Proof-of-concept for a novel application for in situ Microfluidic Benthic Microbial Fuel Cell device (MBMFC)

Abstract

Benthic Microbial Fuel Cells (BMFC) are an environmentally compatible, carbon-neutral energy resource that can operate in marine sediments and provide underwater power. BMFC performance is dependent on both biological factors and engineering materials and design. The biological component, being less predictable in nature, is typically controlled in laboratory settings to optimize fuel cell performance. However, this study seeks to improve the in situ performance of BMFC power production through augmenting engineering design factors. Decreasing the distance between the electrogenic bacteria and the capture electrode could be a solution to improve the BMFC performance for in situ anode devices. To evaluate this, a layered microfluidic elastomeric on quartz chip was fabricated to confine the bacteria within ~90 µm from the chrome microelectrode matrix patterned onto the chip’s quartz substrate. The device served as a Microfluidic Benthic anode connected with a carbon cloth cathode to form a Microfluidic Benthic Microbial Fuel Cell (MBMFC). The MBMFC units were placed in sediment under flow-through laboratory conditions and power generation was recorded. Typical membrane-less microbial fuel cells in flow-through seawater laboratories or in situ conditions, have power production ranges 3–40 mW/m2 with steady state power averaging 8–10 mW/m2. The results from these MBMFC devices demonstrated power density of 30–120 mW/m2 with steady state production levels 20–80 mW/m2. Conservatively that is 3 times higher than previously recorded BMFC units in sediments from San Diego Bay, and an 8-fold improvement in steady-state production. However, in consideration of the immediate ramp-up time and steady-state power production, it is a marked improvement to traditional in situ BMFC performance. This serves as a proof-of-concept for a scalable in situ microfluidic device that could serve as a future potential power source. The presented approach may offer a testing platform for further optimizations in MBMFC research and development.