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Novel Energy Harvesting Technology for Unattended Sensors

Description:

TECHNOLOGY AREA(S): Electronics, 

OBJECTIVE: The goal of this effort is to determine the feasibility, develop concepts and demonstrate novel technology for harvesting 10-100 mW of power (average) in close proximity to energized conductors or overhead power lines. 

DESCRIPTION: The Army’s modernization priority for Network Command, Control, Communications and Intelligence (NC3I), requires a variety of sensing assets capable of intelligent, autonomous and reliable processing and communications. Unattended sensors have become more capable with technology advances, and can integrate with networks to provide raw, processed or fully analyzed sensor data. The sensors, processing and communications require power which can be provided by batteries, but even sub-Watt sensing assets require large, heavy batteries to operate for extended periods of time. Advancements in technology have driven improved efficiency and cost in energy harvesting, especially with solar-based methods [1]. However, solar is not viable in many cases and is highly dependent on environmental conditions. Energy harvesting for many unattended technologies must be dependable in a variety of environments, especially indoors where sun exposure is unlikely. In addition, RF methods for Internet of Things (IoT) devices that harvest wifi/bluetooth signals are only applicable to a small sub-set of use cases. Such sensing assets are often located in close-proximity to strong 50 or 60 Hz electric and magnetic-fields produced by conductors providing power to loads or overhead power lines. These devices are ideally sustained by power extracted from these fields, enabling extended operation, although energy-harvesting from any ubiquitous source would enable in-situ placement of low-power sensing devices with no need for energy-related maintenance [2][3][4]. Viable energy-harvesting methods for low-frequency fields do not currently exist to provide enough power in a form factor suitable [5][6] for the majority of unattended sensing applications. The development of this technology would greatly expand the number of viable permanent installation points for a future Army network of assets, and ensure minimal maintenance with respect to the powering of the devices. Low-power sensing devices typically consume 10-100 mW, depending on the application, which informs the amount of harvesting needed to operate the sensors indefinitely. Harvesting technology capable of sustaining sensing assets in the majority of emplacement scenarios near powered conductors (e.g., high/low-temp, day/night/indoors) will enable unattended operation and eliminate the logistical difficulties of wiring power or swapping batteries. Phase I: Briefly describe expectations and desired results/end product. (Please spell out any acronyms. Save your work after each narrative.) The Phase I effort will research concepts and determine the technical feasibility of harvesting energy in close proximity to overhead power lines or powered conductors. This effort should identify and define the physics of energy harvesting to be explored and the enabling technologies to capture and store that energy. The research will include studies on the effects of indoor and outdoor environments on the technology, to include extreme temperatures. The theoretical limits of energy extraction for form factors up to a maximum volume of 100 cm3 (no dimension to exceed 15 cm), factoring in all known/expected losses, will be determined. A successful technology design will be capable of producing at least 10 mW consistently in a 100 cm3 volume or less. This effort will produce a conceptual design for a harvesting technology that can be demonstrated in the Phase II effort. 

PHASE I: The Phase I effort will research concepts and determine the technical feasibility of harvesting energy in close proximity to overhead power lines or powered conductors. This effort should identify and define the physics of energy harvesting to be explored and the enabling technologies to capture and store that energy. The research will include studies on the effects of indoor and outdoor environments on the technology, to include extreme temperatures. The theoretical limits of energy extraction for form factors up to a maximum volume of 100 cm3 (no dimension to exceed 15 cm), factoring in all known/expected losses, will be determined. A successful technology design will be capable of producing at least 10 mW consistently in a 100 cm3 volume or less. This effort will produce a conceptual design for a harvesting technology that can be demonstrated in the Phase II effort. 

PHASE II: In the Phase II effort, the harvesting technology preliminary design from the Phase I effort will be finalized, fully designed and demonstrated. The system build will be capable of demonstrating sustained power output of at least 10 mW in a design volume of less than 100 cm3. The technology will be built and demonstrated in laboratory experiments and in a variety of environmental conditions. The demonstration will include testing at a variety of potential locations expected to provide reasonably large field strength, (e.g. near the exterior of 3-phase cables under load, under power distribution lines). Measurements of the power extracted during these test scenarios will be presented to demonstrate the technologies’ viability as a sustaining source of energy for sensor operation. The system design, five functional units, and detailed performance evaluations will be delivered for government evaluation with the Phase II final report. 

PHASE III: Following a successful system development and demonstration in Phase II, Phase III will extend the effort to refine the design. The finalized design will be suitable for the manufacturing of production quantities for both military applications and commercial markets. Commercialization would be of great interest to the electric power industry while also providing a new technology to assist in military efforts concerned with long-life unattended sensors 

REFERENCES: 

1: N. Lewis, "Research opportunities to advance solar energy utilization", Science 22 Jan 2016: Vol. 351, Issue 6271

KEYWORDS: Electric, Magnetic, Field, Battery, Power, Energy, Sensor, Solar, Harvesting 

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