On the way towards smart energy supply in cities: The impact of interconnecting geographically distributed district heating grids on the energy system

• Published in: Energy (Oxford) 2017-10, Vol.137, p.941-960
• Main Authors: Dominković, D.F., Bačeković, I., Sveinbjörnsson, D., Pedersen, A.S., Krajačić, G.
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carbon dioxide emissions; Case studies; CO2 emissions; Costs; District heating; Emissions; Energy; Energy costs; Energy demand; Energy efficiency; Energy system optimization; Geographical distribution; GIS; Industrial wastes; Interconnections; Local Communities; Optimization; Renewable energy systems; Supply & demand; Waste heat; Zero carbon
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2017.02.162

A linear continuous optimization model with an hourly time resolution was developed in order to model the impact of subsequent interconnections of different DH grids. The municipality of Sønderborg was chosen for a case study and interconnections of five currently disconnected DH grids were assessed. Moreover, the impact of industrial waste heat on the DH supply was also assessed. In the reference year (2013) two out of four interconnections proved to be economically viable. The results for the future energy system (2029) showed that interconnecting geographically distributed DH grids reduces primary energy supply by 9.5%, CO2 emissions by 11.1% and total system costs by 6.3%. Inclusion of industrial waste heat in the fully interconnected DH grid reduced primary energy supply for an additional 3%, CO2 emissions for an additional 2.2% and total system costs for an additional 1.3%. The case of the future energy supply system with interconnected DH grids and installed industrial waste heat recuperation results in the lowest primary energy demand, emissions and costs. Finally, the benefits of the interconnected DH grid, in terms of system flexibility, CO2 emissions, total costs and energy efficiency, proved to be much greater in the future energy system. •A new model for integration of district heating (DH) systems was developed.•Connecting DH grids is more beneficial when more intermittent sources are present.•Integration of DH systems allows better utilization of cheaper technologies.•Waste heat from industry improves the economy of DH systems.•Heat pumps are important integration technology of power and DH sectors.