As part of the "Federal Funding for Efficient Heating Networks" (BEW), a concrete decarbonisation path for district heating in Halle is to be developed with the help of a heat transformation plan (WTP) in order to achieve greenhouse gas neutrality in heat supply by 2045. The potentials of a decarbonised district heating supply in the Halle (Saale) area are to be analysed and demonstrated and supported by the necessary measures on the basis of future development paths. Based on this, an adequate district heating target network must be developed. EVH GmbH strives to develop resilient strategies that set the path until 2045 and advance and enable the implementation of innovative and sustainable projects.

The Halle-Nord sewage treatment plant was built in 1998, is designed for 340,000 inhabitants (Halle currently has a population of approx. 245,000) and can biologically treat up to 75,000 cubic metres of wastewater per day at full capacity. The sewage treatment plant was built on a modular basis and can therefore be expanded at any time. Of the 30 hectares, 20 hectares are currently cultivated.

So far, the surplus heat from the 3 CHP units (renewed in 2022 with type TCG 3016 V12 from Caterpillar Energy Solutions GmbH) that is not required for the company's own needs has been released into the environment by means of an air cooler in summer and the additional peak load heat is provided in winter with a natural gas boiler (1,320 kWth).

The Halle-Nord sewage treatment plant will receive a district heating connection in order to feed the excess heat from the sewage gas CHP units into the flow of the district heating network at approx. 85 °C in summer and to obtain the higher heat demand of the sewage treatment plant from the district heating network in winter. The district heating connection, consisting of a house connection line and a house connection station, will go into operation at the beginning of the 4th quarter of 2023. The station is designed for a thermal output of 850 kW. In the case of the house connection pipeline with a nominal diameter of DN 250, the heat fed in by the sewage treatment plant by means of heat pumps has already been taken into account. The connection point for the surplus heat, which is to be fed into the district heating network via the house connection line, will be built retrospectively in the area of the house connection station.

With the integration of the sewage treatment plant into the district heating network completed in 2023, the supplementary objective of additional generation of environmental heat from the treated wastewater with a temperature range of 12° C (winter) to 22° C (summer) results in a temperature reduction of approx. 8 Kelvin by means of heat pumps. The treated wastewater is to be cooled down to approx. 4 °C (winter) before being discharged into the Saale. The heat extracted from the wastewater can only be used in winter and only to a small extent (approx. 200 to 700 kW) in the sewage treatment plant to cover the peak heat demand. The majority of heat is to be fed into the district heating network all year round with a temperature level of up to 120° (VL)/ 65°C (RL) in winter and 80° C (VL)/ 55 °C (RL) in summer.