THE POSSIBLE ROLE OF SEASONAL THERMAL STORAGE FOR DECARBONIZING AN AUSTRIAN DISTRICT HEATING NETWORK
By Ralf-Roman Schmidt, Senior Research Engineer, AIT Austrian Institue of Technology
Gerhard Totschnig, Research and Development Engineer, AIT Austrian Institute of Technology
Bernhard Mayr, Junior Research Engineer, AIT Austrian Institute of Technology
Seasonal thermal storage is a key element in decarbonising district heating networks. It can shift excess heat in summer from industrial waste heat, geothermal energy, heat pumps, and solar thermal energy to the winter and make an important contribution to covering the winter load and thus reducing the demand for fuels (see Figure 1).
This contribution describes the possible role of seasonal thermal storage for decarbonizing district heating networks in Austria based on a concrete case study, where a decarbonization strategy has been developed for the local utility. The analyses show that seasonal storage can be economically feasible if their storage capacity is maximized using heat pumps, low-cost
surplus heat is available (i.e., low electricity prices or surplus from geothermal energy), and the costs of biofuels are high. However, some challenges for their integration still need to be overcome, including high space requirements, technology availability, and cheap biofuels.
Figure 1: Top: Temporal mismatch between the demand for heat and the supply of waste heat and other renewable heat sourc- es as well as heat pumps in summer, use of (fossil) fuels to cover the heat demand in winter; bottom: With the help of seasonal thermal storage, surpluses from the summer are brought into the winter and contribute to covering the heat demand
22 HOTCOOL no.5 2024
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