Process-based life cycle assessment of waste clay for mineral carbonation and enhanced weathering: A case study for northeast England, UK

The potential of enhanced silicate rock weathering for long-term carbon dioxide sequestration is substantial, but it is dependent on the availability of suitable materials and proximity to appropriate field application locations. This paper evaluates the implementation of waste clay in the form of filter cake on agricultural land in northeast (NE) England for mineral carbonation (MC) and enhanced weathering (EW) over 26 years from 2024 to 2050. Process-based life cycle assessment (LCA) is used in this study to provide an effective evaluation of CO2 emissions. Our results show that the potential levels of CO2 sequestration of filter cake through MC and EW are 0.16t CO2eq/t and 0.29t CO2eq/t respectively. Considering the sequestration potential of 580,000 ha of agricultural land in the NE England, it is shown that the deployment of waste clay in the form of filter cake on that land could capture 0.77 to 1.62 Mt CO2eq with an application rate of 11.2 t/ha for MC and EW respectively, while the corresponding CO2 emissions throughout the application of the processes involved are calculated to be only 0.27 Mt CO2eq over 26 years. This study demonstrates the importance of waste clay valorisation on agricultural soil in NE England in reducing CO2 in the atmosphere and its role in the UK's 'Net Zero' ambition.