## 2 Ecological Impacts
Conducting an LCA provides a data-driven evaluation of the environmental impacts associated with using advanced and lightweight materials like novel aluminum alloys in PBF-LB/M [31]. Life cycle inventory data for PBF-LB/M components is typically derived from industrial printing practices or academic studies. [PERSON] et al. [32] estimate that the energy consumption of Al alloy AM technologies during the cradle-to-gate phase ranges from 73 to 94 MJ/kg, with associated CO2 emissions between 5.0 and 6.4 kg CO2/kg. Figure 3: Life cycle of a component produced by PBF-LB/M. However, these values can rise significantly, reaching 374 to 520 MJ/kg and 25.4 to 35.4 kg CO\({}_{2}\)/kg, depending on the electricity system utilized and its energy efficiency. [PERSON] et al. [33] proposed a comprehensive life cycle model for the production of components utilizing AlSi10 Mg powder. As depicted in Figure 4, the life cycle inventory data for the scenario involving the production of four impellers per build job via PBF-LB/M indicates a total energy consumption of 775.6 kWh per build. Across the manufacturing of 7360 components, the process generates a cumulative emission of 304,309 kg CO\({}_{2}\)-eq, corresponding to an average emission of 41.35 kg CO\({}_{2}\)-eq per component. [PERSON] et al. [34] compared the environmental impacts of aluminum parts produced by PBF-LB/M with traditional machining and forming processes. Utilizing LCA techniques, the study assesses each method in terms of material production, processing, and weight reduction potential. The findings reveal that PBF-LB/M offers a sustainable advantage primarily in scenarios involving high geometric complexity, significant weight reduction, or applications within transportation systems. [PERSON] et al. [35] investigate the influence of design choices on the environmental sustainability of PBF-LB/M processes, utilizing LCA techniques on a bearing bracket produced with AlSi10 Mg. Critical design elements, such as topological optimization and support structure configuration, significantly impact energy consumption and CO\({}_{2}\) emissions throughout the product life cycle. The study findings indicate that carefully optimized design can achieve substantial environmental benefits, particularly in the operational phase of lightweight components used in transportation applications. Together, LCA, the circular economy, and eco-design form a holistic framework that drives sustainable practices in AM processes. The circular economy provides an essential framework for minimizing waste and maximizing resource use by maintaining materials, products, and components in continuous cycles. Unlike the linear \"take, make, dispose\" model, the circular economy aims to \"close the loop\", enhancing resource productivity and reducing reliance on virgin materials. This approach emphasizes recycling, repurposing, and remanufacturing and supports sustainable production and consumption. Metals are particularly well-suited for advancing a circular economy, owing to their superior recyclability and potential for repeated reuse without significant degradation. In PBF-LB/M,  
Figure 4: Life cycle inventory and impact assessment of manufacturing impellers via PBF-LB/M (based on data in [33]). circular economy principles align closely with manufacturing needs, as they support the recovery, recycling, and reuse of metal powders. Unused or excess powder can be collected, refined, and reintegrated into production, creating closed-loop systems and promoting sustainable resource management [10,36]. Eco-design has emerged as a strategic approach to embedding sustainability at the design stage, maximizing environmental benefits early in product development. In PBF-LB/M, eco-design leverages the flexibility of technology design to create more sustainable components. The layer-by-layer fabrication inherent in PBF-LB/M enables complex geometries that conserve material without compromising performance, advancing eco-design objectives and reinforcing the shift toward sustainable manufacturing practices.