Techno-ökonomische Analyse erneuerbarer Wärmeerzeugungsprojekte im Großraum Graz im Vergleich zum Heat Highway Steiermark

The project Heat Highway aims to decarbonize the heat supply in its target region, including the ¿Großraum Graz¿, by implementing a Supra-Regional District Heating Network. This Master¿s thesis investigates how other renewable heat generation projects perform, either as alternatives or as supplements to the Heat Highway, from both an economic and technical perspective to supply Großraum Graz. An extensive literature review was conducted to establish all economic and technical input parameters. Based on this, a techno-economic-analysis (TÖA) was carried out for four selected heat generation projects (Tiefengeothermie, Sonnenspeicher Süd, Energiewerk Graz and Energetische Klärschlammverbrennung). The focus was on determining the levelized cost of heat (LCOH) for three individual scenarios for the years 2019, 2021, 2022, and 2023. Sensitivity analyses were also performed to evaluate the impact of changes in key parameters (CAPEX, OPEX, system lifetime). The results show, that the projects Tiefengeothermie and Energiewerk Graz are, in most cases, the most economically viable projects. In contrast, Sonnenspeicher Süd and Energetische Klärschlammverbrennung generally result in higher LCOH-values. Scenario 2, in which the considered technologies are only used after covering the base load with existing sources such as biomass and industrial waste heat, proved to be the most realistic scenario. The calculated annual heat output s closely match the planned outputs in the literature. A comparison of LCOH with the Heat Highway¿s unit costs demonstrates, that Tiefengeothermie and the Energiewerk Graz are particularly competitive. Both, LCOH and unit costs fluctuate annually due to various influencing factors. In 2023, the LCOH of all projects in two of the three scenarios fell below the Heat Highway¿s unit costs. This is because the Heat Highway relies on natural gas during periods of high demand and gas prices were exceptionally high in that year. In comparison, the unit cost of the Heat Highway in 2021 was lower than the LCOH of all heat generation projects in scenario 2. Additionally, the thesis examined the full-load hours required for each project to be able to be economically integrated into the Heat Highway system. The analysis shows, that the heat generation projects should not only be considered as competitors, but also as additions. Their integration into the Heat Highway could reduce unit costs, as the current system still depends on expensive fossil fuels. Furthermore, such integration would only benefit consumers in Großraum Graz, but also those throughout the entire Heat Highway region.