Monitoring an innovative cold district heating network with decentralized heat pumps and sewage water as heat source
Abstract
The innovative heating network of a new development area in the city of Wiesbaden (Germany) is presented. The system uses waste heat from a sewer as the only source for heating via a cold heating network. Decentralized heat pumps in the buildings are used to raise the temperature level and electrical heating elements provide back-up. Possible advantages include high efficiency due to consistent wastewater temperatures and minimal noise and visual impact. The 2023 monitoring results are presented, showing that the heat pump systems provided 343 MWh to 5 multifamily buildings. Due to a leakage-related outage of the wastewater heat exchanger lasting several months and various problems in the operation of the heat pumps, the efficiency goals could not yet be fully achieved in operation. The total electricity consumption for heat supply in 2023 was 128 MWh. The average Seasonal Performance Factor (SPF) ranged from 2.7 (including network shutdown and use of electric heating elements) to 4.1 (fault-free operation).