How does the shift impact coal-fired power plants in Bulgaria?
Coal plant utilization rates are falling.

In Bulgaria, coal-fired power plants are facing a steady decline in both utilization and importance. Their share in the electricity mix, which was once above 40% (mid-2010s through 2021), has now dropped to around 27% (2024/2025). These plants used to run at very high capacity factors of over 70%, meaning they operated close to full load most of the time. Today, they are dispatched for fewer hours as solar and wind increasingly cover daytime demand.

This reduced operating time creates growing economic stress. Plants built and financed under assumptions of continuous operation now struggle to remain profitable. To maintain jobs and preserve a sense of system security, the Bulgarian government has supported them through subsidies and capacity payments, but this approach is under mounting pressure. The EU Emissions Trading System (ETS) has made coal generation progressively more expensive, pushing it out of the merit order compared to cheaper renewables.

Despite these changes, the system has remained stable and reliable. The Bulgarian Resource Adequacy Assessment (BGRAA) 2023, published in January 2024, explicitly modeled scenarios with reduced coal generation to test whether the grid could still meet demand. The results showed that even with coal output declining well below historic levels, Bulgaria maintains sufficient capacity margins to ensure reliability. Loss of Load Expectation (LOLE) indicators remained close to zero under baseline assumptions, and even in high-risk scenarios the expected shortfalls were limited to only a few hours per year — well within European adequacy standards.

The assessment highlighted that flexible resources such as pumped storage at Chaira, hydro cascades, growing battery capacity, and strong interconnections with Greece and Romania are already compensating for declining coal. This confirms that reliability in Bulgaria no longer depends solely on baseload lignite plants, but rather on a diverse mix of renewables, flexibility, and cross-border balancing.