Integration of large-scale heat pumps in the district heating systems of Greater Copenhagen

Abstract

This study analyses the technical and private economic aspects of integrating a large capacity of electric driven heat pumps (HP) in the Greater Copenhagen district heating (DH) system, which is an example of a state-of-the-art large district heating system with many consumers and suppliers. The analysis was based on using the energy model Balmorel to determine the optimum dispatch of HPs in the system. The potential heat sources in Copenhagen for use in HPs were determined based on data related to temperatures, flows, and hydrography at different locations, while respecting technical constraints. The Balmorel model was developed further in order to provide a better representation of HPs, for analysing the seasonal variations of COP, and to represent the difference in performance of HPs connected to either distribution or transmission networks. The optimization yields roughly 3,500 full load hours (FLH) for the HPs connected to the DH distribution networks when considering a current scenario. In a zero carbon-dioxide emission scenario expected in year 2025, approximately 4,000 FLH, are achieved. In the case where HPs are connected to the DH transmission network at elevated temperatures, their operation decreases by roughly 1,000 FLH. No significant impact was found when comparing fixed and varying operation characteristics of the HP.

Power-to-Heat for Renewable Energy Integration: Technologies, Modeling Approaches, and Flexibility Potentials

“…On the contrary, Bach et al [25] bring forward that the application of a variable or fixed COP for centralized heat pumps has little influence on model results.…”

“…Other analyses for different Nordic countries also include a future switch from natural gas to heat pumps and to a lesser extents to electric boilers [64] for decentralized heat supply, alongside continued district heating [31]. In a study on the district heating system of Copenhagen in 2025, Bach et al [25] stress a complementarity between heat pumps and CHP plants: while the former produce heat in hours with low electricity prices, the latter conversely do so in high-price hours. In any case, heat pumps would replace some CHP production; moreover, their full-load hours would be highest when connected to the heat distribution grid.…”

“…Many models are long-standing projects that evolved from electricity sector analyses into combined heat-and-electricitysystem analyses. Prominent examples are the models BALMOREL [25,28,29,31,64,65], TIMES [48,49,50,36], and energyPLAN [27,33,34,63,30]. While the first two are cost minimization models, energyPLAN seeks to minimize consumption of fossil fuels.…”

“…Several reviewed models [25,41,43,51] apply such formulations. Accounting for temperature dependence, relation (1a) transforms to (1c).…”

“…Studies on the structure of heat supply shed light on trade-offs between power-to-heat technologies [25,33,30]. Specifically, several analyses endogenously determine an optimal capacity mix of heating technologies [57,59,64,43,60,36,31,48,50,44].…”