Difference between revisions of "Team:Reading/FuelCell"

Fuel Cell

A major aspect of our project is of course the design and production of the fuel cell itself. We set out to design our fuel cell with three important properties in mind; efficiency, complexity, and cost.
We designed our fuel cells design to:

• Facilitate greater voltage output from the bacteria
• Be simple and easy to set up and maintain
• Be cheap to manufacture and require little expertise
• Be easily affordable to the poorest of communities
• Safely house the bacteria

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Background

The main source of electricity for the longest time has been through batteries, first invented by Alessandro Volta in 1800, and then through generators which used steam or momentum to power turbines. The batteries relied upon an electrochemical reaction between two electrodes to create an electrical charge which could be passed through an external circuit. But this had an issue in that the batteries would eventually cease production of charge as the ions of the two electrodes were depleted. Rechargeable batteries were eventually designed like the small lithium ion batteries seen in circulation and the lead acid batteries used in car, however these would still eventually wear out due to the constant usage.

In the 1970’s research gained traction in developing fuel cell technology. Fuel cells work by providing an environment where once fuel is introduced chemical reactions can take place causing electrons to flow through an external system back into the cell producing a by-product and charge. The most prevalent example of this is the hydrogen fuel cell currently used in hybrid and zero-carbon cars and buses, hydrogen and oxygen are the fuel which creates electricity and water as the main by-products. Hydrogen atoms are sent to a platinum catalyst at the anode where they are stripped of their electron then; passing through an electrolyte, move to be then combined with electrons and oxygen at the cathode to form water. The electron once freed from its proton flows through an external circuit where it powers a device, then flows on to the cathode.

Also in the 1970s research on microbial fuel cells (MFCs) began focusing on two main areas, mediator based MFCs and mediator-less MFCs. Mediator-less MFCs rely on electron transport complexes, such as cytochromes, on the outer membrane of the bacteria releasing electron on to the anode. Mediator based MFCs are much more efficient at producing charge however the mediators used are often expensive, difficult to maintain and can be toxic to the microbe that is being used. MFCs rely on different combinations of heterotroph or autotroph: a singular species of heterotroph, singular species of autotroph, multiple species of heterotrophs, multiple species of autotrophs, mixture of multiple hetero and autotrophs, and even plant involvement. The wastewater industry has found MFCs to be useful in removing compounds and halving power usage of the treatment process.

Biological Photovoltaics (BVP) are a type of MFC where only oxygenic photoautotrophic bacterial species are used, such as Synechocystis sp. PCC 6803, earning them the moniker “Living solar cells”. Unlike in a Heterotroph based MFC where the electrons would solely come from the electron transport chain (ETC), in BPVs the electrons can be lost from both the ETC and the thylakoid membrane. Furthermore unlike inorganic photovoltaics BPVs continue producing electricity in the dark phase as the bacteria are still respiring, providing a possible avenue into 24 hour solar based energy. However the research into this untapped source is ongoing since current BPVs cannot compete with the energy output of conventional photovoltaics despite the environmental advantages of such a system.

Design

Design of our fuel cell

Our Fuel Cell

final product, outputs, etc

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Large scale application of our design

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References