Poor data and outdated methods sabotage the decarbonization efforts of the chemical industry

High-quality data is a prerequisite for the sustainability assessment of chemicals. However, the most prevalent databases currently contain either intransparent aggregated data (impeding quality checks) or, in absence of measured data, rely on widespread use of proxy data for key inventory flows. This study analyzes the quality and implications of proxy data use for filling data gaps in the chemical sector of the ecoinvent database, the most commonly used database, that has found a broad range of applications in politics, industry and science. The individual datasets in that database are compared against simulation-based data as well as commercial chemical-sector data. The propagation of the proxy data in ecoinvent is traced along the complex chemical sector supply chains and consequences for carbon footprints and life cycle assessment (LCA) are calculated. The results demonstrate that due to the use of inappropriate proxy data, the heat demand of chemicals production is heavily underestimated, while the electricity demands tend to be overestimated. Environmental impacts such as the climate change impacts of the chemical sector are largely determined by heat demands, resulting in a massive 44% underestimation of climate change impacts of chemical production in ecoinvent in comparison to simulation-based data. Hence, the quality of chemical data does not live up to the importance of the topic of sustainable chemistry and may lead to widespread erroneous conclusions of policy-makers and industries. To allow for robust environmental assessments of chemicals and to provide reliable decision support, more attention needs to be paid to appropriate data collection of key inventory flows. It is therefore necessary that the use of unspecific proxy data in key data sources is reduced to an absolute minimum and that specific industry data is used whenever possible. Such data is partly available, but needs updates and expansions. Better proxy approaches than the existing ones can also contribute to a more precise picture of environmental impacts from the chemicals sector, but these approaches should only represent a last resort for processes and products without any alternatives.