Hydrogen production via sea water electrolysis

With the eventual exhaustion of conventional fuel resources and the aggravation of environmental damage caused by the use of fuel combustion procedures, the use of hydrogen as an energy source and the development of Hydrogen Energetics is increasingly the major focus of many research laboratories working in the energy sector.

Hydrogen can replace any kind of fuel in any production area, and many experts believe that the use of hydrogen as a source of energy should make it possible to meet the energy requirements of future generations. Hydrogen is an ecologically pure fuel with the greatest heat of combustion. A standard specific enthalpy of hydrogen combustion is equal to 120.9.106 J/kg, and the heating value of hydrogen is several times higher than that of any other comparable type of fuel.

Hydrogen exists in practically inexhaustible reserves and as the combustion of hydrogen produces water, the fuel use of hydrogen is, in fact, a process of water recycling.

Among a great number of procedures being developed for hydrogen production, electrolysis has been widely in use over the previous two decades. Most industrial plants engaged in electrochemical hydrogen production use water solutions containing a strong electrolyte In most cases, salt and alkaline solutions based on pure water.

A highly attractive procedure for electrolytic hydrogen production is to produce hydrogen directly from sea-water, the electrical conductivity of which is due to soluble salts. Sea-water accounts for approximately 97%o of the Earth’s water reserves, and so sea-water electrolysis offers significant advantages against other hydrogen producing technologies, as the water used after production can be –consumed and introduces no additional pollution to the environment.

Sea-water electrolysis is basically determined by near-electrode processes, which are intrinsic for the electrolysis of sodium chloride solutions, as sea water has a peculiar chemical composition with a prevalence of NaCl. Thermodynamic and kinetic analysis alongside other preliminary experiments have shown that electrolysis of sea-water is now a perspective method for hydrogen production.
Also, depending on the reaction conditions, it is possible to recover the following target products: hydrogen, oxygen, chlorine, alkali and sodium hypochlorite, drinking water. Sea-water direct electrolysis creates useful by-products, such as alkalis from catholyte and acids from anolyte.

Early theoretical and experimental works have shown that direct sea water electrolysis can be technically performed and is a perspective procedure for commercial production of hydrogen and associate products.