A Novel Approach in Redesigning Microbial Fuel Cells to Increase Practical Applications

Overview

With the rapidly increasing population, a stable yet clean energy source is needed. The Microbial Fuel Cell (MFC), a device that converts organic material into renewable energy using bacteria, is a promising solution to this problem. However, as MFCs are still undergoing research, current production costs surpass energy efficiency. Thus, the project’s goal was to design and test more efficient, cost-effective MFCs to determine the effect of the reactor type on power generation. Two novel MFC reactors- Single-chambered with Inner Cathode (SCIC) and Tubular MFCs- were designed and compared to the H-type MFC, the control used for basic parameter research. It was hypothesized that if the H-type, SCIC, and Tubular MFCs were tested, then the Tubular MFC would have the highest voltage, current, and power, as the Tubular MFC’s design of layered components would increase salt bridge surface area, reduce electrode distance, and decrease reactor size-thereby increasing proton and electron flow while decreasing internal resistance. The MFCs were built with graphite rods as electrodes, a salt bridge to facilitate proton flow, and wastewater as the source of bacteria. The H-type MFC was built using an exterior salt bridge to connect an anodic, anaerobic chamber and a cathodic, aerobic one. The SCIC consisted of an interior salt bridge with the cathode inside of it. The Tubular MFC was built using a cylindrical container with its components organized in layers. The outermost layer was the cathode, the second layer was the salt bridge, and the center held the wastewater and anode. The MFCs were connected to a multimeter, and voltage and amperage were recorded every 30 minutes for 3.5 hours. Data from four repeated trials was normalized to the total electrode surface area. The hypothesis was proven correct; it was found that the Tubular MFC performed the best, with both voltage and amperage increasing as time passed. Its voltage peaked at 3.5 hours with 11.46mV/cm2, while the H-type and SCIC MFC’s highest readings were 7.66mV/cm2 and 8.25mV/cm2. The greatest increase in voltage from the H-type MFC for the Tubular MFC was a 94% increase at 2 hours. The Tubular MFC also had the highest amperage of with 0.0068mA/cm2, followed by the SCIC with 0.0018mA/cm2. The power was calculated, and it was found that the Tubular MFC had the highest wattage of 4.58mW/cm2, followed by the SCIC MFC with 0.42mW/cm2. The Tubular MFC’s greatest increase from the H-type MFC was 76 times the wattage of the H-type MFC, which only generated 0.23mW/cm2. The total cost of the Tubular MFC’s was calculated to be $13.00. With power generation proportional to electrode surface area, the Tubular MFC’s peak power generation was extrapolated to be 45.8W/m2 at 3.5 hours. Therefore, power generation using the Tubular MFC for 1W/m2 was approximated to cost $0.28. Future studies include designing a self-sustaining MFC for wastewater and oil spill treatment.

Competition history

• AJAS 2018 Category not listed

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