Abstract for: Supporting the design of a circular factory with system dynamics simulation

A new startup in the Netherlands aims to process food waste from retail stores into animal feed. In order to convince investors, suppliers (and themselves), they want to find out whether or not they can create an efficient, yet robust factory, even if supply volumes and quality are changing over time. Together with their design team, we created a system dynamics model of the factory they have in mind. We started with a high-level model of the ideas they had in mind, quickly identifying that this wouldn't come close to the desired yield. Then we started improving the design together. The initial design of the factory would lead to a yield of roughly 30%. By increasing the number of working days per week, changing the prioritization logic for the mix tanks, adding recipes, increasing the capacity of specific installations, and allowing for expedition with smaller trucks, we were capable of increasing the yield to 71-78%. In addition, conservation of finished products and alignment results in vastly reduced operational costs. From a modeler's perspective, the key challenge in such a design process is to manage the degrees of freedom and constantly changing ideas. While it can be frustrating at times, we also experienced that the simulation process and model can be very helpful in a design process. It increased their understanding of the effects of design choices and enabled them to spend more time on critical parts of the design.