The supply of heating and hot water implies large amounts of energy, which to date come mostly from fossil sources. To counteract climate change and pursue the decarbonisation of cities, renewable heat sources such as wastewater have been increasingly coming into focus in recent years. Wastewater contains large amounts of chemicals and thermal energy, and is produced wherever human activities take place; this means that it is not only a renewable but also a constant and reliable source of energy and heat.
This project, starting from the Kapfenberg wastewater treatment plant, investigated possible innovative approaches on whether and how energy (heat) recovery from wastewater could contribute to the public heating supply.
So far, the only energy-related aim of wastewater treatment plants has been self-sufficiency but usually, the energy produced by this type of plant may far exceed its self-supply needs. Consequently, a wastewater treatment plant could also be re-imagined and developed as a local energy/heat cell and this is possible with the same kind of plants across Europe, making the heating and hot water supply local, climate-friendly, renewable and sustainable.
The investigations confirmed the technical feasibility of the selected implementation scenario. It can develop both available heat sources at the wastewater treatment plant, therefore it satisfies two types of heat demand – the wastewater treatment plant’s internal demand, and external demands.
Consequently, the project supports the exploitation of what is so far an unused heat potential (the wastewater heat from the wastewater treatment plant’s effluent), and the more efficient use of the available energy sources. Wastewater heat specifically used for internal low-temperature applications (e.g. digester heating) makes the high energy from the sewage gas/biogas combustion available for other, external uses.
The wastewater treatment plant as a local, renewable and reliable energy/heat cell represents a key element for the ongoing intent of an energetic transition and can thus play an essential role in the sustainable energy supply of the future.