The pilot geothermal power plant project is based on the use of a completely new method of electricity production using a geothermal gravity heat pipe (Slovenian patent SI 26426 A). The unique aspect of using a geothermal gravity heat pipe is in its closed circuit, requiring only one dry well for operation. An existing but non-productive well Pg-8 in the settlement of Čentiba in Lendava is being utilized.

Dravske Elektrarne Maribor, the largest producer of electricity from renewable sources within the HSE Group, began underground work at the end of 2022 to restore the non-productive Pg-8 well, well of three thousand meters deep, Aboveground work, including construction and electro-mechanical installations, started in April 2023.

Recently, we produced the first kWh of electricity; however, consistent operation in the future will require modifications to the turbine part of the equipment, as tests have shown that the power plant currently cannot operate continuously with the thermal output of the Pg-8 well. Future steps are therefore focused on finding solutions that will enable more consistent turbine operation under given conditions, as directed by the initial results of the pilot innovative project.

Mag. Damjan Seme, General Director of Dravske Elektrarne Maribor, said: “Despite some challenges we face with the pilot geothermal power plant project, I am proud that Dravske Elektrarne Maribor, together with partners, is pioneering the field of deep geothermal utilization. We have brought the project to the point where the first kilowatt-hours of electricity have been produced. I believe that by modifying the turbine equipment, we will achieve a state that allows for consistent operation and production, paving the way for future similar projects. I am pleased that our neighbors are also interested in the project, and today we exchanged views and opinions, opening the door to cooperation in the field of deep geothermal energy utilization for electricity production.”

Hungary has been among the top five countries in Europe in the direct utilization of geothermal energy for many years. Since the beginning of the last decade, the extraction of geothermal energy has increased more than fourfold, but we still see plenty of opportunities to enhance its utilization, building on our favourable conditions – emphasized Csaba Lantos. The Hungarian Minister of Energy explained, “In order to further progress, we have prepared the National Geothermal Strategy, which is currently being finalized. According to the guiding document, we plan to double energy usage by 2030. The new applications could replace 1-1.2 billion cubic meters of natural gas by 2035. The planned measures and developments could make geothermal energy a leading sector in the Hungarian green economy. We strive to follow the best international practices in energy investments planning, and the current visit to Slovenia is about mutually beneficial exchange of experiences.”

According to the initial plans, the startup tests were scheduled for early autumn. However, the reconstruction of the Pg-8 well was prolonged as we encountered problems at a depth of 1,600 meters with the removal of the separating part (the so-called packer). Further delays were also caused by the need to remove water from the well (during the cleaning and leak testing process, the well was filled with water), as it must be dry to add the working fluid required for operation. Currently, there are still approximately ten cubic meters of water in the borehole, which is being removed through evaporation. This process is lengthy but completely environmentally friendly. Due to the extended time required for this procedure, the planned startup tests have been postponed to the winter months, about which we will inform the media and the public.

This visit was organized as part of the excursion of the summer school on “Advancements in the Development of Geothermal Energy Utilization for Heating, Cooling, and Electricity Production,” which took place from July 3 to 8, 2023. It was jointly organized by the Geological Survey of Slovenia and the Faculty of Natural Sciences and Engineering at the University of Ljubljana, with support from the Icelandic School of Energy in Reykjavik and co-financing from the EEA project INFO-GEOTHERMAL and the COST project Geothermal-DHC. The event hosted ten lecturers from seven countries and 24 participants from 13 countries in Africa, Europe, and North America. The attendees were introduced with the development of new geothermal projects, best practices in research, innovative geothermal energy utilization technologies, and optimization of operations and resource management to minimize the impact on the environment and human beings in a sustainable manner.

Pilot geothermal power plant in Čentiba in Municipality of Lendava will utilize the geothermal energy potential of the existing non-productive well Pg-8, around three thousand meters long. The fluid (ammonia) circulates in a completely closed system, which disable any contacts with the surrounding rocks. Well Pg-8 is steel cased and cemented, and as such completely sealed. Pilot geothermal power plant at the Pg-8 well will consist of an underground part, i.e. of the geothermal gravity heat pipe and the above-ground part, i.e. cooling system and turbine micro system.

The underground works include the removal of the existing pipes, for which a special equipment has been mobilized. Activities that will follow are: well gas-sealing check, geothermal gravity heat pipe installing and the gas-sealing check of the space between the pipes in the well. Underground works are being performed in accordance with the mining project.

After completed underground works, activities on the above-ground part of pilot geothermal power plant construction will begin, namely (i) construction work (three building bases, and sewerage, water and electrical lines), (ii) work on electrical and mechanical installation, (iii) modeling and long-term monitoring of trial operation, (iv) geothermal potential of abandoned oil and gas wells assessment in Slovenia and (v) guidelines for the new project development preparation. Start-up tests of first geothermal power plant in Slovenia are planned for June this year.

Practically confirmed new designed concept will enable utilization of other abandoned wells in Slovenia as well as abandoned wells around the world.

More information about the project is available at the link: https://en.unesco.org/international-geoscience-programme/projects/636

Numerous countries already presented their experiences (Spain, Italy, Canada, Colombia etc.). Their presentations are available on google docs with registered access to the geotheroom portal: https://docs.google.com/forms/d/e/1FAIpQLSd0qBQJz4M6oeRy3XEhFIxYM6bG092aAkufb8FRI2KLh0i65w/viewform.