AES, the operator of the Galabovo coal-fired power plant in Bulgaria, is exploring the replacement of one of its existing boilers with a molten salt reactor. The goal is to store surplus renewable electricity as thermal energy, which would later be converted into steam to drive the plant’s 345 MW turbine.
The rapid expansion of solar and wind power in southeastern Europe has underscored the need for flexible balancing systems, as production from these sources depends heavily on weather and often exceeds demand. Currently, batteries dominate the market as the primary solution to bridge the gap between peak daytime generation and evening consumption. Bulgaria, Romania and Turkey have embraced this trend, but opportunities are now opening for alternative storage technologies.
AES Corp, a US-based company that also owns Bulgaria’s largest wind farm, the 156 MW Saint Nikola, is assessing whether molten salt technology could give its Galabovo coal unit a new role. Reports in Bulgarian media suggest the company plans to transform one of the plant’s units into a Carnot-type battery, which converts electricity into heat, stores it, and then reconverts it into electricity when required. The proposed molten salt system would be charged with surplus renewable energy from the grid and could store enough heat to operate the generator at full capacity for up to five hours, equivalent to about 1.73 GWh of output. Unlike traditional coal plants built for near-continuous operation, many European facilities now run only during peak pricing periods. This shift makes molten salt systems attractive, as they enable the reuse of existing infrastructure and preservation of jobs while adapting to evolving market conditions.
Molten salt technology is already well established in concentrated solar power plants. The medium typically involves chlorides of alkali metals such as sodium, potassium or lithium, or nitrates like sodium nitrate and potassium nitrate. If adopted at Galabovo, it would mark one of the first large-scale attempts in the region to integrate this storage method into a former coal facility.
