Potential primary energy and cost savings through industrial symbiosis: Aluminum chips-to-feedstock strategies for additive manufacturing

With global aluminum demand on the rise and the sector's high energy intensity, the development of energy and resource-efficient manufacturing strategies has become increasingly important. During aluminum production, a large portion of material is lost before reaching the final product, making near-100% material reuse a key objective. Conventional recycling methods, based on remelting, offer advantages over primary production in terms of energy savings; however, they still present significant limitations, particularly when dealing with machining waste such as chips, which are prone to oxidation and quality degradation. In this context, industrial symbiosis emerges as a promising approach, to reduce waste generation by promoting circular material flows within and across manufacturing systems. However, implementing such strategies poses several challenges, including the need to manage material quality and compatibility. This study presents a comprehensive environmental and economic model of the entire process chain, from material process scrap recovery to final component production. The analyses are applied to compare four manufacturing routes: subtractive manufacturing, WAAM-based production, and two industrial symbiosis configurations integrating a solid-state recycling process, namely Friction Stir Extrusion, to generate WAAM-based feedstock. The analysis demonstrates that symbiotic strategies can significantly reduce energy use, material consumption and resource depletion. However, further process optimization is required to fully unlock their cost-effectiveness and industrial scalability.