Juan Isidro Franco

Zirfon® as Separator Material for Water Electrolysis Under Specific Conditions

Hydrogen production through alkaline water electrolysis requires improvements to use renewable energy more efficiently. In the process of converting electrical to chemical energy, efforts are focused on reducing energy loss. Electrolysers play two important roles in this process: one of them is as a hydrogen producer and the other is as a storage mechanism. A storage mechanism occurs when there is an excess of renewable energy that can be stored in the form of hydrogen (chemical energy), which is the fuel for the following step, turning chemical into electrical energy again. Electrolysers research is focused on: separators and electrodes materials, electrolytic solutions and cell design. The ideal situation for a separator in an electrolyser is to possess low electric resistance. For that purpose, we compared Zirfon®, silicone and the system without separator. This work studied the behaviour of Zirfon® under specific working conditions: room temperature, an electrolytic solution of potassium hydroxide 35 % w/w and five different distances between electrodes. In order to carry out this experiment, we designed and constructed a special electrolytic cell. The experimental results showed that Zirfon® separator increases the system resistance approximately 15 % when compared to the same system without separator, but it reduces resistance when compared to silicone (excellent insulator). Another result proved that the distances between electrodes proposed in this work did not show bubbles resistance because the system performance improved as the distance became shorter.

Funcionamiento y Estabilidad en el Tiempo de un Sistema Energético con Batería PEM a Combustible y sus Componentes Periféricos

En este trabajo se presenta el desarrollo completo de una bateria de tipo membrana de electrolito polimerico (proton exchange membrane fuel cell stack, PEMFCS), y se muestra el funcionamiento de un sistema experimental completo que esta siendo probado en la Base Esperanza que el Ejercito Argentino posee en la Antartida. El conjunto desarrollado permite trabajar con un minimo de componentes perifericos y ser manejado por personal entrenado con capacitacion basica para su operacion y mantenimiento. La resistencia ohmica de la bateria no difiere de la que se obtendria con seis elementos en serie; su pendiente de Tafel es de 80 mV/dec. Las pruebas de estabilidad en el tiempo alcanzaron 2278 horas y la energia entregada en ese tiempo fue de 4.2 kWh.

A Simple and Inexpensive Method for Evaluating the Photovoltaic Potential: Its Validation in Buenos Aires and Antarctica

The use of renewable energies requires a precise and detailed quantification of the resource available. Because of the cost of solar stations or limited availability of skilled human resources, in most emerging countries, this assessment is made only on a few points scattered over large areas. We report here a simple and inexpensive method to evaluate the photovoltaic (PV) potential for a specific geographic region and a given PV capture technology. The system allows for a direct evaluation of the energy actually obtainable by scaling the measurement array of photovoltaic cells. The proposed measurement system can be installed as a stand-alone unit, or as part of a measurement network, connected to a more sophisticated central hub. The measurement station consists of said PV array (or similar PV array), a resistor, and a portable data logger. The system is calibrated with a device composed of a small array of PV cells, a resistor load bank, and two multimeters. Due to its low cost, this system can be replicated as many times as required with minimal investment. This would make it possible to evaluate the available photovoltaic potential of large regions with accurate and detailed data. Measurements carried out in Buenos Aires and in Antarctica confirm the consistency of the method.

Conductometric Titration to Analyze Nafion® 117 Conductivity

Nafion® membrane presents good chemical, thermal and mechanical stability and excellent protonic conductivity when the material is previously well-hydrated. This type of perfluorosulphonic acid membrane is widely used in a great variety of devices, being mainly applied in the field of renewable energy, for fuel cell and electrolyzers of polymeric electrolytes. Focusing on electrolyzers, it is well known that nowadays, they represent the most promising method for the production of hydrogen, being a well-established, robust and easy to use technology. Using Nafion® membrane in alkaline water electrolyzers as a separator, the aim of this study is to analyze its behaviour under alkaline conditions. Samples of Nafion® 117 membranes in their original state and samples submitted to a previous cleaning treatment and specific hydration treatment were used. This hydration treatment assured an amount of molecules of water per sulphonic acid group (λ = 17–20). The ionic exchange rate between the hydrogen ion of the sulphonic group of Nafion® membrane and the sodium and potassium cations present in the alkaline solution were studied. The chemical kinetics of the reaction was determined with the purpose of establishing the time to carry out conductometric titration of the membrane using sodium and potassium hydroxide as titrates. Results show that the exchange rate of the alkaline ions, in the solution, present a first order kinetics reaction, at the concentration of hydroxide ions in that solution.