A group of scientists led by Italy’s Catholic University of the Sacred Heart has conducted a techno-economic optimization of an agrivoltaic-powered anaerobic digestion (AD) plant for biomethane production.
A multi-objective genetic algorithm (MOGA) coupled with a technique for order preference by similarity to ideal solution (TOPSIS) ranking methodology was developed to optimize economic performance and land utilization simultaneously.
“This study presents the first optimization framework integrating bifacial agrivoltaic (APV) systems with anaerobic digestion plants specifically designed for biomethane production,” corresponding author Amirhossein Nik Zad told pv magazine. “To our knowledge, no prior research has combined a multi-objective genetic algorithm with TOPSIS ranking methodology in this APV-biomethanation context.”
At the center of the optimization stands a mesophilic AD plant in Piacenza, Italy, which requires a constant temperature of 37 C. It takes feedstock material at an hourly rate of 4.75 tons, and produces 6,789 Nm³/day of biogas, of which about 3,680 Nm³ are biomethane (BioCH4). The total annual electricity demand is 1,011.8 MWh, with a peak requirement of 119 kW. The plant has a heat demand of 1,340 MWh, peaking in January with 179 kW.
“We analyzed eight scenarios, grouped into three primary scenarios (grid-connected bifacial APV systems) and five alternative scenarios: off-grid APVs, grid-only (without APV), and conventional (combined heat and power alone) configurations,” Nik Zad explained. “For the three primary scenarios, our framework simultaneously optimizes economic performance and land utilization. For the alternative scenarios, an analytical techno-economic evaluation was conducted to benchmark their performance against the optimized solutions.”
Scenario 1 included an APV system, a grid connection, and a boiler. In Scenario 2, the boiler was replaced with a ground-water heat pump (GWHP), while Scenario 3 replaced it with a combined heat and power unit (CHP). Scenario 4 used only a CHP; Scenario 5 combined a grid connection with a GWHP; and Scenario 6 paired a grid connection with a boiler. Scenario 7 included an APV system with a battery energy storage system (BESS) and a boiler, whereas Scenario 8 combined an APV system with a BESS and a GWHP.
In all scenarios that included an APV system, the solar panels were installed vertically and used either one-axis or two-axis tracking. When a CHP unit was used, it consumed 24.05% of the produced biogas.
“The most striking finding was the dramatic economic superiority of heat pump electrification over biogas combustion strategies. Groundwater heat pump configurations achieved up to 8.7 times higher net present value (NPV) compared to biogas boiler or CHP alternatives within our primary (optimized) scenarios,” Nik Zad said. “This occurs because electrifying thermal demands preserves biogas for upgrading to biomethane, which commands significantly higher market value than electricity in Italy, approximately 5.5 times the electricity purchase price.”
The research group also found that the optimized on-grid APV configuration combining 1-axis tracking with GWHP (scenario 2) achieves superior economic performance with an NPV of €2.88 million ($3.35 million), outperforming the conventional CHP baseline (scenario 4) by 4.1 times.
“Another interesting result was the consistent dominance of 1-axis tracking systems over both 2-axis and vertical configurations across all scenarios,” Nik Zad concluded. “Despite 2-axis systems capturing more energy, the additional capital and operational costs offset these gains. The 1-axis configuration consistently provided the optimal balance between energy yield and cost-effectiveness, suggesting it represents a mature technology ready for standardization and large-scale deployment in integrated agri-energy systems.”
The academics presented their research work in “Techno-economic optimization of agrivoltaic-powered anaerobic digestion plant for biomethane production,” published in Energy Conversion and Management. Scientists from Italy’s Catholic University of the Sacred Heart and Sweden’s Mälardalen University have participated in the study.
