A Study on the Renewable Power Generation Capacity of Microalgae Microbial Fuel Cells for Powering Giot Sensor Nodes

Microalgae-Microbial Fuel Cell (mMFC) is a novel and attractive green renewable energy source for bio-electricity generation. Its capacity to generate energy is of particular interest for the design of sustainable green internet of things (GIoT) sensor networks. However, this capacity needs to be assessed due to critical limitations in their low-level output voltage and possible bioelectrochemical disturbances. This study investigates the renewable energy generation capacity of an mMFC-harvester system for powering low-power wireless sensor nodes. A two-chamber mMFC prototype is designed as a proof of concept using the CMI7000 membrane and the BQ25570 circuit to harvest the energy. A sensor node based on Nordic nRF52840 ultra-low-power microcontroller implements a uniform power management strategy and the energy capacity is analyzed in terms of the number of Bluetooth low energy (BLE) transmissions. Experimental results show that after an initial cold-start period in the harvester circuit, the system stores the energy in a 0.1 F supercapacitor in 6.25 h, representing 3.26 J. The maximum power density generation is 80.10 mW/m2, and the energy harvested is suitable to perform up to 9 continuous transmissions using BLE.