Background Information
Our society is in constant of renewable energy sources that are sustainable and efficient. When most people think of ways to stop the impacts of fossil fuels and excessive carbon dioxide emissions they think of sources such as windmills, photovoltaic cells (solar cells), and hydroelectric energy. However, many people have not looked to using fuel cells in an efficient and sustainable way of combatting climate change. For example, the recent discovery of using hydrogen fuel cells in order to generate cars. One type of fuel cell that people have underestimated is the power of a microbial fuel cell (MFC). A microbial fuel cell relies primarily on the metabolism of bacteria and microbes in order to produce and electrical output. This fuel cell however has less efficiency as low as 40% to as high as 60% based on the amount of electrical potential it has. With ongoing research in the past decade researchers and scientists have tried to develop novel ways in order to increase the efficiency of the MFC and to find an application of the device. The objective of this research, however, is to determine if the addition of substrates and the type of metabolisms in bacterial isolates will have a substantial effect on the electrical output of an MFC and to see if MFC’s can have practical applications to the world.
​
The development of MFC’s comes from the principles and methods of other fuel cells. For one it has an anode and cathode and that they create electricity by spontaneous reactions (negative delta G) that convert chemical energy into electrical energy (Capodaglio, 2012). In MFC’s the chemical energy that is used is being created through the metabolism of electrogenic bacteria that shuttle electrons from the anode to the cathode creating a flow of electricity. Using this concept and methodology scientists have developed different types of microbial fuel cells. One type of MFC is a two chambered MFC where the bacteria catalyze the substrates through usually oxidation in the anode and transfer the electrons to the cathode where there are reduced by oxygen (Logan, 2006). Another type of MFC are mediator-less MFCs where bacteria transfer electrons to the electrode since the bacteria have motility and are active in creating electricity.
​
One problem of the creation of the MFC and its uses other than its efficiency is that many researcher have been using the same methods that cost a lot of money to create and have one of the lowest efficiency rates. This sparks a need for new and improved MFCs that have a better efficiency than previous fuel cells. This change in research made researchers develop better anodes in order to increase fuel cell electrical efficiency. This change also brought upon the idea of utilizing carbon nanotubes in order to increase the electrical efficiency of a fuel cell.
There are many current applications for MFCs one of them included in many scientific journals is the idea of wastewater treatment by using anaerobic digestion. Anaerobic digestion is possible since active anaerobic bacteria can be used which are found in mediator-less Microbial Fuel Cells. Anaerobic digestion works when microorganisms break down biodegradable materials in the absence of oxygen (National Non-Food Crops Centre, 2011). This principle can then be used in order to break down organic matter, in wastewater management, that would have been disposed into the sea. Another way anaerobic digestion could be used in is by using an anaerobic digester as a sanitation system while producing biogas for energy and fertilizer. Anaerobic digesters could reduce greenhouse gases by replacing fossil fuels and reducing the energy footprint of waste treatment plants (Zhang, 2013).