Using Microbial Fuel Cell to Test Energy Production of SCOBY Fermentation Microbes

By: Anh T.
Year: 2022
School: Westminster High
Grade: 11
Science Teacher: Huy Pham

To aid students suffering financially, schools in Orange County provide free lunches (HBUHSD…). As regulations require students to take a fruit, fruit waste increases compared to previous years. In the U.S. alone, “more than a third of edible food is tossed… happens most with fresh produce” (KCRW). As fruits are disposed in landfills, they decompose and release methane, covering 8% of the world’s emissions (KCRW) and 30% of total food waste generation (U.S. Environmental…).

This project tests the energy production during Kombucha fermentation through a microbial fuel cell, using SCOBY as the bacteria. SCOBY bacteria is considered harmless because it is mostly yeast.

As SCOBY feeds on the fruit waste’s sugar, they release electrons and generate an electric current (Ruscallelda Beylier) due to its exoelectrogenic bacteria and thus, reducing waste and greenhouse emissions to provide a renewable source of energy. Due to SCOBY’s biofilm regeneration, this process can be sustained for long periods of time.

The objectives were (1) finding the optimal amount of sugar and (2) generating the highest energy output with the hypothesis that an increase in the amount of sugar—independent variable— will encourage SCOBY fermentation and thus generate greater electricity —dependent variable.

To diverge away from fossil fuels and their harmful implications on the environment, this experiment strives to propose a novelty source of renewable energy, using the premise of microbial fuel cells (MFC) to generate electricity from Symbiotic Culture of Bacteria and Yeast (SCOBY) under the hypothesis that greater amounts of sugar —fruit waste— will result in greater energy produced. In a controlled school laboratory, the experiment begins with SCOBY fermentation on December 27, 2021, for 4-weeks. Medicine bottles were collected to build the MFCs sample groups with different amounts of sugar, conducting two trials over two weeks. The results yielded data that support the hypothesis as energy output increased in correlation to higher sugar concentrations and the T-test confirmed the relation between sugar and energy output. If replicated, experimental errors such as salt bridges, inconsistency in O2 level, and fruit mixtures would be resolved.