Macro-level economic and environmental sustainability of negative emission technologies; Case study of crushed silicate production for enhanced weathering

Enhanced weathering (EW) involves application of crushed silicate rocks on croplands to capture CO2. Although research on EW is gaining traction, the missing elements in the literature however are the supply chain sustainability impacts associated with large-scale production and deployment of crushed silicates for EW purposes. The need to conduct sustainability assessments for EW systems in addition to validated technical feasibility remains a relevant research gap. In this work, the potential economic and environmental impacts associated with production of crushed silicates is assessed for eight countries, belonging to two separate groups: emerging economies (Brazil, Russia, India, and China) and developed economies (USA, UK, France, and Germany). A total of six economic and environmental impact categories are included in the assessment; gross domestic product (GDP), gross operating surplus (GOS), imports, greenhouse gas emissions, energy, and material use. The input-output model is used to estimate the economy-wide and macro-level sustainability impacts derived from producing crushed silicates. Findings show developed economies have relatively high levels of positive economic benefits and may experience less negative environmental impacts within their national boundaries by 'leaking' such impacts via imports. Imported consumption for crushed silicate production in developed countries were found to be substantially higher than that of emerging economies. For the emerging economies, imported consumption associated with crushed silicate production constitutes on average, less than 10% whereas for developed economies, imported consumption averages 20%. The UK mining and quarrying sector has the highest imported consumption at approximately 30%. The results of the study provide insightful outlook into the opportunities and challenges surrounding EW sustainability and is important in informing both national and global policy decisions regarding this technique.