Techno-economic optimization of agrivoltaic-powered anaerobic digestion plant for biomethane production

Decarbonizing biomethane facilities demands integrated electricity-heat strategies respecting land constraints. This study presents the first optimization framework integrating bifacial agrivoltaic systems with anaerobic digestion plants for biomethane production, addressing a critical gap in renewable energy system design. A multi-objective genetic algorithm coupled with Technique for Order Preference by Similarity to Ideal Solution ranking methodology was developed to simultaneously optimize economic performance and land utilization across three distinct agrivoltaic configurations including fixed vertical, 1-axis, and 2-axis tracking systems. The framework evaluates eight scenarios encompassing on-grid agrivoltaic systems with various heating technologies (biogas boilers, groundwater heat pumps, and biogas combined heat and power units), alongside benchmark alternatives including standalone combined heat and power unit (baseline), grid-dependent systems (without agrivoltaics), and off-grid agrivoltaic configurations. Results demonstrate that the on-grid 1-axis agrivoltaic system integrated with groundwater heat pump achieves superior techno-economic performance, delivering a net present value of 2.88 M, representing a 4.1-fold improvement over conventional combined heat and power baseline systems. This configuration maximizes biomethane sales by electrifying thermal demands, avoiding biogas combustion and capitalizing on favorable biomethane-to-electricity price ratios. Heat pump electrification strategies consistently outperform biogas-combustion strategies (boiler or combined heat and power) in net present value, achieving up to 8.7 times higher performance through strategic biogas preservation for upgrading within the primary scenarios. Comparative analysis confirms the superior techno-economic and spatial performance of optimized on-grid systems, with 9.17-11.23 M higher net present value and 17-20 times lower land occupation than off-grid alternatives. Sensitivity analysis confirms the consistent superiority of on-grid 1-axis agrivoltaic systems paired with heat pumps, reflecting robust trade-offs between energy yield, cost, and land priorities. The developed framework offers a versatile approach for integrating renewable energy in agricultural systems, promoting a sustainable energy transition while maintaining agricultural productivity.