Multimode Energy Harvesting Materials and Structures
Objective: Self-biased magnetoelectric (ME) composites, defined as materials that enable large ME coupling under external AC magnetic field in the absence of DC magnetic field, are an interesting, challenging and practical field of research. Eliminating the need of DC magnetic bias provides great potential towards energy harvesting applications.
For energy harvesting applications, the ME composite could be used to generate the electricity from stray AC magnetic field present in the surrounding (as shown in Figure 1) and additionally from converting the mechanical vibrations into electricity with higher efficiency. The ME energy harvester could be used to harness energy from both vibrations and AC magnetic field at the same time. This combination is expected to enhance the power output and conversion efficiency. Building upon this hypothesis, we plan to demonstrate co-fired self-biased ME composite structure with coupling coefficient larger than 2.5 V/cm.Oe at 1 kHz under 1Oe AC field and high power density ME energy harvester with output power of 25 mW for monitoring the health of electromagnetic motors in the industrial plants.
Team: Dr. Shashank Priya (Materials and ME harvester fabrication), Dong Ha (electrical interface), Muhammad Hajj (Analytical modeling), one graduate student (ME harvester design, fabrication, and testing), and one undergraduate student (platform validation through testing on the motors). Focus in recruiting students will be on underrepresented groups in STEM.
Development of High-power Devices for Fluidic Power Harvesting
Objective: Energy harvesting from air and water flows has been mostly achieved by using turbines. At small scales, these turbines become very inefficient and piezoelectric transduction may be more appropriate. Recently, we were able to show that a flexible beam will undergo large static deformation when placed in a fluid flow.
Under proper conditions, nonlinearities arising from the aerodynamic flow and structure deformation will cause the beam to undergo self-induced limit cycle oscillations; a phenomenon that has not been observed in the past and that can be effectively exploited for energy harvesting. In this work, we will exploit aeroelastic vibrations of flexible elements to optimize the performance of such harvesters in terms of power density over a broad range of flow speeds.
Team: Dr. Muhammad Hajj (nonlinear dynamics) Shashank Priya (Materials), Dong Ha (electrical interface), one graduate student. Focus in recruiting students will be on underrepresented groups in STEM. All the faculty members will serve on the thesis committee of the graduate student.
Mechanical Motion Rectifier (MMR) based Vibration Energy Harvesting
Objective: The research objective is to solve the fundament challenge of large-scale vibration energy harvesting by creating mechanical motion rectifier (MMR) based energy harvesters to meet the need of industry. Specially, we will (1) design a type of motion mechanism MMR to directly convert the oscillatory vibration into unidirectional motion of the generator, in a similar way as electrical voltage rectifier converts the AC into DC, and (2) we will use MMR for the electromagnetic energy harvesting at 10s Watts to 100KW scale, including from railway freight trains, ground vehicles, civil structures, and ocean wave energy harvesting, as shown in image.
The fundamental challenge of vibration energy harvesting, especially at large energy scale, is the vibration itself – a reciprocating oscillation with time varying speed and amplitude. The oscillatory nature of the vibrations creates huge challenging in energy harvesting efficiency, power density, and system reliability. Figure 3 shows different design of the mechanical motion rectifiers for various energy harvesting applications. A key component in these designs is one-way clutch, which allows the motion to be transferred in one direction only, as the ones used in engine starters and bicycle gears. The one-way clutch can be analogous as the semi-conductor diode which allows electric current to transfer in one direction only. Inspired by the electrical voltage rectifier using a center-tapped transformer and two diodes (Figure 3-b), we can synthesize the mechanical motion rectifier. In Figure 3 we used rack pinion, ball screws, chain, or bevel gears to realize to linear to rotational mechanism and the one-directional motion. In longer term, we would like to develop the new motion mechanism by transferring the knowledge in semiconductor based modern electronics into mechanical domain, to create innovative vibration energy harvester.
Team: Dr. Lei Zuo of Mechanical Engineering is leading this project with the support of Prof Khai Ngo of Electrical Engineering. System-level design, modelling, and analysis, and prototyping will be completed, including mechanical energy conversion and energy harvesting electronics and storage. In some applications, like the vehicle suspension and civil structures, self-powered vibration control will be implemented to realize the dual functions of vibration reduction and energy harvesting. Two graduate students in mechanical engineering and electrical engineering will participate in this project.
Thermoelectric Energy Harvesting for Nuclear Power Industry
Objective: The objective of this project is to investigate and deliver a self-powered thermoelectrically driven sensing and actuation system for the urgent need of nuclear industry that can be integrated directly onto key nuclear components, including pipes, pump housing, heat exchangers, reactor vessels, and shielding structures (Fig. 4), as well as secondary-side components like the secondary and steam loops (not shown).
In the event of an off-normal situation the intrinsic heat load present in reactor components can be used to power self-contained sensing/actuation assemblies attached to key system components. Such an approach is intrinsically fault tolerant: in the event that temperatures increase, the amount of available energy will increase, which will make more power available for applications. The system can also be used during normal conditions to provide enhanced monitoring of key system components in an energy sustainable manner. The package will include aheat pipe-assistive thermoelectric generator (TEG), microcontroller, signal processing, and a wireless radio package, and will be environmentally hardened to survive radiation, flooding, vibration, mechanical shock (explosions), corrosion, and excessive temperature. The energy harvested from the intrinsic heat of reactor components can power sensors, provide bi-directional communication, recharge batteries for other safety systems, and actuate valves, pumps, and other devices when all other power sources are unavailable.
Team: Prof Lei Zuo of Mechanical Engineering will lead this project with the support of harvesting material expert Prof Shashank Priya and harvesting electronics expert Prof Dong Ha. System-level design, modeling, prototyping, lab evaluation, and nuclear environment tests will be completed, including thermoelectric energy harvester, microcontoller, harvesting electronics, energy storage, sensor and actuator integration, and radiation protection. Graduate students with mechanical engineering, electrical engineering and heat transfer background will participate in this project. We also expect to provide training one or two high school students in the summer.
The Wireless Sensor Node Powered by Energy Harvesting from Automobiles
Objective: The key objective of this project is to perform a feasibility study and assessment on energy harvesting technology to enable self-powered, wireless sensing of electric vehicle (EV) battery pack systems. Currently, the state (voltage, current, and temperature) of a Li-ion battery pack of an EV is monitored with over 95 hard-wired sensors.
Installation of a large number of cables and growing weight of the wire harness is an emerging issue. Utilization of wireless sensor nodes powered by harvested ambient energy (e.g. thermal, vibration) is a novel solution for battery pack monitoring. Establishing a viable self-powered, wireless sensing system for EV battery packs would enable scalability of operational monitoring, elimination of 1-2 meters of sensor wire harness, and reduce the manufacturing cost.
Team: Professor Dong Ha and one graduate student, with the support of Profs Hajj and Priya.
Quantum dot based thermoelectric cells for a high Z value
Objective: The research objective is to develop high efficiency, low cost TE modules by using QD-based TE materials. The efficiency of the TE material is determined by the dimensionless figure of merit , where , , and are the Seebeck coefficient, electrical conductivity, and thermal conductivity.
The recent Herman/Yin collaboration (Fig. 6) showed that tailored nanostructured materials can lead to new possibilities for next-generation TE materials, in part because the nanostructure can decrease thermal conductivity without decreasing electrical conductivity. This project is to fabricate TE module prototypes and measure its performance.
Team: Irving Herman (Appl. Phys.), Huiming Yin (Solid Mech.), Yuan Yang (Mater. Sci.), and 1 graduate student.
Battery for harvesting low-grade heat
Objective: The objective of this project is to use the electrochemical Seebeck effect to develop a novel battery for harvesting low-grade heat sources (less than 150 °C), which are ubiquitous in nature and human activities, such as geothermal/solar thermal energy, manufacturing, and energy processes. Efficient and low-cost approaches to utilize such thermal energy sources are urgently needed for reducing carbon footprint.
Among various methods to harvest heat, thermoelectrics – based on the voltage across a semiconductor under a temperature gradient known as the Seebeck effect – has been widely studied (see C1), which has a Seebeck coefficient (S) of approximately 0.2 mV/K. In parallel with the Seebeck effect, the electrode potential of an electrochemical reaction also depends on temperature, which is called the electrochemical Seebeck effect. The corresponding temperature coefficient could be as high as 1-3 mV/K, which originates form entropy change in the electrode reaction. The electrochemical Seebeck effect indicates that battery voltage also depends on temperature, as of a battery is the difference between two electrodes. Consequently, a cycle can be constructed by discharging the battery at T1 and charging back at T2 with a lower voltage. In such a cycle, work is produced as the voltage gain (green area), while the energy input is that to heat up cell and entropy change in reaction. Therefore, to maximize efficiency, materials with high and small are needed. We plan to carry out research in following directions to maximize efficiency: develop better materials with high and small through screening electrochemical materials and first-principle calculation, design an efficient heat recuperation system to reduce energy loss on heat capacity. Heat recuperation system could harvest thermal energy rejected in the cooling process and reuse it for heating. Our preliminary calculation shows that 70% is reasonable for large systems, which could reduce total energy loss by greater than 50%. System integration. We plan to demonstrate a lab-scale prototype of both battery units and heat recuperation system.
Team: Yuan Yang (Mater. Sci.), Maria Feng (Sensing), Nanfang Yu (Appl. Phys.), and 1 graduate student.
Dual glass bifacial module packaging with smart coating
Objective: As crystalline silicon PV cells are replaced with high efficiency bifacial cells, a new opportunity is emerging to develop novel solar PV module packaging methods to enhance bifacial solar module efficiency. Although the design of bifacial PV cells has addressed the energy transmission by using an anti-reflective (AR) coating on the front surface and reflective coating at the back surface, the overall energy efficiency of BIPV modules may significantly increase with new module packaging methods.
One way this may be accomplished is by using rear side reflectance of solar modules to harvest infrared light that is not absorbed by today’s thin crystalline silicon solar cells. This can be accomplished by applying a reflective coating on the back glass of the dual-glass module and utilizing a tunable meta-surface, based on phase transition materials (e.g., SmNiO3), on the front glass of the dual-glass module.
To ensure the mechanical stability of the PV modules and provide sufficient protection to the cells and metallization, a dual-glass module packaging method is proposed in Fig. 8. Two thermoplastic polyolefin (TPO) layers with high electrical and hydrolysis resistance, two identical high-mechanical and thermal resistant glasses, and two smart coatings for solar spectrum management are layered up in an approximately symmetric pattern with respect to the bifacial solar cells. This symmetric configuration leads to a zero stress in the bifacial cells under bending caused by the external load forces (wind, snow) during its service life. This improved mechanical stability avoids the need for a metallic frame around the module, thus reducing the cost and furthermore, the risk of potential induced degradation. Two smart coatings, one anti-reflective coating layer with a tunable meta-surface on the front glass and another reflective coating on the back glass are utilized to manage the solar spectrum that the bifacial PV cells receive in order to maximize their energy conversion. To validate the efficiency and environmental sustainability of the new panel, we will compare with the conventional alternative using EVA.
Team: Nanfang Yu (Appl. Phys.), Vasilis Fthenakis (Solar Energy & Life Cycle Analysis), Huiming Yin (Solid Mech.), and 1 Post-doctoral scholar.
An evacuated tube collector for concentrated solar power harvesting
Objective: This project is to design and develop a novel evacuated tube collector (ETC) containing a parabolic trough with a passive sun tracker to concentrate solar irradiation to the heat collector for solar heat harvesting. In the first year, we will identify the materials for each part of the ETC and fabricate a prototype for performance test and application in energy efficient buildings.
Based on the result, a practical design of this novel ETC will be finalized and a demonstration project can be conducted in the second year. Different from the conventional ETC, the novel ETC proposed in this project is illustrated with the cross section in Fig. 9. The ETC has a large diameter of 1 ft. The heat receiver is aligned along the central line of the tube, which shall be oriented in the north-south direction, and a reflective parabolic trough is placed in the lower half of tube with a novel passive tracking system to concentrate the solar irradiation onto the receiver with a concentration ratio of 50. Due to the insulation of heat convection and conduction by vacuum, high temperatures of the work fluid (250~400°C) are expected in yearly round. One key part of this technology is to keep the parabolic trough’s symmetric axis in line with the sun light, which requires a solar tracking system. Inspired by sunflowers, we invented a passive tracking system, which can automatically track the sun’s orientation. The harvested high quality heat can be converted to electricity by TE cells or heat engines. To maximize electricity generation, we will use thermal oil as the working fluid. Based on our laboratory test results, the projected temperature of the working fluid can reach 350oC, at which the existing Rankine cycle generator or future thermoelectric generator can achieve efficiencies of over 15% [24, 25].
A self-powered sensing system for energy efficient buildings
Objective: This project is to develop a self-powered wireless sensing methodology for a glass-fin curtain wall system and demonstrate its working mechanism and performance through a prototype device for building management system (BMS), which is schematically illustrated in Fig. 10. It will include five parts: the energy-harvesting device with an integrated photovoltaic (PV) cell and thermoelectric generator (TEG), power management, sensors, wireless communication device, and management system.
In application, environmental energy will be harvested by PV cells from the irradiation or by TE cell from the high temperature gradient between the outdoor and indoor when irradiation is not accessible. The harvested electricity from the energy-harvesting device will be used to power the wireless sensors and communication device to transfer sensing data to the data server forming a building management system (BMS). Wi-Fi will be used for the wireless communications. The BMS will connect with different sensors such as heating/cooling, ventilating, and air conditioning (HVAC), moisture, and acoustics for automatic control of the indoor environment conditioning. The BMS is also connected with the Internet for remote monitoring and control of the house, thus forms an automatic optimal comfort system for building sectors especially residential low-load homes to achieve optimal IAQ, comfort and energy efficiency. This system will ease the installation, operation and maintenance of the building management system and enable monitoring and control of the indoor air environments and comfort.
Team: Maria Feng (Sensing.), Huiming Yin (Solid Mech.), Sharon Di (Sys. Optimization) and 1 graduate student.
Railway Energy Harvester
Objective: Railway freight vehicle is lack of electricity and thus smart technologies, such as logistics tracking, GPS, and electromagnetic braking systems are hard to implement to the freight rail cars. The objective of this project is to design a vibration energy harvester and storage to enable the smart technologies on freight rail cars.
An electromagnetic energy harvester has been designed and prototyped with capability to handle large force in the rail vibrations. Tests on the Instron hydraulic machine using the recorded rail car vibration data show that the harvester can generate an average 38W power. An energy management circuit, which can storage the energy in a 12 V battery and give 12V, 24V, and 110V DC output is being developed for need of rail industry, such as powering the electrical braking in the freight cars or the GPS to track the vehicle position.
Team: Dr. Lei Zuo of Mechanical Engineering is leading this project with the support of Dr. Ha Dong of Electrical Engineering. A graduate student is working on this project.