A review on the development of IoT enabled hydrogen sensing systems

Abstract

The energy requirements of the world are increasing day by day and this can be mainly attributed to the booming global population and economy coupled with rapid urbanization and industrialization. Around 80 % of the world’s energy requirements are fulfilled by fossil fuels. This over-dependency on fossil fuels has levied an enormous toll on the environment and the human race. Moreover, fossil fuel reserves run out relatively quickly. Hence a renewable, efficient, and cleaner source of energy such as hydrogen is the need of the hour, to help save the environment from further degradation. Hydrogen in its pure form is already being widely used as an energy source in numerous sectors like chemical industries, refineries, transport industry, etc.  

 Hydrogen has low ignition energy (0.02mJ), is highly flammable, and burns with an invisible flame. Hence, hydrogen leaks can be much more catastrophic than other gaseous fuels [2]. Owing to its ultra-small molecular size, high diffusion coefficient, high detonation sensitivity, and large flame propagation velocity, containment, and confinement of hydrogen gas is a very precarious task and the required infrastructure should be designed and prepared carefully. A rapid sensing mechanism to accurately detect, monitor, and quantify the hydrogen leaks on a real-time basis is extremely important in industries and other sectors utilizing hydrogen in enormous quantities to help prevent it from forming potentially explosive mixtures with air and leading to catastrophic situations.

The primitive methods of hydrogen sensing included techniques such as Bubble testing, Catalytic combustion, Mass Spectrometers, Gas Chromatographs, Ultrasonic leak detection, Glow plugs, etc. These techniques were either too slow or required huge infrastructural requirements and thus were unable to be efficiently employed in industries and plants for hydrogen detection. These drawbacks have given rise to the development of a variety of hydrogen sensors such as electrochemical sensors, Pd-film and Pd-alloy films, metal oxide sensors, optical devices, etc. The development of sensors alone solves only a part of the problem. A complete hydrogen sensing system is essential consisting of a signal conditioning unit, analog to digital converter, and a microcontroller coupled with a wireless communication system as shown in figure 1. This is required to establish seamless machine-to-machine communication for both sending alerts to the user and communication of sensor data. Also, a data logging system is required to enable the operators to act swiftly and to provide concrete data for further analysis to help avert leakages in the future.

With the advent of the Internet of Things (IoT) the development of such a sensing system seems more realistic than in the past. This article intends to provide a review of the various components required to help establish an efficient IoT-enabled measuring system for hydrogen sensors. The article also explores the different options available for components such as signal conditioning, analog to digital converters, microcontrollers, wireless communication systems, and data logging and analysis services such as cloud storage to create a smart sensing ecosystem, weighing in on the pros and cons of each of the options. Thus, identifying the best choice of components that can help realize the measurement system which can detect hydrogen on a real-time basis, send alerts, and make the collected data available across the globe for swift action to help prevent catastrophes.