After 2.5 years of downtime: Second hydro unit of Chaira Hydroelectric Power Plant is producing green energy again

After more than a month of testing, the Chaira Pumped Storage Hydroelectric Power Plant (PSHPP) is already operating in parallel with the energy system. One of the four hydro units has been switched on and the unique facility is now operating with a capacity of 130 MW.

The official launch of the hydro unit at Chaira Hydroelectric Power Plant was attended by Prime Minister Dimitar Glavchev, Energy Minister Vladimir Malinov and NEC Director Martin Georgiev. It is NEC that owns the key Chaira Hydroelectric Power Plant, which has the potential to be a kind of huge green battery, working to support our energy system.

For the first time in 2 years and 8 months, the Chaira Nuclear Power Plant is operating in parallel with the energy system, Malinov explained to journalists.

The innovative solution applied during the repair and modification of the turbine part is unique on a global scale. This became clear during the on-site visit of Prime Minister Dimitar Glavchev and Minister of Energy Vladimir Malinov.

The activities, which lasted 12 months in intensive mode, guarantee the security and efficiency of the facility, which can now actively participate in the country's electricity system. Following this success, the same approach will be used to restore hydro unit 3, with its repair expected to be completed by the end of 2025.

Meanwhile, negotiations between NEC and the original equipment manufacturer, Toshiba, regarding a medium-term solution for the repair of hydro unit 1 are at an advanced stage. They are being conducted in accordance with the Memorandum of Cooperation in the Field of Energy signed in September between Minister Malinov and the Minister of Economy, Trade and Industry of Japan, Ken Saito. According to Minister Malinov, after the final approval of the draft agreement by Toshiba, it is expected to be signed by the end of the year.

Thus, at the beginning of 2026, we will have two more hydro units available in the largest PSHPP in the region, Minister Malinov pointed out.

The repair of hydro unit 2, which is already operating, included the rehabilitation and installation of the generator stator and the turbine. After successfully passing the tests, another of the facilities is due to be put into operation in early 2025.

The repair of the second hydro unit took more than a year. Over the past month and several weeks, tests and functional tests of the facilities have been underway to ensure that the repair is successful. Currently, the facilities are operating reliably and safely, said NEC Executive Director Martin Georgiev. He specified that the stator columns in the turbine have been modified. Their shape has been changed so that the stresses inside are distributed more smoothly, and not only in certain critical areas.

The repair was mainly carried out by the Voith company, which is working on the turbine part of the plant. The test period ended on Saturday. Now the Chaira Hydroelectric Power Plant is operating in generator mode at 205 megawatts and in pumped storage at 197, due to the level of the Yadenitsa dam.

Rehabilitation of the Chaira Hydroelectric Power Plant has not been carried out since the construction of the plant and this is the first in-depth renovation of all control and management systems, as well as part of the main turbine components.

There are a number of cycles in which the hydro unit operates in pump and generator mode, which are sufficient to operate sustainably for at least 5 years at least and can certainly be replaced with the complete replacement of two of the units. However, we must be aware that this facility has been operating for many years, it has been actively operated. It has done a lot of work for the power system and will continue to do so, but of course, such types of facilities that are heavily loaded need rehabilitation or replacement depending on their condition, explained the executive director of NEC Martin Georgiev.

In response to a question, he explained that the funds for the complete rehabilitation, which began in 2019, were provided partly through the Kozloduy International Fund and partly from its own funds.

We are continuing with the next stage of the restoration of the PSHPP, which envisages the implementation of a similar solution as that of Hydro Unit 2 and Hydro Unit 3, which is already in the process of dismantling. In mid-January (2025), we will also begin dismantling the turbine part, he added, noting that everything is being done with extreme caution, caution as the main goal is to avoid any risks, both for the facilities and for people.

Martin Georgiev expressed his expectation that the work of Chaira PSHPP will reduce the pressure on electricity prices during peak hours, when electricity is most needed. According to him, the plant's operation will contribute to the security of Bulgaria's electricity system.

BGN 242 million is earmarked for the new public procurement, which is also partially provided by NEC and the Kozloduy International Fund. The hope is for funds from the budget and an extension of the bank guarantee. NEC will also take advantage of grants, if there are suitable ones.

NEC is also working on the project to build two new PSHPPs. Currently, an expansion of the feasibility study is underway for them, which is financed by the EIB and for which a consortium of European engineering companies has been selected. Currently, the project for the two new PWPPs is at the analysis stage.

Chaira PSHPP is the largest underground power plant on the Balkan Peninsula, located under the Belmeken Dam. The plant has 4 hydropower units (HPUs) with a total capacity of 864 megawatts in generator mode and 788 megawatts in pump mode. The installed capacity of the Chaira PSHPP is comparable to one unit of the Kozloduy NPP. The plant operates as a battery with a renewable resource - water and plays a key role in the security and balancing of the electricity system. We recall that, following an incident during post-rehabilitation tests, the plant has not been in operation since March 2022.

The implementation of the large-scale project to restore the Chaira PSHPP will significantly contribute to the successful integration of the growing RES production throughout the region and the implementation of decarbonization goals at the national and European levels. This is a key contribution to establishing Bulgaria as a regional leader in green energy storage.

Prime Minister Glavchev expressed his satisfaction with the successfully completed work and committed the government to continue working at full speed until the end of the year. Regarding the state budget for next year, he commented to journalists: “The initial assurances were that the budget would be adopted by the end of the year, but this did not happen. Instead, the National Assembly went on vacation without rejecting the budget, which would have allowed it to submit a new bill to extend the old one.” He was categorical that the caretaker government adheres to the laws and the Constitution and refuses to take actions that would violate them. “The main goal is to comply with current expenditures and keep the deficit to 3%,” Glavchev also said, quoted by the government’s information service. He emphasized that the expenditure part of the budget was formed on the basis of the promises of various political forces and laws adopted by previous national assemblies.

The Prime Minister recalled that an important goal is for Bulgaria to fulfill the criteria for membership in the Eurozone. “The last criterion is expected to be fulfilled by mid-January, after which reports will be submitted to the European Central Bank and the European Commission. The Prime Minister also announced that talks are underway with the European Commission for an accelerated assessment, which will allow progress in the process of our accession to the Eurozone.