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In a notable shift within the energy sector, the operator of the AES Maritsa Iztok 1 coal plant is contemplating a significant upgrade: the replacement of one of its traditional boilers with a molten salt reactor. This innovative technology aims to harness excess renewable energy from the grid, converting it into thermal energy to produce steam for the plant's existing turbine. As the global landscape increasingly relies on solar and wind power, the need for a robust energy storage solution has never been more pressing, particularly to mitigate the intermittency associated with these renewable sources.

Southeastern Europe is gradually keeping pace with this trend, particularly in countries like Bulgaria, Romania, and Turkey, where investors are eager to explore alternative energy storage solutions. AES Corp's Bulgarian subsidiary is at the forefront of this evolution, seeking to implement a molten salt reactor that could significantly enhance the operational efficiency of its coal power facility in Galabovo, located in the Stara Zagora province.

The proposed molten salt reactor would function as a "Carnot battery," a system that converts electricity into thermal energy for storage, later converting it back to electricity when needed. This approach not only preserves the generator's capacity but also positions the facility to make productive use of surplus renewable energy. With a capability to store heat sufficient to run the unit at maximum capacity for five hours, the reactor could generate approximately 1.73 GWh, providing a substantial contribution to the energy grid.

Despite the technical capability of coal plants to operate continuously, many have found themselves sidelined in the evolving energy market, often running only during peak price periods. The introduction of molten salt reactors may offer a viable business model for these facilities, ensuring they remain competitive and relevant while safeguarding jobs in the sector.

The urgency for effective energy storage solutions is palpable, especially as intraday price spreads continue to widen. Market fluctuations have led to negative pricing on 2.8% of the days last year, with prices dropping below €5 per MWh for 8.8% of the time.

This is in stark contrast to projected figures for 2025, underscoring a growing disparity between supply and demand. The first half of this year has seen price differences range from €100 to €200 per MWh, with 30% of days experiencing spreads exceeding €200. Such volatility highlights the necessity for innovative solutions like molten salt reactors to address the challenges posed by the increasing variability of renewable energy sources.