Production of Electricity using Microbial Fuel Cells - Research Proposal Example

Production of Electri using Microbial Fuel Cells Introduction: We have reached a stage where the conventional sources of energy like fossil fuels have been depleted so much that the coming generations will not be able to harness any of it. Therefore, there is an urgent need to discover sustainable sources of energy that will not only help in reducing the carbon footprint but can also be replicated in the developing nations. A literature review on such alternative sources of energy revealed that microbial fuel cells, which employ microorganisms to biodegrade pollutants from the environment to generate electricity, are a novel method of reclaiming natural resources along with providing a new means of generating energy. The design study project will focus on screening microorganisms for their ability to generate electricity from synthetic industrial wastewater. The purpose of the experiment will be to popularize the inexpensive MFCs and show if scaled up, they can present a low-price energy source, which will at the same time be used for bioremediation of water resources polluted by effluents. Microbial fuel cells work on the principle that some microorganisms produce electricity while metabolizing wastewater for their sustenance. The MFC consists of a semi-permeable, cation exchange membrane that allows ions to pass through them but not the microbes; two electrodes, usually the cathode is made up of platinum and the anode is carbon graphite or carbon cloth. It is fitted by a wire to complete the external circuit (Microbial Fuel Cell, 2008). Wastewater is made to flow through the anaerobic compartment and the bacterial metabolic action on the wastewater allows electrons to become free and the cell starts conducting electricity. Aim: The aim of the design study is to screen various microorganisms for their potential to produce electricity from synthetic industrial wastewater. Hypothesis: The hypothesis is that some strains of bacteria exhibit greater coulombic efficiencies than others, depending on the substrates and their own metabolic pathways. The bacteria that the project will deal with are Shewanella oneidensis, Pseudomonas sp., Clostridium acetobutylicum, Saccharomyces cerevisiae and Escherichia coli. Methodology: Materials Microbial fuel cell, microbial strains of Shewanella oneidensis, Pseudomonas sp., Clostridium acetobutylicum, Saccharomyces cerevisiae and Escherichia coli, growth medium for the microbes, synthetic wastewater solution. MFC design The MFC provided by the lab is single- chamber, with Platinum coated graphite cathode and graphite rod for anode. The cation exchange membrane allows only the protons formed in the anode chamber to move across it and combine with electrons travelling via the external circuit, and oxygen to form water. Experiment The experiment requires the bacterial inoculum to be introduced in the synthetic wastewater sample, along with specific preferred substrates like starch, glucose, sucrose, lactate and molasses in moderate quantities to facilitate bacterial growth. The next step would include monitoring the power output of each bacterial strain after incubating the mixture for 24 hours. The purpose of the experiment is to screen for bacteria that are more adept at producing electricity from wastewater by comparing their power densities. The independent variables in the experiment are the five different strains of biocatalysts that will be tested for energy production. The dependent variable is the amount of voltage produced by the microbial fuel cell. It will be measured with a multimeter in voltage units. The control would be a voltmeter fitted to an MFC with glucose solution of the same strength as the others without any bacterial inoculation. Timeline Day 1: All the necessary materials including the bacterial culture, medium and electric components have to be gathered. The growth medium will have to be prepared for sub-culturing. The substrate composition will differ with organisms. For example, Clostridium will require starch, glucose, lactate and molasses, E.coli requires glucose and sucrose, Pseudomonas prefers glucose solution, Shewanella oneidensis require lactate and yeast needs glucose solution (Du, Li & Gu, 2007). Day 2: The solution and bacterial inoculation have to take place for the first strain of bacteria. Day 3: Data for current and potential has to be gathered for each strain with passing time. A spectrophotometer can be used to perform COD test using potassium dichromate in excess, as oxidising agent, and comparing a blank with the 24 hour- old bacterial solution, would help to analyse the amount of substrate that has been consumed during the process. Day 4-11: The previous steps repeated for each strain. Day 12-13: Previous steps repeated for control. Precaution: The strains should be activated sufficiently before conducting the experiment; otherwise, the conclusions may be erroneous. The readings will have to be taken thrice for concordant values. Flowchart: Steps to conduct an experiment to verify the coulombic efficiencies of five different strains of bacteria: According to Ohm’s law, power may be calculated as: P= I*V where, P= power in milliwatts; I is current in milliamps, V= potential in millivolts. Safety procedures: 1. The use of rubber gloves is a must when dealing with electrical circuits, carbon electrodes and microbial samples. 2. To avoid contamination of microbial samples, the inoculation preparation and introduction can be carried on in a laminar air flow chamber. 3. The readings will have to be taken three times to get concordant values. Allowance will have to be made for bacteria which may remain inactive in the broth. Ethical consideration: Although a point of contention may arise if people consider living organisms being used to promote digitization, the bigger question remains that it is in the larger public interest that such studies be promoted. Sustainable alternatives can reduce our dependence on fossil fuels, and support clean fuels and greener environment, as well as help reduce the pollutants already present in our atmosphere. Hence, the pros of MFCs far outweigh any other points of view (Buttermore, 2012). Discussions: It is fast becoming imperative to identify and facilitate energy production using non-conventional and renewable sources in order to sustain the growth and development in nations across the globe. Depleted quantities of fossil fuels and rising fuel prices has spurred scientists to look for alternate resources. Inventions like microbial fuel cells which harness microorganisms to bioremediate polluted resources and in turn, provide energy, have encouraged rapid studies in finding more economical and efficient designs. The aim of this project design is to help decide whether low-cost and easily available materials can be used to build an MFC which is equally or more cost effective than the typical MFCs; and if yes, whether this design can be replicated on a bigger scale and introduced in developing nations that may not have enough resources to buy large scale MFCs to fuel their energy requirements and help in bioremediation. Resources: 1. Buttermore, R. 2012. Microbial Fuel Cell: Improving Wastewater Treatment, [online]. Available at: < http://www.pitt.edu/~rwb31/trends.html> [Accessed 15 March 2013] 2. Du, Z., Li, H. & Gu, T., 2007. A state of the art review on microbial fuel cells: A promising technology for wastewater treatment and bioenergy. Biotechnology Advances 25 (2007) 464–482. [pdf] Available at: [Accessed 20 March 2013] 3. Frequently asked questions about MFCs [pdf]. Available at: [Accessed 14 March 2013]. 4. Microbial fuel cells. (2008). [online]Available at: [Accessed 14 March 2013] Read More