Szeged implements Europe’s Largest Geothermal District Heating Renovation

Szeged is the third largest city of Hungary, with a population of about 160 000 inhabitants. The city approved its Sustainable Energy and Climate Action Plan (SECAP) in 2018, committing to a 40% reduction of its overall GHG emissions by 2030. The transformation of the heating sector is largely contributing to this emissions reduction. 

Szeged's heating strategy

The district heating (DH) system of Szeged provides a total energy output of 843 700 GJ/year to the end-users via a network of 250 km. The city and its surroundings have exceptional hydrogeological features and geothermal-based bathing. However, until very recently, the sole energy source of the heating system in Szeged was imported natural gas, making the DH company the single largest local emitter of CO₂. Following the initiative of making Szeged the greenest city in Hungary, the DH company SZETAV decided to integrate renewables in its energy portfolio. 

Since 2018 SZETAV and its partners have carried out the largest geothermal district heating renovation in Europe. Now almost complete, the new integrated heating system is about 60% less polluting, 50% of its energy supply is local and its operation is more efficient and economical. The project included drilling 1.7-2 km deep thermal wells in Szeged and its surroundings, to produce 70 m³/h thermal water at 90°C. As the water injected in the system still has a lot of energy, the DH network could be expanded in the future. 

The DH company of Szeged supplies heat and domestic hot water to 27 256 apartments (about 30% of all the households) and 433 non-residential end-users. With the help of deep geothermal energy, nearly 20 million m³ of natural gas were replaced with 606,958 GJ of geothermal energy per year, reducing the greenhouse gas load of the city of Szeged by 39299 tons/year, improving air quality and security of supply.  

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^{North 1/A heating plant © SZETAV} 

^{Open air movie night at the Rokus district heating plant © SZETAV}

^{School children visit the Rokus pumping facility © SZETAV}

Main challenges to detoxify heat and next steps

• The hot water is reinjected in the system at ~40-50°C. This is a huge waste of energy that could be used to heat more buildings (currently not on the grid) or, with the help of heat-pumps, reheated and used again to supply the buildings already on the grid.
• The upper Pannonian sandstone reservoir has a large methane content and extracting water would mean extracting methane too – utilization of this greenhouse gas is of utmost importance and constitutes the next step in detoxifying the district heating in Szeged (funds to implement this project are already secured for installing gas boilers at the production wells to burn the methane and increase the temperature of the extracted water).
• Decreasing the energy need of the end-users would result in a higher proportion of geothermal in the energy mix – insulating the buildings would be a major step towards lowering the temperature required to supply heat. 

Where Szeged is in its heat strategy

^{Layout of geothermal systems in Szeged © SZETAV}

Discover more about the geothermal systems in Szeged here! 

Szeged's Heat Detox

Key Heat Figures

• Emissions related to heating: 60,000t CO₂ / year (before integrating geothermal) – now around 60% less
• Km of DHC currently: 250km
• Percentage of renewables in heating system: 50%. The rest is natural gas.
• Other interesting figures: 20 million m³ of natural gas have been replaced with 606,958 GJ of geothermal energy per year, reducing more than half of the GHG emissions. 

Covenant Figures

•  Signatory to the Covenant of Mayors since: 2017
• Emission reduction ambitions: 
  % GHG emissions reductions by 2030: 40%