Geothermal energy is the cheapest substitute for coal-fired power plants
- Nikola Sechkaryov
- Dec 17, 2025
- 4 min read
Georgi Stefanov, member of the Management Board of the Bulgarian Association Geothermal Energy (BAGE)
Bloomberg TV Bulgaria:
Geothermal energy is the cheapest, most effective, and easiest solution for replacing sources of baseload thermal energy capacity in Bulgaria, including coal-fired power plants. Unlike solar and wind energy, it is a local resource with strategic potential. This was stated by Georgi Stefanov, a climate policy expert, in the program “In Development” on Bloomberg TV Bulgaria, hosted by Georgi Mesrobovich.
Geothermal energy has an efficiency practically comparable to that of nuclear power—around 95–96%—and provides electricity, heat, and cooling, whereas coal-fired power plants can provide only electricity, and more rarely electricity and heat, Stefanov emphasized.
According to him, geothermal energy can complement and support the boom in conventional renewable energy sources—solar panels and wind power.
“No matter how much solar and wind capacity we install, it will not deliver energy 24 hours a day. That capability belongs to baseload capacities, and geothermal energy is one of them.”
“Geothermal energy can be used everywhere territorially and regionally, depending on requirements. If a large city like Sofia needs a new type of district heating, it should be based on geothermal resources, as the capital is one of the best locations for the development of this new energy source,” the guest urged.
Three times faster and twice cheaper than nuclear power plants
The deployment of geothermal energy is three times faster than the construction of a nuclear power plant and at least twice as cheap, Stefanov noted, adding that the cost of geothermal energy is comparable to that of solar power and large offshore wind farms.
“Unlike the price dynamics of other energy sources, geothermal energy has a constant cost parameter—both in terms of the final product and the price per kilowatt of installed capacity.”
The only price difference depends on how deep the heat is located underground, Stefanov explained. He dismissed claims that geothermal energy is high-risk, noting that it has been used for more than a century and that half a century ago Bulgaria had three geothermal power plants.
“Modern geothermal power plants are closed-loop systems; they do not even use groundwater, which is often corrosive. Closed systems seek heat from the rock and avoid aquifers due to their corrosive properties and associated risks,” he emphasized, adding that this is the direction of future development.
At the beginning of next year, the European Commission will present the first Strategic Action Plan for the development of geothermal energy at the European level, as it enables Europe to use its own resources and ensure the necessary energy security, Stefanov announced.
Diversification of renewables, not new units at Kozloduy NPP
Over the past year, we have witnessed unrealistic plans for the future construction of new nuclear capacities in Bulgaria at prices that the Bulgarian economy cannot afford, the guest believes. According to him, this would result in wasted funds and efforts, while it is far more economically, temporally, and socially efficient to invest in the diversification of renewable energy sources as the cheapest energy resources.
“With the funds we want to spend on Units 7 and 8 of the Kozloduy Nuclear Power Plant, Bulgaria could supply energy to the entire Balkan Peninsula if we invest in alternative energy sources through a combination of all available options—solar, wind, and geothermal energy.”
The choice, Stefanov asserted, is between paying off debt for decades or continuing to be a major energy producer and profiting from it.
Energy is no longer the sector with the highest carbon emissions
Most likely, 2025 will be the first year in which the energy sector will not be the leading economic sector in terms of carbon emissions, the guest said. Forecasts based on the amount of electricity and thermal energy produced show that emissions will fall below 10 million tonnes.
The transport sector has experienced enormous growth over the past two decades at the expense of declining emissions from the energy sector. “The discussion on reducing emissions from transport includes paid zones and car-restricted areas in the centers of large cities. We must realize that we have another problem—the elephant in the room will not be coal, but transport,” Stefanov emphasized.
Therefore, alternative solutions need to be supported, he believes. One of the key reforms under the Recovery and Resilience Plan was the adoption of a law to promote electric mobility. It was supposed to define low-carbon zones in large cities and enable municipalities to build charging infrastructure in outer neighborhoods so that people could gradually transition to these more efficient alternatives, Stefanov said.
The law was supposed to be adopted by the end of December, but this did not happen. Last month it was put up for public consultation, and over the past four years there have been three versions of it, the guest added.
Do coal-fired power plants have a future? What is the role of solar and wind energy in Bulgaria’s overall energy mix? How will modes of transport change in the future? - https://www.bloombergtv.bg/a/17-v-razvitie/153622-geotermalnata-energiya-e-nay-evtiniyat-zamestitel-na-vaglishtnite-tets
