# Additive Manufacturing and Chemical Engineering: Looking for Synergies from a Bibliometric Study
## 4 Review of Research Focused on Additive Manufacturing and Chemical Engineering
### Additive Manufacturing and Chemical Engineering: Future Needs
#### 4.2.1 Additive Manufacturing and Life Cycle Assessment  
In its ongoing pursuit of more suitable processes, chemical engineering can utilize life cycle analysis to assess and enhance the sustainability of additive manufacturing. At each stage of the life cycle of a product obtained by additive manufacturing, resources such as raw materials, energy, and other consumables (compressed air, inert gas, refrigerants, etc.) are consumed, leading to waste generation and environmental emissions. Life cycle assessment is a widely recognized and internationally standardized methodology (ISO 14040) used to calculate the environmental impacts of a product or process across its various life cycle stages (Figure 13). Figure 13: Lifecycle of a product obtained by additive manufacturing (adapted from [117]). The specific evidence on how the existing applications of different additive manufacturing technologies promote the circular economy transition has been exposed [118; 119; 120; 121; 122]. Additive manufacturing has the potential to greatly impact supply chains in a number of positive ways, including increased responsiveness to changing demands, shorter production lead times, lower material usage and waste, customizability, localized production, energy efficiency, and reduced emissions [123]. Some additive manufacturing processes have the potential to close supply chain processes by repairing and remanufacturing in situ defective objects, thereby significantly reducing environmental impacts [124; 125]. For instance, an automated laser cladding system was designed to repair worn-out parts assisted by 3D scanning technology [126]. The validation results demonstrated that the streamlined process can reduce the processing time even for high-complexity geometries and at the same time build toolpath strategies taking into consideration process-specific needs such as dimensional accuracy. Furthermore, additive manufacturing is highly resource-efficient, decreasing the required amounts of raw materials when compared to traditional manufacturing [127]. This efficiency in material use is particularly relevant in reducing material waste, a key aspect of sustainability in manufacturing. However, it is important to note that material efficiency does not automatically guarantee a more sustainable process or product. Although additive manufacturing offers significant environmental advantages such as reduced material waste, other aspects like energy consumption and the quality of the final product must be carefully evaluated. For instance, the specific energy consumption of additive manufacturing processes can be 10 to 100 times higher than that of conventional molding and machining processes [128]. Additionally, achieving the desired dimensional accuracy and surface finish of products obtained by additive manufacturing may require post-processing operations such as final machining and heat treatments, which imply additional raw materials and energy consumption [129]. Assessing the energy consumption and environmental impact of the raw materials used in additive manufacturing is essential. A review of the literature reveals that energy consumption is the most studied aspect of the environmental efficiency of additive manufacturing processes, comprising 87% of the articles. However, only 25% of the studies employed life cycle assessment at some level [130]. Furthermore, it has been observed that energy consumption is the primary contributor to the global warming potential of additive manufacturing processes, whereas in conventional manufacturing processes, raw materials are the main source of this type of emissions. Accordingly, this finding highlighted the necessity for enhanced energy efficiency in additive manufacturing processes to boost competitiveness from an environmental perspective [131]. However, other pertinent factors, such as material inputs, inert gases, material waste, and the energy required for post-processing operations, must be taken into account.