2.1 OVERVIEW OF ELECTROLYSIS
According to the Free Online Dictionary, electrolysis can be defined as chemical decomposition which is produced by passing an electric current through a liquid or solution containing ions.
Although everybody has a feeling of what energy is; it is still difficult to give precise definition for it. Energy can be viewed as the ability to cause changes. The first law of thermodynamics is simply an expression of energy principle, and it asserts that energy is a thermodynamic property. The second law of thermodynamics asserts that energy has equality as well as quantity, and actual processes occur in the direction of decreasing quality of energy.
Although the principles of thermodynamics have been in existence since million years ago, thermodynamics did not emerge as a science until the construction of the first successful atmospheric steam engine in England by Thomas Savery in 1697 and Thomas Newcomen in1712. Although these engines were very slow and inefficient, they still opened new way of development to the new science.
There are other two types of thermodynamic laws which are zeroth law of thermodynamics and third law of thermodynamics. Zeroth law explained if two systems are in thermal equilibrium with a third system, they must be in thermal equilibrium with each other. This law helps define the notion of temperature. Whereas the third law discuss regarding to the entropy of a system approaches a constant value as the temperature approaches zero. The entropy of a system at absolute zero is typically zero, and in all cases is determined only by the number of different ground states it has. Specifically, the entropy of a pure crystalline substance at absolute zero temperature is zero.
By providing energy from a battery, water (H2O) can be separated into the diatomic molecules of hydrogen (H2) and oxygen (O2). This process is named as Electrolysis of Water. It is a good example of the application of the four thermodynamic potentials which consist of internal energy, the enthalpy, the Helmholtz free energy and the Gibbs free energy. Diagram 1 below shows an example of electrolysis’s process:
Nicholson and Carlisle has started water observations in 1800. There were some developments related to water electrolysis. For instances, on 1902 around 400 industrial water electrolysis units were conducted, and on 1939 with capability to produce 10000 Nm3/h first large water electrolysis plant was construct, and also on 1966 the General Electric was the primary industrial solid polymer electrolysis system was built. Besides, in 1972 high temperature solid oxide electrolysers were launched, while on 1978 earliest large alkaline electrolysis unit was built. Even though by time pass through the improvement of different water electrolysis systems are obvious, their energy efficiency is still under 60% in working manner. For the energy efficiency define relation between combustion...