Using industrial default values for prospective modeling of new materials production – the case of photon upconversion materials for solar modules

Conference poster, 2021

Several approaches to upscaling of materials production processes in the context of prospective life cycle assessment (LCA) have been proposed. Often, such approaches are bottom-up, departing from laboratory-scale descriptions of production processes and from that creating a model of future large-scale production. While such approaches make use of the material-specific knowledge available at the time of the assessment, they often neglect emergent aspects that may be present at factory level. An alternative, more top-down approach is to use industrial default values, i.e. average or typical values of inputs and outputs reflecting materials production today. Since production facilities normally do not change drastically over at least 10 years, such values might be relevant in prospective LCAs, at least given modest time horizons. Such default values can also be modified based on assumptions about future changes, such as increased energy recovery or novel solvent recovery processes. We applied previously derived industrial default values for fine chemical production when modeling the production of two materials with potential use in photon upconversion applications: lead sulfide (PbS) and lead selenide (PbSe) nanoparticles. Photon upconversion means that two low-energy photons are converted into one higher-energy photon utilizable by a solar module. While we used some material-specific values, such as synthesis-specific yields, most auxiliary input and output values (e.g. solvents, inert gas, heat, electricity and emissions) instead represent factory-scale values for current fine chemical production. Considering the availability of both best- and worst-case default values, it was possible to derive ranges for the likely future environmental impacts of the two materials. We conclude that the approach is feasible, but the availability of more up-to-date industrial default values would make it even more relevant in prospective LCAs.