Fifth-generation district heating and cooling (5th DHC) systems offer promising approaches to decarbonizing space heating, cooling and domestic hot water supply. By using these systems, clustered buildings combined with industrial waste heat can achieve a net-zero energy balance on a variety of time scales. Thanks to the low exergy approach, these systems are highly efficient. As part of the Smart Anergy Quarter Baden (SANBA) project, the thermal energy grid simulation tool TEGSim has been further developed and used to design an ultra-low-temperature district heating (ULTDH) network with hydraulic and thermal components fitted to the specific regional characteristics of the investigated case. Borehole thermal energy storage (BTES) used as seasonal storage ensures long-term feasibility. The annual discrepancy of input of thermal energy provided by space cooling and output of energy demanded by space heating and domestic hot water is supplied by an external low-grade industrial waste heat source. This paper presents the functionality of the simulation and shows how to interpret the findings concerning the design of all components and their interplay, energy consumption and efficiencies.

Deep geothermal resources for heat supply and waste heat potentials were assessed and measured for a high-temperature dairy plant. For the industrial waste heat, a borehole heat exchanger (BHE) seasonal storage was configured and simulated after an extensive investigation of shallow geothermal resources. We developed a concept for the subsequent use of the residual and waste heat from the plant in a low-temperature heating and cooling (LTHC) grid for the neighbouring former military camp “Martinek-Kaserne” with a future use as mixed-use urban quarter were investigated in two projects. The modelling of the deep geothermal resources showed that of the three potential reservoirs one is most feasible for geothermal heat supply with temperatures between 129 and 146 °C, which could be used with a high-temperature heat pump for process heat. The waste heat in all sub-processes of the dairy plant were measured over 18 months to identify the most suitable waste heat streams with regard to temperature and continuity. The results showed that 25 % of the waste heat from a sub-process of the plant (fresh products logistics) is sufficient to provide heat for the adjacent LTHC grid with a total energy demand of 3428 MWh per year. The simulation of the BHE field resulted in 96 BHE with 180 m depth for a dis-/charging capacity of 643.7 MWh and 20 decentral heat pumps in the buildings. The BHE field operates quite balanced with only 12.8 MWh of difference in the annual balance. The results of the feasibility study for deep and shallow geothermal resources, and the assessment of the industrial waste heat show that the whole cascade of high-temperature heat for industry to low-temperature heat for the LTHC grid could be realized at the investigated site.

In Austria, heat supply accounts for more than half of the country’s final energy consumption, with low-temperature heat below 100 °C for space heating and domestic hot water making up around 61% of that. Approximately 47% of total heat consumption is still covered by fossil energy sources. In the energy-intensive industrial sector in particular, previously unused excess heat is available for cascading use. This publication presents industrial excess-heat potentials identified through individual case studies and a nationwide survey. According to the comparison of figures, in an ideal scenario roughly 65% of private space heating consumption could be covered by excess heat. In addition to conventional district-heating systems, which represent the current state of the art, new options are emerging for distributing excess heat, including supra-national district-heating networks for longer transport distances. For challenges associated with predominantly low temperatures, mature and proven solutions exist through the combination of heat pumps and anergy networks. Increasing the integration of excess heat is absolutely essential in order to raise the efficiency of industry and further decarbonize the heating sector.

Zusammenfassung: Die Montanuniversität Leoben hat sich zum Ziel gesetzt, die Forschung im Fachbereich Energie in Form eines Exzellenzclusters Energie zu koordinieren und zu intensivieren, um den Herausforderungen der dringend notwendigen Transformation des Energiesystems gerecht zu werden. Die Ziele des Exzellenzclusters Energie sind eine verbesserte Sichtbarkeit nach Außen bei angehenden Studierenden, der Forschungswelt sowie in der Industrie. Dabei soll die Montanuniversität Leoben als Institution mit Energieforschungskompetenz wahrgenommen werden, um mit Energieinnovationen aus Österreich die heimische Industrie zu stärken und einer Marktführerschaft in Bereichen der Energie gerecht zu werden. Im Rahmen einer ersten systematischen Erhebung energierelevanter Forschungsprojekte wurden mehr als 160 Projekte identifiziert, an denen Forschende im Ausmaß von über 150 Vollzeitäquivalenten beteiligt sind.