Enhancing sustainability in greenhouse agriculture through chemical analysis–driven characterization of boiler biogas fuel strategies

Greenhouses can enhance sustainability and productivity by integrating renewable energy and CO 2 enrichment, which improves photosynthesis and reduces environmental impact. However, existing studies on biogas and methane combustion have not addressed how combustion-derived CO 2 can be strategically managed to meet the coupled thermal and photosynthetic demands of greenhouse crops. In this context, the present study is the first to conduct a parametric analysis of biogas utilization for greenhouse applications, offering a proposed adaptive fuel management strategy hypothesized to support both environmental and economic benefits. To achieve this, a counterflow flame configuration is employed to investigate the combustion characteristics of a greenhouse boiler operating with various methane–biogas fuel mixtures. The detailed Gas Research Institute Mechanism (GRI-Mech 3.0), comprising 53 species and 325 reactions, is utilized to model the reaction kinetics. Detailed thermophysical and transport properties based on fundamental thermodynamics are integrated to accurately capture flame structure and species transport. The model was validated against experimental methane/air flame data, demonstrating good agreement and confirming its predictive accuracy. The effects of (1) CO 2 enrichment, (2) operating pressure, and (3) strain rate on flame temperature and species concentrations (CO 2 , CO, NO, and NO 2 ) are systematically investigated. Findings demonstrate the potential of biogas as a sustainable fuel under characterized conditions: Biogas substitution lowers peak in-flame NO x and CO concentrations while increasing peak CO 2 concentration, highlighting its potential for CO 2 enrichment. A pressure-sensitivity analysis (1–10 atm) and a proposed adaptive diurnal fuel-switching strategy are also presented. Practical guidelines are proposed to support greenhouse growers in enhancing thermal efficiency and environmental performance.