Prospective, Anticipatory and Ex-Ante – What’s the Difference? Sorting Out Concepts for Time-Related LCA

Other conference contribution, 2023

Most life cycle assessment (LCA) studies have considered technologies as they are at the time of the study, often in a mature state. Increasingly, LCA studies attempt to assess emerging technologies in imagined states at future points in time, often referred to as prospective, anticipatory or ex-ante. However, a clear distinction between these LCA types is lacking. We aim to sort these concepts into a typology of time-related LCAs, contributing to more purposeful methodological choices. Existing frameworks for time-realted LCA types were reviewed and typology consisting of three dimensions was found to capture the most important differences. The first dimension is real time, which captures the time difference between the functional unit and the LCA. If the technology is modelled at approximately the same time as when the LCA is conducted, it can be called contemporary LCA. If the technology is modelled at a future point in time relative to the analysis, it can be called prospective LCA, and retrospective LCA if it is modelled at a past point in time relative to the study. Dynamic LCA accounts for that a technology can be “stretched out” along the real time dimension. The second dimension is technology maturity, which can be measured by technology readiness levels (TRLs). Ex-ante LCA considers technologies that are immature at the time of the study but model them in a future when they are assumed to have become mature, and is thus a specific type of prospective LCA. In contrast, ex-post LCA refers to studies of technologies that have reached maturity at the time of the study. Anticipatory LCA is effectively similar to ex-ante LCA but also entails the inclusion of numerous stakeholders in shaping the LCA study. Lab-scale LCA is a contemporary LCA of an immature technology with the aim of suggesting improvements to technology developers. The third dimension is causality. Some LCA studies mainly consider causes of a functional unit, which is often referred to as attributional LCA. Other LCA studies mainly consider effects of a functional unit, which can be called consequential LCA. While the former can be said to look backwards in time, the latter can be said to look forward in time from the perspective of the functional unit. Both types can, however, be retrospective, contemporary, or prospective LCAs as defined above. It is also possible to consider different types of causality, which relate differently to real time and technology maturity.