Improving life cycle assessment for carbon capture and circular product systems

PurposeThis research aims to critically assess the suitability of current ISO life cycle assessment standards and practices for the challenges of decarbonisation through the use of carbon capture and the circular economy. Currently, the handling of wastes, including carbon dioxide, in life cycle assessment varies from sector to sector. We propose several methodological innovations to improve transparency and comparability of life cycle assessments to aid in the decarbonisation transition.MethodsThree approaches have been used to analyse the shortcomings of life cycle assessment for carbon capture and circular practices: Recent standards and practices have been assessed to determine their suitability for decarbonisation; Life cycle assessment and industry experts were consulted through a workshop held at the University of Bath in September of 2022; Case studies of industrial decarbonisation projects funded by IDRIC have been conducted to apply solutions to the shortcomings identified through the former methods. The issues identified have been categorised into three key areas: (i) guidelines and standards; (i) temporal and regional issues and (iii) data quality analysis.Results and discussionThe methods of handling carbon capture, waste valorisation and circular practices were found to vary significantly from sector to sector. Temporal aspects are frequently aggregated in a specific point of time, leading to low resolution by neglecting emissions over the duration of the process that creates them. Regionalisation was found to be hampered by regional characterisation factors being representative of larger regions but unsuitable at county or state scale. Uncertainty and sensitivity analyses, which are key to assessing the validity of the impacts of new and emerging technologies, were found to be neglected or only partially conducted.Conclusions and recommendationsThe ISO life cycle assessment standards require updating to provide consistency in methodologies to make them suitable for use with carbon capture and circular systems and to avoid ambiguity. We recommend that the life cycle assessment community focuses on developing more consistent standards and practices between sectors to address carbon capture and circularity; improving the implementation of temporal aspects of impacts; increasing the number of studies including uncertainty and sensitivity analyses and moving towards global uncertainty in favour of local sensitivity.