Comparison of the Energy and Economic Efficiency of Demand-Driven and Linear Biogas Plant

The aim of the study was to conduct an energy and economic analysis of construction of a demand-driven biogas plant. Two capacity configurations, 0.249 MW and 0.499 MW, were analyzed using four demand-driven operating variants and a linear reference case. Revenues were calculated under the Feed-in Premium (FIP) system based on electricity prices on the Day-Ahead Market (DAM) in 2025. Among the analyzed variants, D4 was the most favorable, combining the predetermined curtailment schedule introduced by the recent amendment to the Polish Energy Law, with additional price-responsive operation during the remaining months. For D4, net present value (NPV) reached PLN 3.826 million, with an internal rate of return (IRR) of 12.87% and a discounted payback period (DPBP) of 9.93 years for the 0.249 MW configuration, and PLN 17.045 million, with an IRR of 20.61% and a DPBP of 6.21 years for the 0.499 MW configuration. Although D4 generated a higher NPV than the linear variants, its higher investment costs resulted in less favorable IRR and DPBP values. Increasing the reference price for demand-driven biogas plants to approximately 1100 PLN/MWh could reduce this profitability gap. An indicative comparison showed similar expenditure per unit of energy capacity for the additional infrastructure required for demand-driven operation and battery energy storage system (BESS); however differences between the technologies and the cost assumptions prevent a direct assessment of their economic competitiveness.