Production of Hydrogen by Electrolysis of Water: Effects of the Electrolyte Type on the Electrolysis Performances

Romdhane Ben Slama

Higher Institute of Applied Sciences and Technology, University of Gabes, Gabes, Tunisia.

DOI: 10.4236/cweee.2013.22006                

Abstract

The production of hydrogen, vector of energy, by electrolysis way and by using photovoltaic solar energy can be optimized by suitable choice of electrolytes. Distilled water, usually used, due to membrane presence may be substituted by wastewaters, which enters more in their treatment. Waste water such as those of the Cleansing National Office, and also of the factories such as those referring with ammonia, the margines, and even urines that make it possible to produce much more hydrogen as distilled or salted water, more especially as they do not even require an additive or membranes: conventional electrolysers with two electrodes. This study seeks to optimize the choice among waste water and this, by electrolysis in laboratory or over the sun according to produced hydrogen flow criteria, electrolysis efficiency and electric power consumption. The additive used is NaCl. The most significant results are on the one hand the significant increase in the produced hydrogen flow by the addition of the additive; on the other hand the advantage of gas liquor and urine compared to the others tested electrolytes.

Keywords

Hydrogen Production; Electrolysis; Electrolyte; Photovoltaic

1. Introduction

Water electrolysis has long been known to produce hydrogen. However, for membrane electrolysers, used water must be pure.

We show here that wastewater electrolysis gives the same performance or even better performance, because they contain bacteria that produce hydrogen.

Among wastewater include those of ONAS (municipal wastewater), the margine, ammonia water of ammonia production plants, but water with vinegar and urine deemed rich in nitrogenous matter (ammonia) according to recent research from the University of Ohio in the United States.

Hydrogen production by water electrolysis can be economically viable by using electrical energy from renewable sources such as photovoltaic solar energy [1-4].

Our previous studies have relied on the use of salt water as electrolyte [5-8]. In this article, we will vary the nature of the electrolyte leaning towards wastewater deemed by their richness in bacteria which are the basis for hydrogen production. Human urine will also be also used in reference to the work of Boot [9,10].

2. Experimental Set-Up

• 2.1. Parameters of Calculation

• Hydrogen production flow rate: Q_v = V/t With: 

• Absorptive power by the electrolyser: Pa = U.I

• Useful power of the electrolyser: Pu = PCI.Q.r With PCI: lower thermal value of hydrogen (119.910⁶ J/Kg)

ρ: density of hydrogen (0.09 Kg/m³)

• Consumed electric power: W = Pa.t (J)

• Useful efficiency: h = PCI. (V/(Pa.t)).r

• Consumed electric power per unit of volume: W/V = Pa.t/V (J/cm³)

A photovoltaic module with its panel, electrolysers and their electrodes made in various materials, are represented by the following photographs (Figure 1).

2.2. Chemical Characteristics of Waste Water Used

Table 1 represents the characteristics of the waste water used, such as the pH, the resistivity and initial salinity,

Conflicts of Interest

The authors declare no conflicts of interest.

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