Electrolysis is an energy intensive method of producing hydrogen.
However, when the energy used for its generation is derived from renewable
sources such as wind or solar energy, it is deemed a favorable method for the
production of electricity (Turner, 2004). Electrolysis produces relatively pure
hydrogen gas, (Kreuter, 1998), and can be used for large scale and small scale
production, (Grigoriev, 2006).
Electrolysis occurs when an electric current is passed through water
forcing it to electrochemically decompose to its elements, hydrogen and oxygen.
The production of hydrogen and oxygen from the electrolysis of water is the
foundation of “sunlight-driven water-splitting systems” (Xiang et al, 2016).
Electrolysis is an older technology that first appeared in literature in the
eighteen hundreds where Demian and Van Troostwijk used a machine than generates
electrostatic to create electricity which was then discharged on gold
electrodes (Levie, 2005). Future methods to produce hydrogen can involve the
direct current being “supplied by the mechanical energy created by a wind
turbine to power electrolysis or primary
applications (the power grid)” (Haman & Stiever, 2006). The activation
barriers of pure water are overcome during electrolysis as surplus energy is supplied
in the form of overpotential. An electrolysis reaction is described as:
The above reaction equation is made up of two half reactions which
occur at the negative and positively charged electrodes: cathode and anode,
An ion-conducting electrolyte solution separates the aforementioned electrodes
(Ahisong et al, 2012). Haman & Stiever construed that thirty-nine kilowatts
per hour of electricity is required to generate one kilogram of hydrogen gas.
Levene 2005 likens a gallon of gasoline to a kilogram of hydrogen: the “Gallon
Further, Barbir illustrates in literature that electrolysis operates
much so as a polymer electrolyte membrane (PEM) fuel cell, except it is in
reverse. The thermodynamic threshold potential difference necessary to achieve
electrolysis is 1.229 volts (Chaplin, 2012). It is deduced from literature that increasing
the potential difference between the electrodes thus increases the rate of
production of hydrogen once it surpasses the threshold of 1.229 volts. However,
Barbir states that a reduction of efficiency of hydrogen production is
experienced once this voltage surpasses 1.6 volts.
Another interesting method of producing hydrogen by means of natural
sources is enzymatic hydrogen generation” (Zhang et al, 2007). This method
utilizes 13 enzymes to produce hydrogen from starch and water through a
synthetic enzymatic pathway.