Modeling of CH₄ Emission and Assessment of Energy Potential: A Case Study of Okhla Landfill, South Delhi

Municipal solid waste (MSW) landfills are major sources of greenhouse gas (GHG) emissions, particularly methane (CH₄), which possesses a significantly higher global warming potential than carbon dioxide (CO₂). This study evaluates methane emission and energy recovery potential from the Okhla landfill site, South Delhi, India, using the Landfill Gas Emissions Model (LandGEM). Site-specific model parameters suitable for Indian landfill conditions (k = 0.032 year⁻¹ and L₀ = 70 m³ Mg⁻¹) were incorporated to improve prediction accuracy. The results showed that methane generation initiated in 1997 and is expected to continue until 2068. Peak methane emission of approximately 17.15 million m³ year⁻¹ was observed in 2020 due to rapid degradation of the biodegradable organic fraction, especially food waste. The corresponding peak total landfill gas (LFG) and CO₂ emissions were approximately 35.43 million m³ year⁻¹ and 17.71 million m³ year⁻¹, respectively. A strong correlation (R² = 0.9557) between cumulative waste deposition and methane generation confirmed model reliability. The estimated maximum energy recovery potential was approximately 46.19 million kWh year⁻¹. The study further discusses the applicability of the LandGEM under non-engineered landfill conditions commonly observed in developing countries. Overall, the findings emphasize the importance of methane recovery for greenhouse gas mitigation, sustainable waste management, and renewable energy generation in urban landfill systems.