Climate neutrality and renewable energy expansion demand multifunctional materials capable of simultaneous carbon sequestration and electrochemical energy storage. Agricultural residue biochar offers dual-function potential, yet conventional pyrolysis does not systematically optimize competing objectives. This study presents a simulation-based computational framework integrating multi-output random forest surrogate modeling with differential evolution algorithms to identify Pareto-optimal process configurations balancing specific surface area, CO2 adsorption, electrochemical capacitance, and carbon stability. 800 parameter combinations were evaluated across pyrolysis temperature (400–900 °C), residence time (0.5–3.0 h), heating rate (5–50 °C min− 1), activation chemistry (KOH, <InlineEquation ID="IEq1"><EquationSource Format="TEX">\(\:{\text{H}}_{3}{\text{PO}}_{4}\)</EquationSource></InlineEquation>, <InlineEquation ID="IEq2"><EquationSource Format="TEX">\(\:{\text{ZnCl}}_{2}\)</EquationSource></InlineEquation>, NaOH), and five feedstock classes using calibrated response surfaces. The surrogate model achieved test-set <InlineEquation ID="IEq3"><EquationSource Format="TEX">\(\:{\text{R}}^{2}\)</EquationSource></InlineEquation> of 0.971 (RMSE = 48.06 m2 g− 1 for specific surface area and 0.942 (RMSE = 6.67 F g− 1 for specific capacitance on 160 independent samples; CO2 adsorption yielded <InlineEquation ID="IEq4"><EquationSource Format="TEX">\(\:{\text{R}}^{2}\)</EquationSource></InlineEquation> = 0.788, while carbon stability index showed moderate fidelity (<InlineEquation ID="IEq5"><EquationSource Format="TEX">\(\:{\text{R}}^{2}\)</EquationSource></InlineEquation> = 0.497, RMSE = 0.069), consistent with challenges in modeling recalcitrance from compositional proxies. Multi-objective optimization identified configurations with specific surface area of 1094 m2 g− 1, <InlineEquation ID="IEq6"><EquationSource Format="TEX">\(\:{\text{CO}}_{2}\)</EquationSource></InlineEquation> adsorption of 5.01 mmol g− 1, and specific capacitance of 114 F g−1. Pyrolysis temperature was the dominant predictor (48% feature importance); hydrogen-to-carbon ratios below 0.4 demarcate recalcitrant materials suitable for millennial-scale sequestration. Optimized processing achieved feedstock-independent carbon stability (median 0.44–0.46) across all biomass types. Spatially explicit assessment indicates that EU-scale deployment could sequester 53.9 Mt<InlineEquation ID="IEq7"><EquationSource Format="TEX">\(\:{\text{CO}}_{2}\)</EquationSource></InlineEquation>e year−1, equivalent to 1.2% of total EU greenhouse gas emissions. Experimental validation of selected configurations constitutes the primary direction for future work.

Computational framework for multi-objective optimization of activated biochar properties using machine learning and evolutionary algorithms

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2026年5月18日

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Mohammad Fazle Rabbi

摘要

Climate neutrality and renewable energy expansion demand multifunctional materials capable of simultaneous carbon sequestration and electrochemical energy storage. Agricultural residue biochar offers dual-function potential, yet conventional pyrolysis does not systematically optimize competing objectives. This study presents a simulation-based computational framework integrating multi-output random forest surrogate modeling with differential evolution algorithms to identify Pareto-optimal process configurations balancing specific surface area, CO₂ adsorption, electrochemical capacitance, and carbon stability. 800 parameter combinations were evaluated across pyrolysis temperature (400–900 °C), residence time (0.5–3.0 h), heating rate (5–50 °C min^− 1), activation chemistry (KOH, \(\:{\text{H}}_{3}{\text{PO}}_{4}\), \(\:{\text{ZnCl}}_{2}\), NaOH), and five feedstock classes using calibrated response surfaces. The surrogate model achieved test-set \(\:{\text{R}}^{2}\) of 0.971 (RMSE = 48.06 m² g^− 1 for specific surface area and 0.942 (RMSE = 6.67 F g^− 1 for specific capacitance on 160 independent samples; CO₂ adsorption yielded \(\:{\text{R}}^{2}\) = 0.788, while carbon stability index showed moderate fidelity (\(\:{\text{R}}^{2}\) = 0.497, RMSE = 0.069), consistent with challenges in modeling recalcitrance from compositional proxies. Multi-objective optimization identified configurations with specific surface area of 1094 m² g^− 1, \(\:{\text{CO}}_{2}\) adsorption of 5.01 mmol g^− 1, and specific capacitance of 114 F g⁻¹. Pyrolysis temperature was the dominant predictor (48% feature importance); hydrogen-to-carbon ratios below 0.4 demarcate recalcitrant materials suitable for millennial-scale sequestration. Optimized processing achieved feedstock-independent carbon stability (median 0.44–0.46) across all biomass types. Spatially explicit assessment indicates that EU-scale deployment could sequester 53.9 Mt\(\:{\text{CO}}_{2}\)e year⁻¹, equivalent to 1.2% of total EU greenhouse gas emissions. Experimental validation of selected configurations constitutes the primary direction for future work.