Ecopower has achieved an important milestone in the development of the Belgian pilot site within the Interreg NWE project AquaCOM. A few months ago, they appointed an external engineering firm. This firm had the task of ensuring a reliable heat supply to the residents of the mill site by mapping the size of the components and determining the investment and operating costs for the project.
The results of the study allowed Ecopower to shape the business case to identify the technical and financial feasibility. In consultation with the engineering firm, two scenarios were selected to be worked out in detail.
Scenario 1: 40°C low-temperature heat grid: central heat pump supplies heat at 40°C. Individual booster heat pumps installed in the separate residential units provide domestic hot water to the different users.
Scenario 2: Higher-temperature heat grid of 55°C: central heat pump supplies heat at 55°C, enabling both heating and domestic hot water to be supplied directly through from the heat grid to the various users.
The study showed that scenario 2 is the most ideal for both Ecopower as investor, developer and operator and for the residents of the mill site. The results of the analysis were put into a financial model, which showed that the project is not only practical and technical, but also financially feasible.
Ecopower was able to share this good news at the residents' meeting in Rotselaar at the end of January 2025.
Less is more
The major advantage of the second scenario - installing a 55°C heat network - is that no additional investments in individual booster heat pumps or other heating technologies in the housing units are needed. Current heating systems are not compatible with the 40°C heating temperature of scenario 1.
In Rotselaar, a very straightforward system will be developed, with the central heat pump providing sufficient high-temperature heat. Through the heat network, this heat will be distributed and used by the various residents for both central heating and domestic hot water.
Maximum use of the water turbine
One of the big advantages to the Rotselaar pilot site is the presence of the water turbine. The electricity generated by this is currently - besides feeding a car charging station - fully fed into the grid. The aquathermal heating project allows the electricity to be used locally by powering the central heat pump. The electricity supply to the heat pump will not go via the electricity grid but will come directly from the generator, so there are no grid charges.
The 55°C central heat pump - scenario 2 - covers the global heat demand (heating and domestic hot water). In this way, the coverage of the electricity from the turbine is maximised. A 40°C heat network - scenario 1 - always involves installing booster heat pumps in the individual residential units. These devices can not be powered by the turbine's electricity, but rather by the resident's own electricity connection. The heat supply itself would therefore be cheaper for the user itself in scenario 2. Moreover, then the heat demand is supplied entirely with green heat.
Opting for lower COP
When choosing scenario 2, the scenario with a lower COP or efficiency is chosen. With a 40°C heat pump, the heat pump delivers a lower temperature of heat, yielding a higher efficiency (COP) of the heat pump. However, this advantage for both Ecopower and mill residents does not outweigh the benefits of scenario 2 (such as cheaper heat supply, simpler system, 100% green).
50°C test
Meanwhile, a 50°C test was initiated among mill residents. In this test, the central heating systems at the residents' homes were set to 50°C, to check whether the current heating systems are compatible with lower-temperature heat supply via the heat pump. Although such a system provides slower heat delivery, all residents were still comfortably warm in winter temperatures. The conclusion is with scenario 2 - a 55°C heat network - Ecopower can obtain a sustainable and reliable heat supply for the entire mill site.
Positive business case for the Belgian pilot site
The figures were incorporated into a financial model, where the outcome turned out to be positive. With this, the pilot site in Rotselaar seems both practically, technically and financially feasible. Implementation in the summer of 2025 is approaching, ahead of schedule.