Microbial_Based_Biofuel_Cell update 04_7_10

Microbial_Based_Biofuel_Cell update 04_7_10 - Presented to...

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Presented to : Prof. Evgeny Katz Name : Mahmud Diab I.D : 066589607
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Introduction Recent research on world-wide energy consumption predicts that by the year 2030 our energy consumption will have increased by 50%. Scientists are also becoming more aware of the transient nature of nonrenewable resources and their grave environmental hazards and risks (1). In addition, there is also a trend towards the miniaturization of electronic devices, including implantable devices such as pacemakers. Smaller devices require a small energy source and implanted devices require an energy source that is able to provide energy for long periods of time. Our dream is to be able to use substances found in the body as a fuel (i.e. glucose from the blood stream) to power the implanted devices. Biofuel cells could provide a solution to many of these problems, by generating electricity from available substrates (renewable sources) and powering small implanted devices. Biofuel cells use biocatalysts in order to convert the energy from chemical form to electrical form at two electrode interfaces (2-3). Oxidation processes occur at the anode (i.e. oxidation of methanol, organic acids, or glucose) and reduction processes occur at the cathode (i.e. reduction of O 2 or H 2 O 2 to H 2 O). A few important equations are necessary for describing the performance of a fuel cell are as follows: cell cell cell I V P × = (1) η - - = fuel OX cell o E a E V ) ' ( ) ( (2) Where P cell is the overall power generated by the fuel cell, V cell is the operating voltage, I cell is the cell current, E(a) OX is the potential of the oxidation reaction, E(o’) fuel is the potential of the reduction reaction, and η represents irreversible losses in the voltage as a result of kinetic limitations, electron transfer processes, ohmic resistances and concentration gradients. The current in the fuel cell can be controlled by changing the sizes of the electrodes or improving the ion permeability and transport rates across the membrane. The voltage can be controlled by choosing the electrode material and the fuel and oxidant sources. Thus, in order to maximize the power of the cell we need to optimize both the V cell and I cell values.
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Microbial Based Biofuel cells A microbial based biofuel cell relies on the use of microorganisms, either to generate the fuel or as catalysts for the oxidation and reduction reactions in the fuel cell. When microorganisms are used in biofuel cells, the need for isolation of individual enzymes is eliminated, simplifying our overall process. In order to achieve high efficiencies in our biofuel cells, we need to work under conditions that are similar to the natural environment of the biomaterials being used. There are two distinct challenges here. The first is that special conditions must be maintained in order to keep the microorganisms alive and the second is how to best connect these organisms to an electrode. Here, we will discuss three of the main approaches to designing microbial biofuel cells.
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This note was uploaded on 12/08/2010 for the course CHEMISTRY PYSICAL CH taught by Professor Dinur during the Spring '09 term at Ben-Gurion University.

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Microbial_Based_Biofuel_Cell update 04_7_10 - Presented to...

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