Energy and Heat Contracting for Fellbach Wastewater Treatment Plant: Conception, Planning, Implementation, and Operation

Conception, planning, implementation, and operation of an energy and heat contracting model for the Fellbach wastewater treatment plant as part of an overall energy concept: The concept considers the EU Municipal Wastewater Directive (RL 2024/3019) and includes power generation from sewage gas (e.g., through installation of one or more combined heat and power plants, including evaluation of potential grid-independent operation), installation of a natural gas boiler for peak heat load coverage or as a redundancy system, direct use of generated electricity within the treatment plant, evaluation and implementation of an additional photovoltaic system, and evaluation and integration of a battery storage system to increase the degree of self-sufficiency. The goal is a technically and economically optimized supply concept for emission reduction and increased supply security with a high degree of self-sufficiency and stable supply. The operating concept must present measures for fail-safety and on-site personnel availability for plant operation. An operating period of 15 years, possibly with an extension option, is planned. The timeline foresees concept deepening, planning, and start of execution (at least component ordering) from December 2026, with the possibility of fulfilling the requirements according to § 6 I No. 1 Combined Heat and Power Act. Construction will commence from January 2027, with commissioning by July 2027 at the latest. Currently, two sewage gas CHP units have been out of service since November 2024; a rented sewage gas CHP with 100 kW electrical output is temporarily in use. Peak thermal load is covered by a 350 kW gas boiler that requires renewal. A photovoltaic system with 61 kWp is already present on the treatment plant roof. The renovation of existing sewage gas storage tanks is also planned.

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