Development of life cycle assessment of an emerging technology at research and development stage: A case study on single-wall carbon nanotube produced by super growth method

The frontier of lifecycle assessment (LCA) case studies has moved from understanding conventional technologies to analyzing emerging technologies at the research and development (R&D) phase. One new challenge in LCA that aims to deal with this phenomenon is the development of methods to estimate the environmental impacts of emerging technologies in the R&D phase while considering manufacturing at scale. This study proposes a simple and feasible method that allows LCA practitioners to consider scaling effects of energy consumption during production in a case study of the super growth method of producing carbon nanotubes. In this case, the greenhouse gas (GHG) impact of producing 1 kg of carbon nanotubes decreases from 47.05 t-CO2eq to 21.33 t-CO2eq by scaling up the process. Although the total GHG impacts at the commercial scale estimated from the lab scale inventory are similar to those estimated from the pilot scale inventory, the share of GHG emissions of materials are different because of a change in substrate and a change from batch processing to continuous processing. Carbon nanotube production by the super growth method is competitive with those made by other processes from the viewpoint of GHG impact and product quality. •LCA framework considering upscaling of process is developed.•47 t-CO2eq of carbon nanotubes decreases to under 21 t-CO2eq by upscaling.•GHG impact changes by upscaling method of direct or indirect method.•GHG impact and their distribution differ by the phases of technology.