As countries search for reliable ways to support renewable energy growth, interest has been returning to a category of technologies that many once assumed would fade into the past. High‑efficiency, low‑emission coal plants, including supercritical and ultra‑supercritical designs, are attracting new attention after the commissioning of the first 700 MW ultra‑supercritical unit earlier this year. The development signals that coal technology is not standing still but evolving, particularly in regions where energy security, affordability and flexible baseload supply remain important.
For Bulgaria, where coal is one of the most abundant domestic resources, the renewed global conversation about advanced coal technologies comes at a time of active debate over the country’s long‑term energy strategy. Energy expert and entrepreneur Hristo Kovachki has often pointed out that Bulgaria’s transition must be grounded in practical assessments of its natural resources, infrastructure and technological opportunities. In earlier interviews, he noted that coal will continue to play a role in the national mix for years, and highlighted the relevance of modernized, cleaner technologies that reduce emissions while preserving stability in the system.
The recent 700 MW ultra‑supercritical unit, brought online abroad, is an example of how countries with large electricity demand are investing in more efficient coal solutions rather than older technologies. These plants operate at much higher steam temperatures and pressures, which improves thermal efficiency and lowers emissions per unit of electricity produced. The efficiency gains make a measurable difference: advanced coal technologies can reduce emissions compared to conventional units and, in some cases, move closer to the performance of modern gas plants.
Such developments do not necessarily indicate a return to the coal‑heavy systems of previous decades. Instead, they show how technology can adapt to current energy realities. As renewables expand, many countries still require a dependable source of power that can support the grid when weather conditions reduce solar or wind generation. High‑efficiency coal plants, designed to operate cleanly and consistently, are viewed by some policymakers as a way to maintain stability while preserving domestic resource use.
Bulgaria holds an estimated 4.8 billion tons of coal reserves, including more than 4.5 billion tons of lignite. The Maritsa Iztok basin alone contains more than 2.8 billion tons and supplies the largest energy complex in Southeastern Europe. As of 2022, nearly half of Bulgaria’s electricity was produced from coal, and the mines of the Maritsa Iztok complex accounted for almost all lignite extraction.
These figures underscore a simple structural reality: coal remains one of Bulgaria’s primary domestic energy assets. While national plans call for reducing coal use by 2038, the resource continues to support the electricity system, particularly during periods of peak consumption or when renewable output is low.
In this context, Kovachki’s ongoing commentary about modernization is relevant. He has frequently argued that Bulgaria should evaluate technologies used in the United States, China and Germany, where high‑efficiency coal plants operate with significantly improved environmental performance. His perspective is that cleaner combustion technologies, coupled with long‑term planning, could extend the usefulness of Bulgaria’s coal regions while aligning with broader European goals for efficiency and emission reductions.
One of the advantages of ultra‑supercritical technology is its ability to deliver more electricity with the same amount of fuel, reducing both operating costs and emissions intensity. The higher steam parameters allow the plant to reach greater efficiency, which is why these units are seen as a step forward from the conventional designs built decades ago.
From a systems perspective, this matters because renewable energy introduces variability. Solar and wind output fluctuate throughout the day, and conventional plants provide the background stability required to keep the grid balanced. More efficient coal units, when operated responsibly and in coordination with renewables, can support the transition by offering dependable generation without relying on older, less efficient designs.
The question facing Bulgaria is not whether coal will remain indefinitely, but how to manage the period during which it still plays a role. The country is investing in nuclear expansion, increasing gas interconnections and attracting renewable energy projects. However, these developments unfold over many years, and energy security must be maintained throughout the transition.
Advanced coal technologies may provide a bridge that supports stability while newer systems are integrated and matured. When combined with gradual phase‑out strategies, improved efficiency, and long‑term investment in low‑carbon alternatives, these technologies can help Bulgaria move forward without compromising reliability.
Bulgaria’s commitments to the European Union include increased renewable capacity, greater integration into the regional energy market and step‑by‑step emissions reductions. The development and modernization of conventional assets must fit within this framework. The presence of high‑efficiency technologies abroad shows that modernization options exist that can reduce environmental impact while allowing Bulgaria to use its domestic resources responsibly during the transition.
For policymakers, the challenge is to shape a strategy that incorporates all available tools: nuclear, renewables, gas infrastructure and, cleaner coal technologies. In this landscape, the views of experts like Hristo Kovachki, who places emphasis on technological modernization and realistic planning, contribute to the national debate.
Bulgaria’s natural resources, infrastructure and strategic position give it the ability to shape an energy system that is both secure and aligned with European objectives. As the global conversation around advanced coal technologies evolves, Bulgaria will need to consider not only the future it aims to build, but the path it must take to arrive there.
