Grid Integration of Livestock Biogas Using Self-Excited Induction Generator and Spark-Ignition Engine to support the BCG model in Thailand

Abstract

This study aims to develop small grid-connected power generation units for farming systems to support Thailand's Bio-Circular-Green Economic Model (BCG). The focus is on utilizing agricultural waste resources within the circular economy framework of the BCG model. Biogas is used as the primary fuel for the internal combustion engine (IC engine), with gasoline and LPG as backup fuels for emergencies. The system includes an engine that drives a self-excited induction generator (SEIG). A grid-connected inverter control strategy based on PQ control has been designed for power conversion, using digital signal processing (DSP). Additionally, interface-based Internet of Things (IoT) devices enable wireless connectivity for monitoring and controlling the system via a dashboard application. The proposed system is validated with biogas produced from pig manure at a farm in central Thailand, achieving a maximum output of 1.2 kW with a thermal system efficiency of 10.7%. Scheduled operation at 1.2 kW for 8 hours daily yields a levelized cost of 0.07 US$/kWh, representing a 42% cost reduction compared to retail electricity prices, with a payback period of 2.76 years. The system is deemed suitable for farms with a minimum of 34 pigs, offering a sustainable and economically viable energy solution for rural communities.

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