the agreement is EUR 37 million, of which 70% is financed by KIDSF and 30% by NEK.

Belmeken - Sestrimo - Momina Klisura cascade includes Belmeken PSHPP, Sestrimo HPP, Momina Klisura HPP, Belmeken Reservoir, Stankovi Baraki balancing basin and Momina Klisura balancing basin. It is on the northeastern slopes of the Rila Mountains and extends from 1920 m above sea level at Belmeken dam to 369 m above sea level at Momina Klisura HPP.

On 18.05.2018 a contract was signed between NEK EAD and consortium KONČAR KET - ČKD BLANSKO - RUDIS for the rehabilitation of the three power plants of the cascade.