Together with Stadtwerke Rosenheim, FfE is preparing a feasibility study for the implementation of a fourth-generation heating network in Rosenheim. The first step will be to transform an existing local heating network into a 4.0 heating network. In the later course of time, the supply bound to the heating network of an adjacent development area will be connected to it. The project is funded by the Federal Office of Economics and Export Control (BAFA) and started in January 2018.
What are criteria for a fourth generation district heating network?
Fourth-generation heating networks are those whose flow temperatures do not exceed the 20 - 95 °C range. These low system temperatures allow the integration of a high proportion of renewable heat sources (solar thermal, environmental heat, biomass) and waste heat. In addition, low distribution losses are achieved, so that heating networks 4.0 distribute the heat very efficiently. In order to determine inefficiencies and, if necessary, to better identify weak points, continuous monitoring of the networks is also carried out. Through the integration of heat pumps and other power-to-heat technologies, flexibility can also be provided for the electricity market and grid. An overview of relevant technologies can be found in Figure 1.
Figure 1: Interconnection of relevant components for grid-bound heat supply based on renewable energies and waste heat
Information on the project with the Public Utilities of Rosenheim
The project will determine both the potential for reducing losses and the integration of renewable energy sources.
Reduction of distribution losses
A reduction of thermal losses can be achieved above all by strengthening the insulation or lowering the system temperatures. Since the existing network is sufficiently insulated and additional insulation would require an immense amount of installation work, the project is investigating various operational options to reduce the temperature levels.
For this purpose, the entire network is first divided into different network strands, which can then be individually set to the correct temperature according to seasonal variations.
Due to the low demand for domestic hot water, it will be investigated whether it is economically viable to switch off two partial strands in summer compared to decentralised, current-based heating of the domestic hot water. Furthermore, it will be investigated how high the energy savings are through the selective loading of decentralised hot water storage tanks and whether this type of loading leads to cost savings.
Innovative heat supply
Two supply concepts are examined more closely in order to provide the required heat. The heat supply concepts considered are a low-temperature network with decentralised heat pumps. On the other hand, the series connection of different heat generators (heat pump, CHP, primary network) in the form of a "heat dispatch centre" is investigated.
Further information on the project and the technical requirements for a Heating Network 4.0 can be found here.
A summary of the project results was presented in September 2018 at the International Symposium on District Heating and Cooling in Hamburg: Transformation of an existing into a Fourth Generation Heating Network.
The concept of the Heat Dispatch Centre was presented to the expert audience and discussed with them at the workshop of the Energy Research Network Hamburg on the topic "Sustainable District Heating and Cooling - Digitalisation and Energy Efficiency" in Hamburg in September 2018: Heat Dispatch Centre - Symbiosis of renewable generation units for sustainable thermal energy supply.