With its allure of free energy and maintenance-free operation for lifetimes of 10 and even 15 years, energy harvesting (EH) is grabbing the attention of potential users in many markets. Recent EH developments have made great progress, and the pieces appear to be falling into place.
System components such as microcontrollers (MCUs), RFICs, and power-supply ICs have had to drastically reduce their power consumption and increase performance to complete a useful energy-harvesting system. In addition, software that controls the power management, data collection, and transmission processes while avoiding any unnecessary power consumption is essential.
A transition from the “introduction” phase to the “growth” phase is occurring for energy harvesting and related micro battery products, according to analysts from the Darnell Group writing in Energy Harvesting & Micro Batteries: Market Forces and Demand Characteristics, Third Edition. The authors of the IDTechEx report “Energy Harvesting in Action” are similarly enthusiastic about numerous successful applications in a variety of markets such as automotive, consumer electronics, buildings and industrial sites, and military and aerospace.
Since the driving force for many energy-harvesting systems is a wireless application that must avoid battery replacement and node maintenance, wireless sensing networks (WSNs) are a common component in all of these markets. Figure 1 shows a typical energy-harvesting wireless sensor node for a WSN.
Anxiously Awaiting Applications
Cars and bridges were among the earliest targets for energy harvesting, but buildings could be the killer app. Initially, tire pressure monitoring systems (TPMS) for cars and light-duty trucks served as the poster children for energy harvesting based on microelectromechanical systems (MEMS). A microsystem version of the node in Figure 1 was supposed to displace the battery-based systems currently in use by generating energy from tire vibration using MEMS-based piezoelectric technology.
More recently, however, market research firms and companies pursuing TPMS have admitted that this EH application is unlikely to occur anytime soon, despite the fact that other countries are now pursuing the federally mandated requirement (FMVSS No. 138) as well.
Next in line for creating the need for monitoring based on energy harvesting were bridges and other structures subject to stress and aging, with inherent vibration as the ambient energy source. The 2007 collapse of the I-35W bridge in Minnesota seemed to present a compelling and reinforcing case for structural monitoring. Existing technology has been used to show several products’ viability to detect and avoid problems in this application. However, significant sales appear to be more of a future, rather than near-term, reality.
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