In 1839 Sir William Grove invented the fuel cell. He produced electricity by uniting H and O at electrodes that were separated by an aqueous liquid acid electrolyte. [ 1 ] Subsequently. throughout the 19th and twentieth centuries. a assortment of research workers investigated fuel cell reactions for the transition of chemical energy into electrical energy. [ 2 ] The first practical application of fuel cells occurred during the Apollo infinite plan from 1960 to 1965. [ 1 ] Those fuel cells provided both drinking H2O and electricity.
In 1970 Kordesch built a auto that operated utilizing the combination of an alkaline fuel cell and a lead acid battery. Recently environmental pollution issues have been the driving force for the development of fuel cells. [ 3 ] Fuel Cells – Definition. Composition. and Operating Principles A fuel cell is a device that generates electricity and produces heat from an electrochemical reaction utilizing suited accelerators. The most common fuel used in fuel cells is H. It is used in combination with O to bring forth electricity based on the following overall chemical reaction [ 4 ] :
H2 + 1/2 O2 & gt ; H2O In general. a fuel cell assembly can be divided into five beds as shown in figure 1. On each side of the five beds there are flow channels that are normally machined into solid black lead home bases. The anode side of the fuel cell includes the anode-backing bed ( anode diffusion bed ) and the anode accelerator bed. The cathode side includes the cathode endorsing bed ( cathode diffusion bed ) and the cathode accelerator bed. The electrolyte bed separates the anode side from the cathode side of the fuel cell.
If the electrolyte is a membrane. the five beds are called a Membrane Electrode Assembly ( MEA ) [ 5 ] . Hydrogen or a hydrocarbon-containing fuel such as methyl alcohol is supplied to the anode side and electrochemically oxidized. Oxygen or air is supplied to the cathode side and electrochemically reduced. The anode reaction that occurs at the anode side ( anode accelerator bed ) produces protons and negatrons. [ 6 ] Electrons flow through ( a ) the electronically carry oning anode stuff. to ( B ) the external circuit that contains an electrical burden. to ( c ) the cathode side.
The protons travel through a specific electrolyte ( such as a membrane ) . to ( d ) run into the negatrons and O at the cathode side. where the cathode reaction occurs [ 1 ] . Each of the fuel cell beds has single features. The backup beds in the anode and the cathode have several maps. They are the thickest of the beds and they provide the mechanical strength for the MEA that includes the other beds of the fuel cell. They are made from either carbon paper or C fabrics composed of fibres that create a porous construction.
The channels incorporating the flowing reactants are interspersed with “lands” . or parts of the backup beds that are non exposed to reactants. The porous constructions of the backup beds permit the reactants to spread in a way perpendicular to the accelerator beds and thereby supply a more even concentration of reactants at the interface between the accelerator bed and the backup bed [ 4 ] . The C backup beds besides provide both good electronic conduction for the negatrons that participate in the electrochemical reactions and good heat conduction for the heat released when the electrochemical reactions that occur.
Frequently the backup beds are made hydrophobic by utilizing Teflon. in order to avoid deluging that comes from H2O produced by the reaction. The demand for hydrophobicity at the cathode is by and large greater than that at the anode. as most of merchandise H2O is produced at the cathode [ 7 ] . The following bed is the anode or cathode accelerator bed that is a thin porous solid. It is frequently composed of a cherished metal ( Pt. Ru ) on a C support. The C support provides a big surface country on which the cherished metal can be dispersed. This permits a big surface country of the cherished metal to reach the reactants.
The last bed that separates the two sides is an electrolyte. The type of electrolyte is normally the characteristic that distinguishes the different fuel cell types. The intent of the electrolyte is to transport ionic species ( eg. H+ ) from one side to the other [ 1 ] . Advantages of Fuel Cell Compared to Combustion In rule fuel cells procedures can hold well greater energy efficiencies than burning procedures. During burning a fuel is burned in the presence of an oxygen-containing gas ( normally air ) to bring forth heat ( eg. firing gasolene inside the internal burning engine of a auto ) [ 2 ] .
The lastingness of stuffs at high temperatures limits the theoretical energy efficiencies of burning procedures to about 60 % . The energy efficiencies obtained in pattern are usually in the 30-40 % scope. In fuel cells. the fuel reacts electrochemically to bring forth electricity [ 8 ] . Fuel cells are non required to run at temperatures every bit high as those in burning procedures. In contrast to burning procedures. the theoretical energy efficiencies of fuel cells can be above 90 % . One of the ends of current fuel cell research is to show fuel cell energy efficiencies that exceed those of burning procedures [ 8 ] .