Time-differentiating methods for life cycle assessment of the industry transition toward climate neutrality: A review

The industry transition toward climate neutrality requires manifold adaptations of present production processes, which include novel technologies using renewable energy carriers. The established method of life cycle assessment (LCA), designed to evaluate static processes, reaches its limits when applied to changing systems. We have conducted a systematic literature review on time-differentiating LCA methods for assessing transforming processes in their transition toward climate neutrality. On closer examination, three major types of dynamics emerge: transition dynamics, process dynamics, and dynamic impact assessment. Transition dynamics represent the gradual modification of the production. Process dynamics take into account the duration of processes and their temporal dependency on each other. Dynamic impact assessment demonstrates how the biosphere reacts to dynamic emissions. The reviewed literature delivered several examples of prospective LCA dealing with scenario integration or ex ante observations of emerging technologies. These typically differentiate only the transition temporally. By contrast, some methodology papers for dynamic LCA cover all three types of dynamics. Those comprise absolute changes and relative time dependence between processes, as well as metrics for the dynamic impact assessment of greenhouse gases. In conclusion, literature uses the terms dynamic and prospective LCA for overlapping research areas, both of which are highly relevant for evaluating a transforming system. However, methods are mostly applied separately in use cases also not related to an explicit decarbonization target. Aiming for harmonization of both concepts, we identified promising building blocks in a combined dynamic and prospective LCA to assess transition paths toward climate-neutral production.