An electro chemical cell is usually termed as fuel cells. Fuel cells are those which are dependent on the fuel for working. Electro chemical cells are those which derive their energy from chemical reactions or merely you can say they are dependent on the chemical reaction to take place. Christian Friedrich Schönbein was the first German scientist who introduced the concept of fuel cells for the first time in year 1838. The chemical reaction taking place in the fuel cells is supported by electrodes and a fuel tank. fuel cells come under the head of renewable energy forms due to the presence of hydrogen.
This reaction takes place between the anode and cathode, the fuel on one side and oxidant on the other side respectively. Anode is the side from where the current moves in, while the cathode is the side from where the current flows out. The reactant that is the fuel flows in and the reacting product flows out, however the electrolyte retains its position. Fuel cells keep working until the reactant flows in. fuel cells are a little different from the other batteries, because they constantly need flow of fluid from some external source. Fuel cells usually use many combinations of fuel and the oxidants. One of the most common combinations is the hydrogen fuel whose possible reactant is the oxygen present in the air. The chemical reaction in the fuel cells is dependent on the catalyst.
Catalyst is the substance which helps the chemical reaction to increase or decrease speed. In this chemical reaction the electrons and the protons get separated. The electrons and the protons travel in the circuit, thus an electric current is generated. The catalyst used in this chemical reaction is the platinum plate. Another catalysis also produces waste or by product in the process. This by product can be water in some cases. 0.6 to 0.7 volts of an electric current can be generated from a normal fuel cell. Fuel cells can be many types for example PEMFC, SPEFC and MFPM, SOFC enzymatic biofuel cells, direct carbon fuel cell, phosphoric acid fuel cell and alkaline fuel cell. Let’s describe them one by one. PEMFC stands for proton exchange membrane fuel cell. The design of this cell is so designed to separates the anode and cathode. Before 1970’s PEMFC was termed as SPEFC, that is solid polymer electrolyte fuel cell. When on the anode side the hydrogen diffuses into protons and electrons. The protons present here often react to oxidants and hence we call this fuel cell as MFPM multi facilitated protons membrane. In this chemical reaction the protons often travel too reach cathode, while the electrons are present in the external circuit. The reason of electrons being left to external circuit is that the membrane which carries the protons is insulating in nature. Here it must be noted that movement of electrons carry electric current.
The energy efficiency of fuel cells is dependent upon the amount of fuel which is extracted from the cell. However it is not recommended for the equipments which require more power. The reason is that the more you draw energy from the fuel cells the less efficient they become. As described earlier the typical cell generates 0.7 volts of electricity. However even in this 0.7 voltage only 50 percent hydrogen generates energy. The fuel cells which operate in an open air lose their energy efficiency due the air pressure. Fuel cells are used in remote areas where there is scarcity of electricity. The biggest application of fuel cells is in Spacecrafts, off grid power supply, distributed generation, emergency power systems and military operations. Fuel cells are easy to carry and they are affordable.