Structure design and performance comparison of large-scale marine sediment microbial fuel cells in lab and real sea as power source to drive monitoring instruments for long-term work

An advanced large-scale frame of marine sediment microbial fuel cells (MSMFCs) is designed, and their electrochemical performance and driving instruments to work for long term are firstly compared in the lab and sea, respectively. Their open circuit voltages (OCV) reach 0.698 V (the MSMFC-lab, deployed in the lab) and 0.815 V (the MSMFC-sea, deployed in real sea), respectively. The output power of the MSMFC-sea (427 mW) is 1.14 times of the MSMFC-lab (375 mW). The TD (temperature-depth sensor, 6 V) powered by the MSMFC-sea can continuously operate for 17 months. The operation of the MSMFC-sea is not influenced by seawater temperature, keeping a stable output power (120 mW), which is much different from the MSMFC-lab. The TD powered by MSMFC-lab can only operate for 3 months, due to the low temperature in winter. To avoid the disturbance of benthonic animals in the top layer sediment on the seafloor, a special MSMFC-sea structure has been designed to embed its anode in inner depth. The mechanism of the differences between the two kinds of cells is primarily suggested, and it is firstly confirmed that the MSMFCs can be used as the continuous power source of the monitoring instruments on seafloor.