Review of energy harvesting techniques in wireless sensor-based pipeline monitoring networks

With the ever-increasing use of Wireless Sensor Networks (WSNs) in scientific and industrial applications, the users' desire to ensure their uninterrupted operation over long periods of time could not be fulfilled by relying solely on batteries with finite energy supply, storage, and lifetime. In pipeline monitoring networks, the finiteness of these resources engenders unavoidable downtimes caused by the replacement of spent batteries, inspection and repairs of resulting failures, including pipe leaks and ruptures. All of this would result in costly operational interruptions, leading to concomitant disruptions in fluid transport logistics, and crippling production losses in the monitored systems. This spurred an ongoing and vigorous research effort into devising a suitable logistics-aware energy management scheme to ensure an uninterrupted and cost-efficient operation. At the core of this scheme, lies energy harvesting which provides monitored networks with vital operation-sustaining energy gathered from natural sources emanating from the sensors’ surroundings. This paper therefore aims at giving a comprehensive review of these alternative energy sources, the mechanisms behind harvesting their energies and various ways of integrating each of them into WSNs. This review is vital in providing engineers with an up-to-date comparative study and a valuable roadmap of, and selection guidelines for, the state-of-the-art energy harvesting technologies used. This study reviews the pros and cons of different harvesting technologies and concludes with some pointers towards some research gaps that need to be addressed to facilitate the development of reliable and cost-effective leak detection schemes, with longer operational lifetimes, better reliability, cost efficiency and logistical support.