Integration of Renewable Energy Sources into Low-Temperature District Heating Systems: A Review

Ioan Sarbu (), Matei Mirza and Daniel Muntean
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Ioan Sarbu: Department of Civil and Building Services Engineering, Polytechnic University Timisoara, Piata Victoriei, no 2A, 300006 Timisoara, Romania
Matei Mirza: Department of Civil and Building Services Engineering, Polytechnic University Timisoara, Piata Victoriei, no 2A, 300006 Timisoara, Romania
Daniel Muntean: Department of Civil and Building Services Engineering, Polytechnic University Timisoara, Piata Victoriei, no 2A, 300006 Timisoara, Romania

Energies, 2022, vol. 15, issue 18, 1-28

Abstract: This article presents a complex and exhaustive review of the integration of renewable energy sources (RES) (specifically solar, geothermal, and hydraulic energies and heat pumps (HPs)) and the improvement of water pumping in district heating systems (DHSs) focused on low-temperature systems, to increase energy efficiency and environmental protection. For this aim, the main components of a DHS and the primary RES with applications in DHSs were described briefly. Finally, several case studies regarding the DHS in Timisoara, Romania, were analysed. Thus, by integrating water source HP (WSHP) systems in cooperation with solar thermal and photovoltaic (PV) collectors and reducing the supply temperature from 110 °C to 30 °C in DHS, which supplies the water radiators to consumers in a district of this city in a 58/40 °C regime of temperatures and produces domestic hot water (DHW) required by consumers at 52 °C, a thermal energy saving of 75%, a reduction in heat losses on the transmission network of 90% and a diminution of CO 2 emissions of 77% were obtained. Installed PV panels generate 1160 MWh/year of electricity that is utilised to balance the electricity consumption of HP systems. Additionally, mounting pumps as turbines (PATs) for the recovery of excess hydraulic energy in the entire heating network resulted in electricity production of 378 MW, and the variable frequency drive’s (VFD) method for speed control for a heating station pump resulted in roughly 38% more energy savings than the throttle control valve technique.

Keywords: district heating; distribution network; low-temperature; solar energy; geothermal energy; heat pump; micro-hydro turbine; variable-speed pump; energy saving; CO 2 emissions (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (7)

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