Photo: ContourGlobal
A standalone battery energy storage system of 202 MW and 500 MWh is fully operational and actively participating in Bulgaria’s day-ahead and intraday electricity markets. ContourGlobal built it at its Maritsa East 3 coal plant, using the grid connection of one of its former units. Acting Minister of Energy Zhecho Stankov, who attended the inauguration, said the country added 5 GWh last year and estimated that the overall BESS capacity would hit 15 GWh by mid-2026.
Bulgaria is, with the Czech Republic, Poland and Germany, in the group of only European Union member states in which more than a fifth of electricity is still generated from coal. But the situation is rapidly changing. One of the biggest standalone battery storage installations in Eastern Europe and among the first in Bulgaria recently came online. Located within the ContourGlobal Maritsa East 3 (Maritsa iztok 3) coal power plant, the facility uses the grid connection of a former unit.
Two remained in operation, supplying electricity during periods of peak demand.
The BESS has 202 MW in operating power and a duration of 2.5 hours, translating to 500 MWh, the company said. It inaugurated the battery system in the presence of Acting Minister of Energy Zhecho Stankov.
Stankov: New BESS creates sustainable pathway for evolution of Maritsa East coal complex
The new facility is actively participating in both the day-ahead and intraday national electricity markets, supporting optimized power dispatch and improved balancing of electricity supply and demand, the update adds.
Such projects signify how innovation and existing industrial infrastructure can work together to strengthen grid stability, improve flexibility, and accelerate the integration of renewable energy sources, Stankov stressed. The investment enhances energy security, supports market-based operation, and creates a sustainable pathway for the evolution of traditional energy hubs such as Maritsa East, in his words.
According to the acting minister, Bulgaria added 5 GWh of BESS capacity last year, nearly matching the Chaira pumped storage hydropower plant. He recalled that the overall level is set to reach 15 GWh by mid-2026.
Project materialized in under nine months
The project in Maritsa East 3 received just under EUR 30 million in support through the European Union’s Recovery and Resilience Facility (RRF) and the Bulgarian National Recovery and Resilience Plan (NRRP). The company participated with EUR 44.7 million.
Spanning 2.5 hectares, the installation is part of ContourGlobal’s 3 GWh operational BESS portfolio. The company is owned by KKR.
BYD supplied the 110 battery skids for the battery system, which also includes 28 power conversion system (PCS) and transformer units. ContourGlobal progressed from the final investment decision (FID) to commercial operation date (COD) in less than nine months.
The company is developing a second BESS on the same site, with a matching capability. It has a project for a battery in combination with a solar power plant as well.
Battery energy systems allow for the storage of electricity generated from various sources, including photovoltaic and wind power plants, during periods of low demand and its release back to the grid during peak demand, which helps balance production and consumption and the stable operation of the electricity transmission system.
Coal plants switching to energy storage
AES Corp. is interested in replacing one of the boilers in its AES Maritsa East 1 (AES Maritsa iztok 1) coal plant with a molten salt reactor.
Greece’s government-controlled Public Power Corp. (PPC Group) is already building BESS facilities at its coal plants.
German utility Uniper expressed the intention in 2024 of building a battery energy storage system, at the site of its now closed Heyden coal power plant in western Germany, with Slovenia-based energy solutions provider NGEN.
Three months ago, International Power Supply (IPS) opened its Factory X1, with a capacity of 3 GWh per year. It is the first gigafactory in Bulgaria for battery energy storage systems. The same company is building another manufacturing facility.
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