Efficiency of hydropower plants: the renovation of part of Belmeken-Sestrimo cascade is completed

The rehabilitation of part of the Belmeken - Sestrimo - Chaira cascade was completed. The "Sestrimo" HPP was put into operation. The Chaira pumped storage hydropower plant remains to be repaired and the Yadenitsa dam to be built in order to make the cascade effective. At full load, it would produce about 60% of the state-owned National Electricity Company's electricity.

The National Electricity Company (NEC) has asked for a price increase of less than 10% for electricity from its hydro plants only because of inflation and depreciation of the facilities, the executive director explained. The company has also given a request to use electricity from the coal plants as it will remain a public supplier this year.

Martin Georgiev, executive director of NEC: "The consumption of households within one day, these days, for example, is between 650 and 1650 megawatts, so the highest value compared to the lowest is almost three times, so we have to have the tools to provide this energy."

The National Electricity Company owns 28 water power plants and 3 pumped storage hydropower plants. However, half of the company's energy is generated by the Belmeken-Sestrimo-Chaira cascade. Once the rehabilitation is completed, half of the capacity will be operational.

Petar Dimitrov, caretaker Minister of Environment and Water: "This successful rehabilitation will allow the efficient operation of these facilities for the next 15 years, which will guarantee our energy security."

The rehabilitation of the cascade, which was built in 1973, took nearly six years and cost €39 million. What remains is to commission the Chaira pumped storage hydropower plant. The cascade includes two pumped storage hydropower plants and two hydropower plants. Its purpose is to balance the other capacities in the country such as Kozloduy NPP and the TPPs. The advantage of hydroelectric power plants is that they can be started up and shut down in a short period of time. The largest pumped storage hydropower plant in the country is Chaira, which failed two years ago. It still remains offline.

It will take at least three years to repair the pumped storage hydropower plant. The reasons for the breakdown are not yet clear, but it is known that repairing it would cost at least one hundred million BGN. A group from one of the largest Swiss companies in the sector visited last week.

Martin Georgiev, NEC's executive director: "They also said what we have said many times, that they were very surprised by this breakdown, that it was atypical and jokingly said they wished they would never have to repair such a breakdown."

The most likely cause of the breakdown, after numerous inspections, turned out to be improper operation of the facility. Specialists from the Japanese company Toshiba are currently visiting Chaira to once again analyse how to repair the facilities.

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Martin Georgiev, Executive Director of NEC: "So far we have no news of concern and no feedback from the contractor."

NEC is also about to announce a tender for the supply of the first battery for the hydropower plant, which will make the plant more efficient. The electricity from it will be possible to be stored at generation and used at the right time.