Heat network concept for the Slachthuis site

Aquafin and Fluvius wanted to investigate whether it was possible to use waste heat from the wastewater treatment plant (WWTP) as a source to supply sustainable heat to the Slachthuissite. That is the new residential area under development in the north of the city of Antwerp. For this purpose, a feasibility study and concept study were needed.

On the one hand, the different ways of producing heat as well as the phasing of heat production had to be investigated in order to design an optimal system. On the other hand, the project included drawing up and calculating the business case for Aquafin as a heat producer and analysing the consequences of connecting neighbouring expansion areas, such as the Stuivenberg neighbourhood, to the heat production system.

Firstly, Antea Group was responsible for variant analysis and determining the optimal technical combination of heat sources, taking into account the phased connection of future heat demand. In the assessment, we took into account the technical requirements and security of supply, sustainability requirements, cost efficiency and flexibility of the concept.

Secondly, we prepared a meticulous business case for supplying heat to the district heating network. A detailed overview of all costs (CAPEX, OPEX) and revenues was made and this was based on a thorough process simulation of each of the variants. Heat demand and supply were optimally matched on an hourly basis, in line with the technical requirements and efficiency of a two-stage heat pump - a type of high-temperature heat pump - under different operating conditions.

As the third part of the assignment, we studied the impact of expansions on heat production and distribution, both technically and financially. This involved taking a closer look at the following:

• What adjustments are needed to the technical concept and what additional investments are required to future-proof the plant?
• Technical concept and additional investments for heat distribution via the district heating network (such as transfer stations, additional controls, booster stations, etc.).
• Impact on the internal installations at Aquafin's WWTP..

Finally, we conducted sensitivity analysis of all risk factors (e.g. effluent temperature, co-firing, heat pump phasing, etc.) that affect the Seasonal Performance Factor (SPF) of the heat pump and profitability of the project. That factor determines the efficiency of the two-stage heat pump. The financial model was carefully developed so that the client could easily evaluate the impact of different parameters on sensitivity.

With the results of this project, we laid a solid foundation for the implementation of a sustainable heat production system based on residual heat from the WWTP. This system will make a significant contribution to reducing CO2 emissions, increasing energy efficiency and promoting a circular economy in the City of Antwerp.