Hybrid Energy Harvesting Systems

ABSTRACT: Harvesting electrical energy from thermal gradients can be a useful tool for numerous applications from large scale waste heat recovery to small scale self-powered sensors. Increasing the efficiency of traditional bulk thermoelectric generators (TEG) has been the subject of much development for 30-40 years yet efficiency improvements for commercially viable devices have been marginal. The proposed Magneto-thermoelectric generator (MTG) not only has the potential for higher energy densities than today"s TEG"s, but is by nature well suited for use in multi-modal energy harvesting from light, thermal, vibration, and magnetic fields. The concept can be used as a thermal backplane for photovoltaics (PV) in order to increase PV conversion efficiency while generating additional power from the thermal gradient. Additionally, since the MTG thermal harvesting mechanism consists of a mechanical oscillator, both thermal and vibration energy can be harvested with the same structure. Finally, by using a novel Galfenol/PZT laminate for mechanical to electrical conversion, both mechanically and magnetically induced strains will be converted into useful electricity. Prime Photonics LC (PPLC) and Virginia Tech (VT) propose a hybrid multimode energy harvester which achieves high efficiency by maximizing the synergy between photovoltaic, magnetostrictive, piezoelectric, and magneto-thermoelectric conversion technologies. BENEFIT: The benefits of this proposed technology are as follows: High efficiency magneto-electric conversion: The proposed piezoelectric and magneto-electric laminate has a higher power density than a piezoelectric effect alone. Thermal design: Optimization of thermal performance by minimizing contact resistance and maximizing flux results in substantial improvements to power conversion efficiency. Magnetic design: Design of the soft magnetic material thru rare-earth doping will achieve high magnetic susceptibilities and appropriate Curie temperatures. Novel applications: The proposed device high efficiency thermal harvester will not only increase photovoltaic efficiency, but will enable numerous other waste heat and wireless sensor applications. The Prime Photonics LC (PPLC) proposed Hybrid Photovoltaic / Magnetic-Thermoelectric Power Harvester (Hybrid Harvester) will be a highly compact technology capable of efficiently generating power from solar energy using the heat that is generated from photovoltaic cells. During the Phase I project, PPLC will identify candidate Air Force and other Department of Defense (DoD) applications for Hybrid Harvester harvesting technology. Much of PPLC current product development focus targets sensor operation in hot environments (turbines, combustors, generators) where much thermal energy is available. The Hybrid Harvester technology will also find many applications in solar power as well, particularly for microsystems applications. PPLC is developing a family of novel multi-source energy harvesting wireless technologies (Omnivore) that will that will be capable of harvesting energy from flow, vibration and temperature and the Hybrid Harvester will significantly complement this product technology roadmap. PPLCs work in energy harvesting, miniature/low-power radio, and sensor technology enables a convergence of these technologies into new class of self-powered energy harvesting wireless sensor products that will find significant utility in energy, military and industrial applications.