Methodological review and detailed guidance for the life cycle interpretation phase.

Life cycle interpretation is the fourth and last phase of life cycle assessment (LCA). Being a "pivot" phase linking all other phases and the conclusions and recommendations from an LCA study, it represents a challenging task for practitioners, who miss harmonized guidelines that are sufficiently complete, detailed, and practical to conduct its different steps effectively. Here, we aim to bridge this gap. We review available literature describing the life cycle interpretation phase, including standards, LCA books, technical reports, and relevant scientific literature. On this basis, we evaluate and clarify the definition and purposes of the interpretation phase and propose an array of methods supporting its conduct in LCA practice. The five steps of interpretation defined in ISO 14040-44 are proposed to be reorganized around a framework that offers a more pragmatic approach to interpretation. It orders the steps as follows: (i) completeness check, (ii) consistency check, (iii) sensitivity check, (iv) identification of significant issues, and (v) conclusions, limitations, and recommendations. We provide toolboxes, consisting of methods and procedures supporting the analyses, computations, points to evaluate or check, and reflective processes for each of these steps. All methods are succinctly discussed with relevant referencing for further details of their applications. This proposed framework, substantiated with the large variety of methods, is envisioned to help LCA practitioners increase the relevance of their interpretation and the soundness of their conclusions and recommendations. It is a first step toward a more comprehensive and harmonized LCA practice to improve the reliability and credibility of LCA studies.

From Laboratory to Industrial Scale: A Prospective LCA for Electrochemical Reduction of CO2 to Formic Acid.

CO2-based production technologies unveil the possibility of sustainable production in the chemical industry. However, so-called carbon capture and utilization (CCU) options do not inevitably lead to improved environmental performance, which is especially uncertain for emerging technologies compared to present production practices. Thus, far, emerging CCU technologies have been environmentally assessed with conventional life cycle assessment (LCA). Therefore, this study aims to develop a methodology for applying prospective LCA to emerging production technologies from the laboratory to industrial scale. The developed four-step approach for implementing prospective LCA is applied to the case of electrochemical formic acid (FA) production via supercritical CO2 (scCO2) under consideration of different reactor designs to guide process engineers from an environmental standpoint. While using prospective LCA, the underlying modeling approach relies on consequential LCA (cLCA). Fourteen out of the 15 analyzed impact categories (IC) reveal lower environmental impacts for the scale-ups, which are based on the best-case assumptions and on a flow-through regime compared to the conventional FA production. Nevertheless, the impacts of the scale-ups that are based on a batch reactor (BR) and a three compartment cell (TCC) are higher than for the best case and the flow-through reactor scale-up.