Recent Developments in Sensor Technologies for Enabling the Hydrogen Economy

Efforts to create a sustainable hydrogen economy are gaining momentum as governments all over the world are investing in hydrogen production, storage, distribution, and delivery technologies to develop a hydrogen infrastructure. This involves transporting hydrogen in gaseous or liquid form or using carrier gases such as methane, ammonia, or mixtures of methane and hydrogen. Hydrogen is a colorless, odorless gas and can easily leak into the atmosphere leading to economic loss and safety concerns. Therefore, deployment of robust low-cost sensors for various scenarios involving hydrogen is of paramount importance. Here, we review some recent developments in hydrogen sensors for applications such as leak detection, safety, process monitoring in production, transport and use scenarios. The status of methane and ammonia sensors is covered due to their important role in hydrogen production and transportation using existing natural gas and ammonia infrastructure. This review further provides an overview of existing commercial hydrogen sensors and also addresses the potential for hydrogen as an interferent gas for currently used sensors. This review can help developers and users make informed decisions about how to drive hydrogen sensor technology forward and to incorporate hydrogen sensors into the various hydrogen deployment projects in the coming decade. Highly sensitive, robust, mass-deployable, and inexpensive hydrogen sensors are essential for the hydrogen economy. Hydrogen, methane, and ammonia are expected to play a crucial role in a hydrogen economy, and hence reliable sensors for detecting all three is an important requisite. Electrochemical and chemiresistive sensors hold significant promise for achieving these requisites due to their ability to utilize a wide variety of materials and significant research progress has been made in this area. The importance of hydrogen fuel quality sensors is highlighted. The role of hydrogen as an interfering gas for indoor air quality sensors is not well understood and the need for hydrogen-tolerant gas sensors is addressed. An assortment of commercially available sensors for hydrogen, methane, and ammonia are provided and their advantages/disadvantages are discussed.