A fuzzy optimization model for planning integrated terrestrial carbon management networks

Biochar application and enhanced weathering are negative emission technologies (NETs) with the potential for large-scale deployment for the removal of CO₂ from the atmosphere. Biochar is a solid product of pyrolysis that can permanently store carbon when applied in soil due to its chemical recalcitrance. Enhanced weathering is based on the acceleration of the natural reaction of moisture, CO₂, and alkaline minerals. Both of these NETs rely on the application of pulverized material to different types of terrestrial sinks, which can include marginal and agricultural land. These two NETs can be used separately or concurrently, depending on local sink conditions. In some cases, simultaneous application of biochar and mineral powder to soil has the advantage of attaining additional beneficial effects of soil amendment. Although recent papers have reported the development of process integration models for optimizing carbon management networks based on either biochar application or enhanced weathering, none have reported models integrating these two NETs in the same system. To address this gap, a fuzzy mixed-integer linear programming model is developed that integrates biochar application and enhanced weathering for large-scale carbon sequestration. Fuzzy set theory provides a well-tested framework for integration of both subjectivity and uncertainty into mathematical programming. The model determines the optimal allocation of biochar and/or alkaline minerals from each source to each sink, while considering the application limits and CO₂ sequestration potential. An illustrative case study is solved that clearly demonstrates the application of the model. The case study shows interesting results that can guide how the full sustainable potential of these two technologies can be utilized in a carbon management network.