SWITCHING THE DISTRICT HEATING OF SZEGED TO GEOTHERMAL

By Dr. Tamas Medgyes, Chief Operations Officer at District Heating Company of Szeged

HISTORY

The Szeged heating system has 23 heating circuits with a total installed capacity of 204,172 MW in 1-12 MW boilers, providing 843,700 GJ/year of energy for heating and domestic hot water (DHW) production through 239 heat centres and 215 km’s of underground pipelines. Based on the proposition of engineers and hydrogeologists who had by that time already implement several successful geothermal projects in the region, a decision was made in 2015 to integrate renewables into the district heating system of Szeged, in order to reduce the emissions of gas-based heating plants, and to improve the economy of the operation.

THE PROJECT

The 70 million EUR development is financed from the European Regional Development Fund (ERDF) and private investment. Within the framework of the project, 9 thermal wells each 1700-2000 m deep are established to produce 90°C thermal water at a rate of 70 m3 per hour. The extracted water travels through 30 km long, newly laid, pre-insulated pipeline to 9 refurbished heating plants, where its thermal energy is utilized through heat exchangers. After utilization, the water is returned to the subsurface reservoir through 18 injection wells.

Thanks to the connection of the heating circuits carried out parallel with this project, the 9 production wells provide heat energy for a total of 15 district heating districts. Since these are the areas with the largest number of users, when completed, approximately 98% of all district-heated apartments in Szeged will receive geothermal energy; in very cold weather and during peak DHW use periods, however, additional gas-based boiler operation will always be necessary.

The project is ongoing, and the commissioning of the entire system is expected in the 2023/24 heating season. As a result of the project, a total of nearly 20 million m3 of natural gas will be replaced by 600,000 GJ of geothermal energy per year, reducing Szeged's greenhouse gas load by 35,000 tons per year, improving air quality and the security of supply.

RESEARCH AND DEVELOPMENT

Dozens of balneological, agricultural and district heating geothermal systems operate in the Southern Great Plain Region, and Szeged has become a significant base for the geothermal industry and research and development. Particularly lively work is being done in the field of scaling management and injection, pioneering experiments are underway in chemical water treatment, and the utilization of disused thermal wells as deep heat exchangers.

Geothermal developments in Szeged are surrounded by significant international interest. SZETÁV and its partners participate in H2020, EEA Interreg, HorizonEU and other collaborations including the CROWDTHERMAL (SZETÁV) and User4GeoEnergy (InnoGeo) projects. Always open to participating in ambitious R&D projects, SZETÁV and its partners have made Szeged a popular case study for international consortia operating in the field of renewable energies, and rightly so: the geothermal transformation of the district heating of medium-sized cities is a big step towards a carbon-neutral, sustainable Europe.

Well drilling and heating plants can be visited in an organized form, the project is a popular topic for professional internships, theses, PhD works, and it is also a great opportunity for decision-makers and professionals to gain first-hand experience of a large-scale renewable energy project, underground water management and environmentally conscious, economically sound system operation protocols.