Laser sensors for energy systems and process industries: Perspectives and directions

Sensors are perhaps the most important and integral components of our modern society. With global warming and environmental pollution garnering ever-increasing attention, as well as solutions for sustainabile and smart cities, the optimized performance of current and future energy systems and process industries is paramount. The accurate sensing and quantification of key parameters of such systems are essential for monitoring, controlling, and optimization efforts. In situ laser-based optical sensors are most suitable for achieving the desired characteristics of accuracy, sensitivity, selectivity, portability, speed, safety, and intelligence. In recent decades, significant progress has been made in the development and deployment of laser-based sensing solutions, although new challenges and opportunities continue to emerge rapidly. In this review paper, we focus on laser absorption spectroscopy (LAS)-based sensors owing to their simple architecture, easy implementation, and market penetration. We detail recent advancements made in LAS variants using new laser sources and techniques. A brief discussion on other laser-based sensing techniques, namely, photoacoustic spectroscopy, laser-induced fluorescence, coherent anti-Stokes Raman spectroscopy, and laser-induced breakdown spectroscopy, is provided to compare these strategies with LAS. The applications of laser-based sensors in various energy systemsincluding engines, turbines, power plants, furnaces, and boilers—as well as process industriessuch as petrochemical, semiconductor, natural gas leak detection, and corrosion detectionare presented, illustrating their many benefits and possible uses. A distinguishing aspect of this review paper is that we present the comparison of previous studies in tabular formats, making it easy to appreciate the recent progress in laser-based sensing solutions. Finally, suggestions on future directions and emerging technologies to pursue for the further enhancement, development, and deployment of laser-based sensors are proposed.