Sensitivity analysis of the conception of small scale district heating networks on the thermal conductivity of the surrounding soil

Heat distribution via pre-insulated plastic bonded piping systems will become of major importance for covering the primary energy consumption of EU and will be of vital importance for the energy and heat turnaround. Utilizing efficiency potentials of combined heat and power (CHP) and integrating (industrial) waste heat and renewable energy contents within these grids, low temperature (and low-ex) heat sources might be exploited. Thus, energetic contents unsuitable for electrical energy supply are utilized in order to diminish greenhouse gas emissions and minimize primary energy needs. Distribution of heat requires accurate planning and network design for the expected service time of several decades. This applies for existing networks as well as for future networks. During planning and conception different load scenarios (of today and in future) must be considered. Since the design of existing networks was done in the past, this paper focusses on the requirements for the conception and planning of heating networks in the near future. Because of low temperature (and low-ex) heat sources, the expansion of district heating networks in EU will be linked to modifications in the network design and planning. A sensitivity analysis was carried out for relevant input parameters in low temperature networks. The analysis showed a significant influence of the conductivity of the bedding material as well as the overburden height on heat losses. For the given set of reference parameters, the energy efficiency potential of systems for heat distribution is approximately 10 %.