InnoA2_up: Innovative Use of Wasteheat using sewers for energy transport

Wastewater - a new energy option?

By use, water becomes wastewater. Whether it is showering, handwashing, washing or cooling processes in trade and industry: In many decentralized places, water is supplied with heat energy, which is discharged into the sewage system without being used or even actively cooled down. Municipal wastewater in the canal has a temperature ranging from 10 to 20 degrees Celsius over the course of the year. This temperature level can be increased by using decentralized heat sources, transported through the sewer and “downstream“ energetically used by heat consumers. The high efficiency of the approach results, on the one hand, from the utilization of waste heat, which would otherwise remain unused (or even actively cooled down), and, on the other hand, from the dual use of the existing sewer infrastructure, which acts as a heat transport pipeline.

The overall objective of this second project phase “Implementation planning for pilot plants for the innovative use and distribution of waste water via sewerage“ (InnoA2-up), is the detailed elaboration and evaluation of specific implementation options for flagship projects for the development of previously unused decentralized waste heat potential through heat transport and distribution to heat consumers in the existing sewer system.

The project builds on the results of the first phase “Innovative waste heat utilization through heat distribution via the sewage system - InnoA2“ regarding the basic feasibility, the effects of elevated temperature levels on the sewer and the requirements of required technical components such as heat exchangers, supply lines etc.

Figure 1: Utilization of waste heat through distribution via existing sewer systems

In the urban area of Luenen, Germany, the existing research results are to be put into practice on the basis of two options with very different boundary conditions, and the feasibility of both options.

The focus of the work of ISI is on the sustainability assessment of the project as well as on new stakeholder constellations and innovative business models. The later are crucial to support a successful market launch of the new approach as well as to contribute as a starting point for the implementation of fundamental transitions processes in the water industry.

Dual use of infrastructures can provide high resource- and cost-efficiency for heat distribution and provisioning. This enables to supply even areas with lower heat density with renewable heat that would otherwise not be exploited economically by heat networks. This supports the international competitiveness of German companies in the field of plant engineering and water technology.
For municipal companies in the field of wastewater treatment and sewer operation, the concept opens up new business areas. In addition to the technical feasibility and the sustainability assessment of the concept, the implementation in the Luenen model area is the focus of the project in a practice-oriented manner. This includes the preliminary design with cost calculation for the exemplary implementation of a pilot line.


01.09.2018 - 31.03.2021


  • German Federal Ministry of Economics and Energy


  • Stadtbetrieb Abwasserbeseitigung Lünen AöR (SAL) [Project Management]
  • Dipl.-Ing. Udo Schratz
  • University of Kaiserslautern
  • Department of Construction Management, Faculty of Civil Engineering
  • Prof. Dr.-Ing. Karsten Körkemeyer