In-situ microwave heating-assisted coalbed methane extraction using hybrid photovoltaic-wind power: Performance analysis and system optimization

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This paper proposes a novel in-situ microwave heating technology for coalbed methane extraction integrated with a photovoltaic-wind hybrid microgrid, aiming to reduce the energy consumption and environmental impact associated with conventional mining methods. A multi-physics mathematical model encompassing electromagnetic fields, heat transfer, coal deformation, and gas seepage was established to simulate the dynamic coupling process during microwave-assisted methane extraction. The effects of microwave power and coal seam parameters—including thickness, initial permeability, and Langmuir coefficient—on methane desorption efficiency and system economics were systematically investigated. Results indicate that the microgrid configuration with solar power requires the lowest initial investment, and the overall economic performance of the system is optimized at a microwave power density of 1000 W/m. Microwave heating enhances methane desorption, increasing extraction efficiency by 30% compared to traditional methods. Economic analysis reveals that coal seam thickness and the Langmuir coefficient significantly influence system economics, whereas initial permeability has a minor effect. A combination of high permeability (4.5×10 -16 m 2 ) and high Langmuir coefficient (0.048 m 3 /kg) yields the lowest gas production cost (0.0549–0.2364 USD/m 3 ), which is substantially below China's natural gas market price (0.35 USD/m 3 ). Medium-thick coal bed demonstrate greater resilience to natural gas price fluctuations. The study confirms that the PV-wind microgrid effectively mitigates energy supply instability and enables low-cost, low-emission coalbed methane development.