The application of fuel cell technology for the construction of a hydrogen permeation monitoring apparatus has been demonstrated. Using the testing material as an anode and the oxygen reduction reaction as an electron sink (cathode), it is possible to build such detectors, which have several advantages in comparison with the existing practice. These detectors make it possible to follow the internal corrosion, with a longer sensor life, and without external energy consumption. Preliminary field results are presented. .
Fuel cells were discovered during the last century, and the first practical application came with the U.S. space program, as a principal source of auxiliary energy in the space vehicles. The fuel cell used in that application is an arrangement of two porous electrodes, an electrolyte in between these two electrodes (ionic contact), and an electrical contact between these two electrodes (electronic contact). Porous electrodes were developed to maximize fuel (hydrogen) and air (oxygen) transport. In this way the maximum amount of electricity is produced [1]. The new approach consists in using a fuel cell as a hydrogen detector. In this application, the electrolyte and the oxygen reduction part of the fuel cell (the cathode) is sandwiched against the metal that is hydrogen permeable (the anode). When the hydrogen appears at the anode, it is oxidized and an equivalent amount of oxygen is reduced. As a result, a current is obtained, which is proportional to the flux of hydrogen that permeates through the material.
Since there is a variety of non-corrosive-electrolytes for different temperature ranges, such as: solid polymers, electrolyte gels or sodium bicarbonate [2], even a high temperature hydrogen permeation detector can be produced. There are few methods of detection available for this type of application [3].
Commercial electrochemical methods use corrosive electrolytes, such as sulfuric acid, or they use expensive palladium membranes as an interface between the hydrogen output from the pipe and its detection by oxidation at the other face of that membrane [4]. As stated above, a hydrogen detector based on the fuel cell technology will not use an electrolyte aggressive to the material, nor an expensive palladium membrane. Also, the sensor life of such a detector is, in principle, the service life of the pipe, which introduces a big advantage compared to current electrochemical type detectors, which have a service life approximately of one year. These features make that the new approach has significant advantages compared to the design of existing hydrogen permeation detectors.
