Hydrogen synthesis from seawater by means of solar energy

Abstract

In the electrolysis of seawater as a source of hydrogen, two options exist for the performance of the electrolysis process. The first option is the total desalination of the sea water and then add alkalis for the process of electrolysis to produce hydrogen in the cathode and oxygen in the anode. The disadvantages of this approach are the high cost of desalination and the water treatment to make it alkaline. The main advantage is the ability to use developed technology for the direct electrolysis of fresh water. The second option is to design an electrolyze system capable of utilizing sea water for direct electrolysis at a low power density and electrolyze only a small portion of the water in contact with the electrodes. The advantage of this method is the lower capital required for the system and natural elimination of the waste brine which is only slightly enriched with salts. Also using this technic is possible to produce important amounts of chlorine as a sub-product and also magnesium and sodium as hydroxides that have many uses in the chemical industry. In this research we produced hydrogen via electrolysis from simply natural resources, seawater and solar energy. In order to carry out this experiment we used water from Bahia of Kino Sonora, a place no too far from the University of Sonora, only 100 kilometers away, and a 100-W solar panel that generate DC electricity using directly sunlight that is an abundant resource in the coasts of Sonora. In this work we have been able to produce about 2 liters of hydrogen per hour and nearly 1.2 liters of chlorine per hour with a normal direct radiation of 900 W/m2. This technique could be the solution to the fuels problematic of the ethnicities that inhabit the shores of Sonora and other states of México.