The Role of Heat Pumps for Decarbonising and Optimizing the Linz District Heating and Cooling System
LINZ AG's district heating (DH) network is the second largest in Austria with a heat generation of 1.151 GWh. It is currently supplied via gas (55.1%), biomass (13.5%) and waste incineration (31.4%). The aim of Linz AG is to reduce the fossil fuel-based generation to zero by 2040. Further, a district cooling (DC) network is under planning with a total generation capacity up to 40 MW. For determination of a cost-optimal district heating and cooling (DHC) generation portfolio, a pathway optimization is conducted in this study. Therefore, scenarios for energy prices, heat demand etc. are defined and key technology options are evaluated, including different possibilities for heat pumps (HPs) integration. The DHC system is modelled, and an optimizer is used with the objective function to minimize the total system costs (net present value) up to 2040, considering the service lifetime of the existing plants and the maximum availability of renewable fuels. Results show that HPs play an important role, since they can: 1) enhance the system efficiency via flue gas condensation; 2) use low temperature heat sources for decarbonizing the DH supply; 3) increase the storage capacity by increasing the temperature lift; and 4) provide cooling economically, simultaneously suppling waste heat to the DH network.