Additive Manufacturing for Spare Parts Management: Is Decentralized Production Always Environmentally Preferable?

Additive manufacturing (AM) has emerged as a promising solution for spare parts management. Given the possibility of producing spare parts close to the point of use, the literature generally asserts that decentralized AM production is more environmentally friendly than centralized AM production. However, when asserting this, the literature overlooks AM's high energy intensity and variable CO2,eq emissions from electricity generation in different countries. The current study addresses this problem by analyzing when centralized AM production is environmentally preferable to decentralized AM production, taking a lifecycle perspective. A mathematical model quantifies CO2,eq emissions for both strategies and determines which is environmentally preferable, and a decision tree analysis is used to develop a decision tree that suggests when centralized AM production is environmentally preferable. Interestingly, our results contradict the current literature, showing how centralized AM production can be a more environmentally friendly strategy than decentralized AM production, especially in countries with low CO2,eq emissions. Adopting centralized AM production when preferable would result in significant reductions of CO2,eq emissions that, considering the current carbon reduction schemes recently introduced, would lead to substantial economic savings (even up to 3000 USD/year per spare part). Moreover, considering future trends in sustainable energy sources and AM technology advancements, this study explores how the preferable AM production strategy might evolve, showing that this does not greatly affect the convenience of centralized AM production. Finally, a practical application of the decision tree in two case studies demonstrates its utility for two companies and the potential savings achievable.