Life cycle assessment of carbon removal via enhanced weathering of mill ash and basalt on North Queensland farmlands, Australia - Thesis

[Geoengineering News]

https://dr.ntu.edu.sg/entities/publication/73833aa9-a714-4bc5-8112-8b760c367a19

Author(s): Xia, Jinyin

2026

Abstract

This study evaluates the carbon dioxide removal (CDR) potential of two enhanced weathering (EW) materials—basalt and mill ash—applied to farmlands across North Queensland, Australia, as part of a life cycle assessment (LCA) of global warming mitigation strategies. Both materials were applied at a one-off rate of 50 t/ha and assessed over a 15-year period. CDR efficiencies were quantified using high-resolution geochemical modeling developed by the James Cook University research team, then compared against transportation and field-application emissions to estimate net CDR potential. A key contribution of this work is the development of a comprehensive LCA for mill ash, a relatively underexplored EW material. Transport distances were derived from real-world Australian road networks using a spatial grid framework, enabling a more realistic representation of large-scale deployment. Spatial optimization was applied to exclude land unsuitable for EW application, reflecting practical deployment constraints. Results indicate that basalt achieves higher CDR efficiency and is less sensitive to soil conditions and transport distance than mill ash. Under the optimized scenario, basalt yields a net CDR of 20.0 × 10⁶ – 20.7 × 10⁶ tCO₂, compared to 2.61 × 10⁶ – 2.84 × 10⁶ tCO₂ for mill ash. Sensitivity analysis reveals that transport emissions are the dominant source of lifecycle carbon emissions. Estimated costs of 52.5–273.8 USD / tCO₂, combined with soil fertility co-benefits, suggest that both materials are competitive relative to other CDR approaches.

Source: Nanyang Technological University