18 May 2017

P.3.7.1 Efficient solution for large heat pumps: wastewater heat recovery

Inside the sewer there is a hidden and rarely used, stable temperature energy source to be found: the communal, household and industrial wastewater. A heat pump based technological solution has been developed to harness and utilize energy resided in wastewater to heat and cool buildings. This means for a city like Rotterdam the potential of min. 50 MW energy-generation!
The challenges are to use this valuable resource on site amongst city circumstances, to make it upsizeable to several MWs requirements and to achieve a highly efficient system (COP above 6!) in order to make it financeable.
Driven from the technology solution’s “independence” from the sewers (nothing installed inside the pipeline) the system’s implementation is flexible, after eight years of development its possible size only depends on the wastewater flow.
The technology developed has been monitored during operation for over 5 years at different locations (sizes: 1 – 3.8 MW). Learning from this unrivalled operational experience and the monitored performance data the technology solution has been improved through minimizing energy consumption, evolving efficiency of heat exchange, optimizing maintenance requirements and SCADA system.
Additional benefits recognized during realization of the projects:
? Free allocated and valuable spaces on rooftops
? Combined and centralized heating and cooling system
? Potential external use of remaining heating or cooling capacities
? Satisfying simultaneous heating and cooling needs
? Use sewage as heat transporting medium
Discussion points: potential unrealized, possible end users and their benefits, influence on the thermal management of a wastewater treatment plant.