Energy Harvesting Strategies for Plant Microbial Fuel Cells in Sustainable IoT Applications

Battery-free Internet of Things devices and sensors are gaining momentum, making energy harvesting an essential component of self-powered systems. Conventional energy harvesting techniques use well-established methods to track the maximum power point during conversion. This approach is not strictly applicable to emerging, more sustainable power sources like Plant Microbial Fuel Cells (PMFCs). This paper addresses the challenge of maximizing power and energy extraction from PMFCs without compromising long-term performance. Maximizing power is complicated by the slow dynamics of the cells and the vulnerability of the biofilm to excessive current extraction. In contrast, maximizing energy is facilitated by cell unloading periods, as constant loading can deteriorate their durability. Electrochemical impedance spectroscopy (EIS) conducted on the cell electrodes provides valuable feedback to determine the most appropriate loading strategy. This approach optimizes PMFC durability and peak power production, while opening up exciting prospects for bio-sensing applications.